De Re Metallica, Translated from the First Latin Edition of 1556

by Georg Agricola

FOOTNOTES:

[Pg 353][1] The history of the fusion of ores and of metals is the history of individual processes, and such information as we have been able to discover upon the individual methods previous to Agricola we give on the pages where such processes are discussed. In general the records of the beginnings of metallurgy are so nebular that, if one wishes to shirk the task, he can adopt the explanation of William Pryce one hundred and fifty years ago: "It is very probable that the nature and use of Metals were not revealed to Adam in his state of innocence: the toil and labour necessary to procure and use those implements of the iron age could not be known, till they made part of the curse incurred by his fall: 'In the sweat of thy face shalt thou eat bread, till thou return unto the ground; in sorrow shalt thou eat of it all the days of thy life' (Genesis). That they were very early discovered, however, is manifest from the Mosaick account of Tubal Cain, who was the first instructor of every artificer in Brass [sic] and Iron" (Mineralogia Cornubiensis, p. 2).

It is conceivable that gold could be found in large enough pieces to have had general use in pre-historic times, without fusion; but copper, which was also in use, must have been smelted, and therefore we must assume a considerable development of human knowledge on the subject prior to any human record. Such incidental mention as exists after record begins does not, of course, extend to the beginning of any particular branch of the art—in fact, special arts obviously existed long before such mention, and down to the complete survey of the state of the art by Agricola our dates are necessarily "prior to" some first mention in literature, or "prior to" the known period of existing remains of metallurgical operations. The scant Egyptian records, the Scriptures, and the Shoo King give a little insight prior to 1000 B.C. The more extensive Greek literature of about the 5th to the 3rd centuries B.C., together with the remains of Greek mines, furnish another datum point of view, and the Roman and Greek writers at the beginning of the Christian era give a still larger view. After them our next step is to the Monk Theophilus and the Alchemists, from the 12th to the 14th centuries. Finally, the awakening of learning at the end of the 15th and the beginning of the 16th centuries, enables us for the first time to see practically all that was known. The wealth of literature which exists subsequent to this latter time makes history thereafter a matter of some precision, but it is not included in this undertaking. Considering the great part that the metals have played in civilization, it is astonishing what a minute amount of information is available on metallurgy. Either the ancient metallurgists were secretive as to their art, or the ancient authors despised such common things, or, as is equally probable, the very partial preservation of ancient literature, by painful transcription over a score of centuries, served only for those works of more general interest. In any event, if all the direct or indirect material on metallurgy prior to the 15th century were compiled, it would not fill 40 pages such as these.

[Pg 354] It may be of service to give a tabular summary indicating approximately the time when evidence of particular operations appear on the historical horizon:

Gold washed from alluvial	Prior to recorded civilization
Copper reduced from ores by smelting	Prior to recorded civilization
Bitumen mined and used	Prior to recorded civilization
Tin reduced from ores by smelting	Prior to 3500 B.C.
Bronze made	Prior to 3500 B.C.
Iron reduced from ores by smelting	Prior to 3500 B.C.
Soda mined and used	Prior to 3500 B.C.
Gold reduced from ores by concentration	Prior to 2500 B.C.
Silver reduced from ores by smelting	Prior to 2000 B.C.
Lead reduced from ores by smelting	Prior to 2000 B.C. (perhaps prior to 3500 B.C.)
Silver parted from lead by cupellation	Prior to 2000 B.C.
Bellows used in furnaces	Prior to 1500 B.C.
Steel produced	Prior to 1000 B.C.
Base metals separated from ores by water concentration	Prior to 500 B.C.
Gold refined by cupellation	Prior to 500 B.C.
Sulphide ores smelted for lead	Prior to 500 B.C.
Mercury reduced from ores by (?)	Prior to 400 B.C.
White-lead made with vinegar	Prior to 300 B.C.
Touchstone known for determining gold and silver fineness	Prior to 300 B.C.
Quicksilver reduced from ore by distillation	Prior to Christian Era
Silver parted from gold by cementation with salt	Prior to "
Brass made by cementation of copper and calamine	Prior to "
Zinc oxides obtained from furnace fumes by construction of dust chambers	Prior to "
Antimony reduced from ores by smelting (accidental)	Prior to "
Gold recovered by amalgamation	Prior to "
Refining of copper by repeated fusion	Prior to "
Sulphide ores smelted for copper	Prior to "
Vitriol (blue and green) made	Prior to "
Alum made	Prior to "
Copper refined by oxidation and poling	Prior to 1200 A.D.
Gold parted from copper by cupelling with lead	Prior to 1200 A.D.
Gold parted from silver by fusion with sulphur	Prior to 1200 A.D.
Manufacture of nitric acid and aqua regia	Prior to 1400 A.D.
Gold parted from silver by nitric acid	Prior to 1400 A.D.
Gold parted from silver with antimony sulphide	Prior to 1500 A.D.
Gold parted from copper with sulphur	Prior to 1500 A.D.
Silver parted from iron with antimony sulphide	Prior to 1500 A.D.
First text book on assaying	Prior to 1500 A.D.
Silver recovered from ores by amalgamation	Prior to 1500 A.D.
Separation of silver from copper by liquation	Prior to 1540 A.D.
Cobalt and manganese used for pigments	Prior to 1540 A.D.
Roasting copper ores prior to smelting	Prior to 1550 A.D.
Stamp-mill used	Prior to 1550 A.D.
Bismuth reduced from ore	Prior to 1550 A.D.
Zinc reduced from ore (accidental)	Prior to 1550 A.D.

Further, we believe it desirable to sketch at the outset the development of metallurgical appliances as a whole, leaving the details to special footnotes; otherwise a comprehensive view of the development of such devices is difficult to grasp.

We can outline the character of metallurgical appliances at various periods in a few words. It is possible to set up a description of the imaginary beginning of the [Pg 355]"bronze age" prior to recorded civilization, starting with the savage who accidentally built a fire on top of some easily reducible ore, and discovered metal in the ashes, etc.; but as this method has been pursued times out of number to no particular purpose, we will confine ourselves to a summary of such facts as we can assemble. "Founders' hoards" of the bronze age are scattered over Western Europe, and indicate that smelting was done in shallow pits with charcoal. With the Egyptians we find occasional inscriptions showing small furnaces with forced draught, in early cases with a blow-pipe, but later—about 1500 B.C.—with bellows also. The crucible was apparently used by the Egyptians in secondary melting, such remains at Mt. Sinai probably dating before 2000 B.C. With the advent of the Prophets, and the first Greek literature—9th to 7th century B.C.—we find frequent references to bellows. The remains of smelting appliances at Mt. Laurion (500-300 B.C.) do not indicate much advance over the primitive hearth; however, at this locality we do find evidence of the ability to separate minerals by specific gravity, by washing crushed ore over inclined surfaces with a sort of buddle attachment. Stone grinding-mills were used to crush ore from the earliest times of Mt. Laurion down to the Middle Ages. About the beginning of the Christian era the writings of Diodorus, Strabo, Dioscorides, and Pliny indicate considerable advance in appliances. Strabo describes high stacks to carry off lead fumes; Dioscorides explains a furnace with a dust-chamber to catch pompholyx (zinc oxide); Pliny refers to the upper and lower crucibles (a forehearth) and to the pillars and arches of the furnaces. From all of their descriptions we may conclude that the furnaces had then reached some size, and were, of course, equipped with bellows. At this time sulphide copper and lead ores were smelted; but as to fluxes, except lead for silver, and lead and soda for gold, we have practically no mention. Charcoal was the universal fuel for smelting down to the 18th century. Both Dioscorides and Pliny describe a distillation apparatus used to recover quicksilver. A formidable list of mineral products and metal alloys in use, indicate in themselves considerable apparatus, of the details of which we have no indication; in the main these products were lead sulphide, sulphate, and oxide (red-lead and litharge); zinc oxide; iron sulphide, oxide and sulphate; arsenic and antimony sulphides; mercury sulphide, sulphur, bitumen, soda, alum and potash; and of the alloys, bronze, brass, pewter, electrum and steel.

From this period to the period of the awakening of learning our only light is an occasional gleam from Theophilus and the Alchemists. The former gave a more detailed description of metallurgical appliances than had been done before, but there is little vital change apparent from the apparatus of Roman times. The Alchemists gave a great stimulus to industrial chemistry in the discovery of the mineral acids, and described distillation apparatus of approximately modern form.

The next period—the Renaissance—is one in which our descriptions are for the first time satisfactory, and a discussion would be but a review of De Re Metallica.

[2] See [footnote 2, p. 267], on verbs used for roasting.

[Pg 356][3] Agricola has here either forgotten to take into account his three-palm-thick furnace walls, which will make the length of this long wall sixty-one feet, or else he has included this foot and a half in each case in the six-foot distance between the furnaces, so that the actual clear space is only four and a half feet between the furnace with four feet on the ends.

[Pg 358][4] The paucity of terms in Latin for describing structural members, and the consequent repetition of "beam" (trabs), "timber" (tignum), "billet" (tigillum), "pole" (asser), with such modifications as small, large, and transverse, and with long explanatory clauses showing their location, renders the original very difficult to follow. We have, therefore, introduced such terms as "posts," "tie-beams," "sweeps," "levers," "rafters," "sills," "moulding," "braces," "cleats," "supports," etc., as the context demands.

[Pg 361][5] This set of rafters appears to start from the longitudinal beam.

[Pg 362][6] Devices for creating an air current must be of very old invention, for it is impossible to conceive of anything but the crudest melting of a few simple ores without some forced draft. Wilkinson (The Ancient Egyptians, II, p. 316) gives a copy of an illustration of a foot-bellows from a tomb of the time of Thotmes III. (1500 B.C.). The rest of the world therefore, probably obtained them from the Egyptians. They are mentioned frequently in the Bible, the most pointed reference to metallurgical purposes being Jeremiah (VI, 29): "The bellows are burned, the lead is consumed in the fire; the founder melteth in vain; for the wicked are not plucked away." Strabo (VII, 3) states that Ephorus ascribed the invention of bellows to Anacharsis—a Thracian prince of about 600 B.C.

[Pg 366][7] This whole arrangement could be summarized by the word "hinge."

[Pg 371][8] The rim of this wheel is obviously made of segments fixed in two layers; the "disc" meaning the aggregate of segments on either side of the wheel.

[Pg 376][9] It has not been considered necessary to introduce the modern term twyer in these descriptions, as the literal rendering is sufficiently clear.

[10] Ferruminata. These accretions are practically always near the hearth, and would correspond to English "sows," and therefore that term has been adopted. It will be noted that, like most modern metallurgists, Agricola offers no method for treating them. Pliny (XXXIV, 37) describes a "sow," and uses the verb ferruminare (to weld or solder): "Some say that in the furnace there are certain masses of stone which become soldered together, and that the copper fuses around it, the mass not becoming liquid unless it is transferred to another furnace; it thus forms a sort of knot, as it were, of the metal."

[Pg 377][11] What are known in English as "crucible," "furnace well," "forehearth," "dipping-pot," "tapping-pot," "receiving-pot," etc., are in the text all catinus, i.e., crucible. For easier reading, however, we have assigned the names indicated in the context.

[Pg 379][12] Panes ex pyrite conflati. While the term matte would cover most cases where this expression appears, and in many cases would be more expressive to the modern reader, yet there are instances where the expression as it stands indicates its particular origin, and it has been, therefore, considered advisable to adhere to the literal rendering.

[13] Molybdaena. See [note 37, p. 476]. It was the saturated furnace bottoms from cupellation.

[14] The four elements were earth, air, fire, and water.

[Pg 380][15] "Stones which easily melt in the fire." Nowhere in De Re Metallica does the author explain these substances. However in the Interpretatio (p. 465) he gives three genera or orders with their German equivalents, as follows:—"Lapides qui igni liquescunt primi generis,—Schöne flüsse; secundi,—flüsse zum schmeltzen flock quertze; tertii,—quertze oder kiselstein." We confess our inability to make certain of most of the substances comprised in the first and second orders. We consider they were in part fluor-spar, and in any event the third order embraced varieties of quartz, flint, and silicious material generally. As the matter is of importance from a metallurgical point of view, we reproduce at some length Agricola's own statements on the subject from Bermannus and De Natura Fossilium. In the latter (p. 268) he states: "Finally there now remain those stones which I call 'stones which easily melt in the fire,' because when thrown into hot furnaces they flow (fluunt). There are three orders (genera) of these. The first resembles the transparent gems; the second is not similar, and is generally not translucent; it is translucent in some part, and in rare instances altogether translucent. The first is sparingly found in silver and other mines; the second abounds in veins of its own. The third genus is the material from which glass is made, although it can also be made out of the other two. The stones of the first order are not only transparent, but are also resplendent, and have the colours of gems, for some resemble crystal, others emerald, heliotrope, lapis lazuli, amethyst, sapphire, ruby, chrysolithus, morion (cairngorm?), and other gems, but they differ from them in hardness.... To the first genus belongs the lapis alabandicus (modern albandite?), if indeed it was different from the alabandic carbuncle. It can be melted, according to Pliny, in the fire, and fused for the preparation of glass. It is black, but verging upon purple. It comes from Caria, near Alabanda, and from Miletus in the same province. The second order of stones does not show a great variety of colours, and seldom beautiful ones, for it is generally white, whitish, greyish, or yellowish. Because these (stones) very readily melt in the fire, they are added to the ores from which the metals are smelted. The small stones found in veins, veinlets, and the spaces between the veins, of the highest peaks of the Sudetic range (Suditorum montium), belong partly to this genus and partly to the first. They differ in size, being large and small; and in shape, some being round or angular or pointed; in colour they are black or ash-grey, or yellow, or purple, or violet, or iron colour. All of these are lacking in metals. Neither do the little stones contain any metals which are usually found in the streams where gold dust is collected by washing.... In the rivers where are collected the small stones from which tin is smelted, there are three genera of small stones to be found, all somewhat rounded and of very light weight, and devoid of all metals. The largest are black, both on the outside and inside, smooth and brilliant like a mirror; the medium-sized are either bluish black or ash-grey; the smallest are of a yellowish colour, somewhat like a silkworm. But because both the former and the latter stones are devoid of metals, and fly to pieces under the blows of the hammer, we classify them as sand or gravel. Glass is made from the stones of the third order, and particularly from sand. For when this is thrown into the heated furnace it is melted by the fire.... This kind of stone is either found [Pg 381]in its own veins, which are occasionally very wide, or else scattered through the mines. It is less hard than flint, on account of which no fire can be struck from it. It is not transparent, but it is of many colours—that is to say, white, yellowish, ash-grey, brown, black, green, blue, reddish or red. This genus of stones occurs here and there in mountainous regions, on banks of rivers, and in the fields. Those which are black right through to the interior, and not merely on the surface, are more rare; and very frequently one coloured vein is intersected by another of a different colour—for instance, a white one by a red one; the green is often spotted with white, the ash-grey with black, the white with crimson. Fragments of these stones are frequently found on the surface of the earth, and in the running water they become polished by rubbing against stones of their own or of another genus. In this way, likewise, fragments of rocks are not infrequently shaped into spherical forms.... This stone is put to many uses; the streets are paved with it, whatever its colour; the blue variety is added to the ash of pines for making those other ashes which are used by wool-dyers. The white variety is burned, ground, and sifted, and from this they make the sand out of which glass is made. The whiter the sand is, the more useful it is."

Perusal of the following from Bermannus (p. 458) can leave little doubt as to the first or second order being in part fluor-spar. Agricola derived the name fluores from fluo "to flow," and we in turn obtain "fluorite," or "fluorspar," from Agricola. "Bermannus.—These stones are similar to gems, but less hard. Allow me to explain word for word. Our miners call them fluores, not inappropriately to my mind, for by the heat of fire, like ice in the sun, they liquefy and flow away. They are of varied and bright colours. Naevius.—Theophrastus says of them that they are made by a conflux in the earth. These red fluores, to employ the words just used by you, are the ruby silver which you showed us before. Bermannus.—At the first glance it appears so, although it is not infrequently translucent. Naevius.—Then they are rubies? Bermannus.—Not that either. Naevius.—In what way, then, can they be distinguished from rubies? Bermannus.—Chiefly by this sign, that they glitter more feebly when translucent. Those which are not translucent may be distinguished from rubies. Moreover, fluores of all kinds melt when they are subject to the first fire; rubies do not melt in fire. Naevius.—You distinguish well. Bermannus.—You see the other kind, of a paler purple colour? Naevius.—They appear to be an inferior kind of amethyst, such as are found in many places in Bohemia. Bermannus.—Indeed, they are not very dissimilar, therefore the common people who do not know amethysts well, set them in rings for gems, and they are easily sold. The third kind, as you see here, is white. Naevius.—I should have thought it a crystal. Bermannus.—A fourth is a yellow colour, a fifth ash colour, a sixth blackish. Some are violet, some green, others gold-coloured. Anton.—What is the use of fluores? Bermannus.—They are wont to be made use of when metals are smelted, as they cause the material in the fire to be much more fluid, exactly like a kind of stone which we said is made from pyrites (matte); it is, indeed, made not far from here, at Breitenbrunn, which is near Schwarzenberg. Moreover, from fluores they can make colours which artists use."

[Pg 384][16] Stannum. (Interpretatio,—werck, modern werk). This term has been rendered throughout as "silver-lead" or "silver-lead alloy." It was the argentiferous lead suitable for cupellation. Agricola, in using it in this sense, was no doubt following his interpretation of its use by Pliny. Further remarks upon this subject will be found in [note 33, p. 473].

[Pg 386][17] Expirare,—to exhale or blow out.

[Pg 388][18] Rhetos. The ancient Rhaetia comprised not only the greater part of Tyrol, but also parts of Switzerland and Lombardy. The mining section was, however, in Tyrol.

[19] Noricum was a region south of the Danube, embracing not only modern Styria, but also parts of Austria, Salzberg, and Carinthia.

[20] One drachma of gold to a centumpondium would be (if we assume these were Roman weights) 3 ozs. 1 dwt. Troy per short ton. One-half uncia of silver would be 12 ozs. 3 dwts. per short ton.

[Pg 390][21] For discussion of these fluxes see note page [232].

[22] Carni. Probably the people of modern Austrian Carniola, which lies south of Styria and west of Croatia.

[23] Historical Note on Smelting Lead and Silver.—The history of lead and silver smelting is by no means a sequent array of exact facts. With one possible exception, lead does not appear upon the historical horizon until long after silver, and yet their metallurgy is so inextricably mixed that neither can be considered wholly by itself. As silver does not occur native in any such quantities as would have supplied the amounts possessed by the Ancients, we must, therefore, assume its reduction by either (1) intricate chemical processes, (2) amalgamation, (3) reduction with copper, (4) reduction with lead. It is impossible to conceive of the first with the ancient knowledge of chemistry; the second (see [note 12, p. 297]) does not appear to have been known until after Roman times; in any event, quicksilver appears only at about 400 B.C. The third was impossible, as the parting of silver from copper without lead involves metallurgy only possible during the last century. Therefore, one is driven to the conclusion that the fourth case obtained, and that the lead must have been known practically contemporaneously with silver. There is a leaden figure exhibited in the British Museum among the articles recovered from the Temple of Osiris at Abydos, and considered to be of the Archaic period—prior to 3800 B.C. The earliest known Egyptian silver appears to be a necklace of beads, supposed to be of the XII. Dynasty (2400 B.C.), which is described in the 17th Memoir, Egyptian Exploration Fund (London, 1898, p. 22). With this exception of the above-mentioned lead specimen, silver articles antedate positive evidence of lead by nearly a millennium, and if we assume lead as a necessary factor in silver production, we must conclude it was known long prior to any direct (except the above solitary possibility) evidence of lead itself. Further, if we are to conclude its necessary association with silver, we must assume a knowledge of cupellation for the parting of the two metals. Lead is mentioned in 1500 B.C. [Pg 391]among the spoil captured by Thotmes III. Leaden objects have frequently been found in Egyptian tombs as early as Rameses III. (1200 B.C.). The statement is made by Pulsifer (Notes for a History of Lead, New York 1888, p. 146) that Egyptian pottery was glazed with lead. We have been unable to find any confirmation of this. It may be noted, incidentally, that lead is not included in the metals of the "Tribute of Yü" in the Shoo King (The Chinese Classics, 2500 B.C.?), although silver is so included.

After 1200 or 1300 B.C. evidences of the use of lead become frequent. Moses (Numbers XXXI, 22-23) directs the Israelites with regard to their plunder from the Midianites (1300 B.C.): "Only the gold and the silver, the brass [sic], the iron, the tin, and the lead. Everything that may abide the fire, ye shall make it go through the fire, and it shall be clean; nevertheless, it shall be purified with the water of separation, and all that abideth not the fire ye shall make go through the water." Numerous other references occur in the Scriptures (Psalms XII, 6; Proverbs XVII, 3; XXV, 4; etc.), one of the most pointed from a metallurgical point of view being that of Jeremiah (600 B.C.), who says (VI, 29-30): "The bellows are burned, the lead is consumed of the fire; the founder melteth in vain; for the wicked are not plucked away. Reprobate silver shall men call them because the Lord hath rejected them." From the number of his metaphors in metallurgical terms we may well conclude that Jeremiah was of considerable metallurgical experience, which may account for his critical tenor of mind. These Biblical references all point to a knowledge of separating silver and lead. Homer mentions lead (Iliad XXIV, 109), and it has been found in the remains of ancient Troy and Mycenae (H. Schliemann, "Troy and its Remains," London, 1875, and "Mycenae," New York, 1877). Both Herodotus (I, 186) and Diodorus (II, 1) speak of the lead used to fix iron clamps in the stone bridge of Nitocris (600 B.C.) at Babylon.

Our best evidence of ancient lead-silver metallurgy is the result of the studies at Mt. Laurion by Edouard Ardaillon (Mines du Laurion dans l'Antiquité, Paris, 1897). Here the very extensive old workings and the slag heaps testify to the greatest activity. The re-opening of the mines in recent years by a French Company has well demonstrated their technical character, and the frequent mention in Greek History easily determines their date. These deposits of argentiferous galena were extensively worked before 500 B.C. and while the evidence of concentration methods is ample, there is but little remaining of the ancient smelters. Enough, however, remains to demonstrate that the galena was smelted in small furnaces at low heat, with forced draught, and that it was subsequently cupelled. In order to reduce the sulphides the ancient smelters apparently depended upon partial roasting in the furnace at a preliminary period in reduction, or else upon the ferruginous character of the ore, or upon both. See notes p. [27] and p. [265]. Theognis (6th century B.C.) and Hippocrates (5th century B.C.) are frequently referred to as mentioning the refining of gold with lead; an inspection of the passages fails to corroborate the importance which has been laid upon them. Among literary evidences upon lead metallurgy of later date, Theophrastus (300 B.C.) describes the making of white-lead with lead plates and vinegar. Diodorus Siculus (1st century B.C.), in his well-known quotation from Agatharchides (2nd century B.C.) with regard to gold mining and treatment in Egypt, describes the refining of gold with lead. (See [note 8, p. 279].) Strabo (63 B.C.-24 A.D.) says (III, 2, 8): "The furnaces for [Pg 392]silver are constructed lofty in order that the vapour, which is dense and pestilent, may be raised and carried off." And again (III, 2, 10), in quoting from Polybius (204-125 B.C.): "Polybius, speaking of the silver mines of New Carthage, tells us that they are extremely large, distant from the city about 20 stadia, and occupy a circuit of 400 stadia; that there are 40,000 men regularly engaged in them, and that they yield daily to the Roman people (a revenue of) 25,000 drachmae. The rest of the process I pass over, as it is too long; but as for the silver ore collected, he tells us that it is broken up and sifted through sieves over water; that what remains is to be again broken, and the water having been strained off it is to be sifted and broken a third time. The dregs which remain after the fifth time are to be melted, and the lead being poured off, the silver is obtained pure. These silver mines still exist; however, they are no longer the property of the State, neither these nor those elsewhere, but are possessed by private individuals. The gold mines, on the contrary, nearly all belong to the State. Both at Castlon and other places there are singular lead mines worked. They contain a small proportion of silver, but not sufficient to pay for the expense of refining" (Hamilton's Trans.). Dioscorides (1st century A.D.), among his medicines, describes several varieties of litharge, their origin, and the manner of making white-lead (see on pp. [465], [440]), but he gives no very tangible information on lead smelting. Pliny, at the same period in speaking of silver, (XXXIII, 31), says: "After this we speak of silver, the next folly. Silver is only found in shafts, there being no indications like shining particles as in the case of gold. This earth is sometimes red, sometimes of an ashy colour. It is impossible to melt it except with lead ore (vena plumbi), called galena, which is generally found next to silver veins. And this the same agency of fire separates part into lead, which floats on the silver like oil on water." (We have transferred lead and silver in this last sentence, otherwise it means nothing.) Also (XXXIV, 47) he says: "There are two different sources of lead, it being smelted from its own ore, whence it comes without the admixture of any other substance, or else from an ore which contains it in common with silver. The metal, which flows liquid at the first melting in the furnace, is called stannum that at the second melting is silver; that which remains in the furnace is galena, which is added to a third part of the ore. This being again melted, produces lead with a deduction of two-ninths." We have, despite some grammatical objections, rendered this passage quite differently from other translators, none of whom have apparently had any knowledge of metallurgy; and we will not, therefore, take the several pages of space necessary to refute their extraordinary and unnecessary hypotheses. From a metallurgical point of view, two facts must be kept in mind,—first, that galena in this instance was the same substance as molybdaena, and they were both either a variety of litharge or of lead carbonates; second, that the stannum of the Ancients was silver-lead alloy. Therefore, the metallurgy of this paragraph becomes a simple melting of an argentiferous lead ore, its subsequent cupellation, with a return of the litharge to the furnace. Pliny goes into considerable detail as to varieties of litharge, for further notes upon which see p. [466]. The Romans were most active lead-silver miners, not only in Spain, but also in Britain. There are scores of lead pigs of the Roman era in various English museums, many marked "ex argent." Bruce (The Roman Wall, London, 1852, p. 432) describes some Roman lead furnaces in Cumberland where the draught was secured by driving a tapering tunnel into the hills. The Roman lead slag ran high in metal, and formed a basis for quite an industry in England in the early 18th century (Hunt, British Mining, London, 1887, p. 26, etc.). There is nothing in mediæval literature which carries us further with lead metallurgy than the knowledge displayed by Pliny, until we arrive at Agricola's period. The history of cupellation is specially dealt with in note on p. [465].

[Pg 394][25] Cadmia. In the German Translation this is given as kobelt. It would be of uncertain character, but no doubt partially furnace calamine. (See note on p. [112].)

[26] Pompholyx. (Interpretatio gives the German as Weisser hütten rauch als ober dem garherde und ober dem kupfer ofen). This was the impure protoxide of zinc deposited in the furnace outlets, and is modern "tutty." The ancient products, no doubt, contained arsenical oxides as well. It was well known to the Ancients, and used extensively for medicinal purposes, they dividing it into two species—pompholyx and spodos. The first adequate description is by Dioscorides (V, 46): "Pompholyx differs from spodos in species, not in genus. For spodos is blacker, and is often heavier, full of straws and hairs, like the refuse that is swept from the floors of copper smelters. But pompholyx is fatty, unctuous, white and light enough to fly in the air. Of this there are two kinds—the one inclines to sky blue and is unctuous; the other is exceedingly white, and is extremely light. White pompholyx is made every time that the artificer, in the preparation and perfecting of copper (brass?) sprinkles powdered cadmia upon it to make it more perfect, for the soot which rises being very fine becomes pompholyx. Other pompholyx is made, not only in working copper (brass?), but is also made from cadmia by continually blowing with bellows. The manner of doing it is as follows:—The furnace is constructed in a two-storied building, and there is a medium-sized aperture opening to the upper chamber; the building wall nearest the furnace is pierced with a small opening to admit the nozzle of the bellows. The building must have a fair-sized door for the artificer to pass in and out. Another small building must adjoin this, in which are the bellows and the man who works them. Then the charcoal in the furnace is lighted, and the artificer continually throws broken bits of cadmia from the place above the furnace, whilst his assistant, who is below, throws in charcoals, until all of the cadmia inside is consumed. By this means the finest and lightest part of the [Pg 396]stuff flies up with the smoke to the upper chamber, and adheres to the walls of the roof. The substance which is thus formed has at first the appearance of bubbles on water, afterward increasing in size, it looks like skeins of wool. The heaviest parts settle in the bottom, while some fall over and around the furnaces, and some lie on the floor of the building. This latter part is considered inferior, as it contains a lot of earth and becomes full of dirt."

Pliny (XXXIV, 33) appears somewhat confused as to the difference between the two species: "That which is called pompholyx and spodos is found in the copper-smelting furnaces, the difference between them being that pompholyx is separated by washing, while spodos is not washed. Some have called that which is white and very light pompholyx, and it is the soot of copper and cadmia; whereas spodos is darker and heavier. It is scraped from the walls of the furnace, and is mixed with particles of metal, and sometimes with charcoal." (XXXIV, 34.) "The Cyprian spodos is the best. It is formed by fusing cadmia with copper ore. This being the lightest part of the metal, it flies up in the fumes from the furnace, and adheres to the roof, being distinguished from the soot by its whiteness. That which is less white is immature from the furnace, and it is this which some call 'pompholyx.'" Agricola (De Natura Fossilium, p. 350) traverses much the same ground as the authors previously quoted, and especially recommends the pompholyx produced when making brass by melting alternate layers of copper and calamine (cadmia fossilis).

[27] Oleo, ex fece vini sicca confecto. This oil, made from argol, is probably the same substance mentioned a few lines further on as "wine," distilled by heating argol in a retort. Still further on, salt made from argol is mentioned. It must be borne in mind that this argol was crude tartrates from wine vats, and probably contained a good deal of organic matter. Heating argol sufficiently would form potash, but that the distillation product could be anything effective it is difficult to see.

[28] Aqua valens. No doubt mainly nitric acid, the preparation of which is explained at length in [Book X, p. 439].

[Pg 397][29] Quod cum ignis consumit non modo una cum eo, quae ipsius stibii vis est, aliqua auri particula, sed etiam argenti, si cum auro fuerit permistum, consumitur. The meaning is by no means clear. On p. [451] is set out the old method of parting silver from gold with antimony sulphide, of which this may be a variation. The silver combines with sulphur, and the reduced antimony forms an alloy with the gold. The added iron and copper would also combine with the sulphur from the antimony sulphide, and no doubt assist by increasing the amount of free collecting agent and by increasing the volume of the matte. (See [note 17, p. 451].)

[30] There follow eight different methods of treating crude bullion or rich concentrates. In a general way three methods are involved,—1st, reduction with lead or antimony, and cupellation; 2nd, reduction with silver, and separation with nitric acid; 3rd, reduction with lead and silver, followed by cupellation and parting with nitric acid. The use of sulphur or antimony sulphide would tend to part out a certain amount of silver, and thus obtain fairly pure bullion upon cupellation. But the introduction of copper could only result deleteriously, except that it is usually accompanied by sulphur in some form, and would thus probably pass off harmlessly as a matte carrying silver. (See [note 33 below].)

[31] It is not very clear where this lead comes from. Should it be antimony? The German translation gives this as "silver."

[Pg 398][32] These powders are described in Book VII., p. [236]. It is difficult to say which the second really is. There are numbers of such recipes in the Probierbüchlein (see [Appendix B]), with which a portion of these are identical.

[33] A variety of methods are involved in this paragraph: 1st, crude gold ore is smelted direct; 2nd, gold concentrates are smelted in a lead bath with some addition of iron—which would simply matte off—the lead bullion being cupelled; 3rd, roasted and unroasted pyrites and cadmia (probably blende, cobalt, arsenic, etc.) are melted into a matte; this matte is repeatedly roasted, and then re-melted in a lead bath; 4th, if the material "flies out of the furnace" it is briquetted with iron ore and lime, and the briquettes smelted with copper matte. Three products result: (a) slag; (b) matte; (c) copper-gold-silver alloy. The matte is roasted, re-smelted with lead, and no doubt a button obtained, and further matte. The process from this point is not clear. It appears that the copper bullion is melted with lead, and normally this product would be taken to the liquation furnace, but from the text it would appear that the lead-copper bullion was melted again with iron ore and pyrites, in which case some of the copper would be turned into the matte, and the lead alloy would be richer in gold and silver.

[Pg 399] Historical Note on Gold.—There is ample evidence of gold being used for ornamental purposes prior to any human record. The occurrence of large quantities of gold in native form, and the possibility of working it cold, did not necessitate any particular metallurgical ingenuity. The earliest indications of metallurgical work are, of course, among the Egyptians, the method of washing being figured as early as the monuments of the IV Dynasty (prior to 3800 B.C.). There are in the British Museum two stelae of the XII Dynasty (2400 B.C.) (144 Bay 1 and 145 Bay 6) relating to officers who had to do with gold mining in Nubia, and upon one there are references to working what appears to be ore. If this be true, it is the earliest reference to this subject. The Papyrus map (1500 B.C.) of a gold mine, in the Turin Museum (see [note 16, p. 129]), probably refers to a quartz mine. Of literary evidences there is frequent mention of refining gold and passing it through the fire in the Books of Moses, arts no doubt learned from the Egyptians. As to working gold, ore as distinguished from alluvial, we have nothing very tangible, unless it be the stelae above, until the description of Egyptian gold mining by Agatharchides (see [note 8, p. 279]). This geographer, of about the 2nd century B.C., describes very clearly indeed the mining, crushing, and concentration of ore and the refining of the concentrates in crucibles with lead, salt, and barley bran. We may mention in passing that Theognis (6th Century B.C.) is often quoted as mentioning the refining of gold with lead, but we do not believe that the passage in question (1101): "But having been put to the test and being rubbed beside (or against) lead as being refined gold, you will be fair," etc.; or much the same statement again (418) will stand much metallurgical interpretation. In any event, the myriads of metaphorical references to fining and purity of gold in the earliest shreds of literature do not carry us much further than do those of Shakespeare or Milton. Vitruvius and Pliny mention the recovery or refining of gold with mercury (see [note 12, p. 297] on Amalgamation); and it appears to us that gold was parted from silver by cementation with salt prior to the Christian era. We first find mention of parting with sulphur in the 12th century, with nitric acid prior to the 14th century, by antimony sulphide prior to the 15th century, and by cementation with nitre by Agricola. (See historical note on parting gold and silver, p. [458].) The first mention of parting gold from copper occurs in the early 16th century (see [note 24, p. 462]). The first comprehensive description of gold metallurgy in all its branches is in De Re Metallica.

[Pg 400][34] Rudis silver comprised all fairly pure silver ores, such as silver sulphides, chlorides, arsenides, etc. This is more fully discussed in [note 6, p. 108].

[35] Evolent,—volatilize?

[36] Lapidis plumbarii facile liquescentis. The German Translation gives glantz, i.e., Galena, and the Interpretatio also gives glantz for lapis plumbarius. We are, however, uncertain whether this "easily melting" material is galena or some other lead ore.

[37] Molybdaena is usually hearth-lead in De Re Metallica, but the German translation in this instance uses pleyertz, lead ore. From the context it would not appear to mean hearth-lead—saturated bottoms of cupellation furnaces—for such material would not contain appreciable silver. Agricola does confuse what are obviously lead carbonates with his other molybdaena (see [note 37, p. 476]).

[Pg 401][38] The term cadmia is used in this paragraph without the usual definition. Whether it was cadmia fornacis (furnace accretions) or cadmia metallica (cobalt-arsenic-blende mixture) is uncertain. We believe it to be the former.

[39] Ramentum si lotura ex argento rudi. This expression is generally used by the author to indicate concentrates, but it is possible that in this sentence it means the tailings after washing rich silver minerals, because the treatment of the rudis silver has been already discussed above.

[40] Ustum. This might be rendered "burnt." In any event, it seems that the material is sintered.

[Pg 402][41] Aes purum sive proprius ei color insederit, sive chrysocolla vel caeruleo fuerit tinctum, et rude plumbei coloris, aut fusci, aut nigri. There are six copper minerals mentioned in this sentence, and from our study of Agricola's De Natura Fossilium we hazard the following:—Proprius ei color insederit,—"its own colour,"—probably cuprite or "ruby copper." Tinctum chrysocolla—partly the modern mineral of that name and partly malachite. Tinctum caeruleo, partly azurite and partly other blue copper minerals. Rude plumbei coloris,—"lead coloured,"—was certainly chalcocite (copper glance). We are uncertain of fusci aut nigri, but they were probably alteration products. For further discussion see note on p. [109].

[42] Historical Note on Copper Smelting.—The discoverer of the reduction of copper by fusion, and his method, like the discoverer of tin and iron, will never be known, because he lived long before humanity began to make records of its discoveries and doings. Moreover, as different races passed independently and at different times through the so-called "Bronze Age," there may have been several independent discoverers. Upon the metallurgy of pre-historic man we have some evidence in the many "founders' hoards" or "smelters' hoards" of the Bronze Age which have been found, and they indicate a simple shallow pit in the ground into which the ore was placed, underlaid with charcoal. Rude round copper cakes eight to ten inches in diameter resulted from the cooling of the metal in the bottom of the pit. Analyses of such Bronze Age copper by Professor Gowland and others show a small percentage of sulphur, and this is possible only by smelting oxidized ores. Copper objects appear in the pre-historic remains in Egypt, are common throughout the first three dynasties, and bronze articles have been found as early as the IV Dynasty (from 3800 to 4700 B.C., according to the authority adopted). The question of the origin of this bronze, whether from ores containing copper and tin or by alloying the two metals, is one of wide difference of opinion, and we further discuss the question in [note 53, p. 411], under Tin. It is also interesting to note that the crucible is the emblem of copper in the hieroglyphics. The earliest source of Egyptian copper was probably the Sinai Peninsula, where there are reliefs as early as Seneferu (about 3700 B.C.), indicating that he worked the copper mines. Various other evidences exist of active copper mining prior to 2500 B.C. (Petrie, Researches in Sinai, London, 1906, p. 51, etc.). The finding of crucibles here would indicate some form of refining. Our knowledge of Egyptian copper metallurgy is limited to deductions from their products, to a few pictures of crude furnaces and bellows, and to the minor remains on the Sinai Peninsula; none of the pictures were, so far as we are aware, prior to 2300 B.C., but they indicate a considerable advance over the crude hearth, for they depict small furnaces with forced draught—first a blow-pipe, and in the XVIII Dynasty (about 1500 B.C.) the bellows appear. Many copper articles have been found scattered over the Eastern Mediterranean and Asia Minor of pre-Mycenaean Age, some probably as early as 3000 B.C. This metal is mentioned in the "Tribute of Yü" in the Shoo King (2500 B.C.?); but even less is known of early Chinese metallurgy than of the Egyptian. The remains of Mycenaean, Phoenician, Babylonian, and Assyrian civilizations, stretching over the period from 1800 to 500 B.C., have yielded endless copper and bronze objects, the former of considerable purity, and the latter a fairly constant proportion of from 10% to 14% tin. The copper supply of the pre-Roman world seems to have come largely, first from Sinai, and later from Cyprus, and from the latter comes our word copper, by way of the Romans shortening aes cyprium (Cyprian copper) to cuprum. Research in this island shows that it produced copper from 3000 B.C., and largely because of its copper it passed successively under the domination of the Egyptians, Assyrians, Phoenicians, Greeks, Persians, and Romans. The bronze objects found in Cyprus show 2% to 10% of tin, although tin does not, so far as modern research goes, occur on that island. There can be no doubt that the Greeks obtained their metallurgy from the Egyptians, either direct or second-hand—possibly through Mycenae or Phoenicia. Their metallurgical gods and the tradition of Cadmus indicate this much.

By way of literary evidences, the following lines from Homer (Iliad, XVIII.) have interest as being the first preserved description in any language of a metallurgical work. Hephaestus was much interrupted by Thetis, who came to secure a shield for Achilles, and whose general conversation we therefore largely omit. We adopt Pope's translation:—

There the lame architect the goddess found
Obscure in smoke, his forges flaming round,
While bathed in sweat from fire to fire he flew;
[Pg 403]And puffing loud the roaring bellows blew.
* * *
In moulds prepared, the glowing ore (metal?) he pours.
* * *
"Vouchsafe, oh Thetis! at our board to share
The genial rites and hospitable fare;
While I the labours of the forge forego,
And bid the roaring bellows cease to blow."
Then from his anvil the lame artist rose;
Wide with distorted legs oblique he goes,
And stills the bellows, and (in order laid)
Locks in their chests his instruments of trade;
Then with a sponge, the sooty workman dress'd
His brawny arms embrown'd and hairy breast.
* * *
Thus having said, the father of the fires
To the black labours of his forge retires.
Soon as he bade them blow the bellows turn'd
Their iron mouths; and where the furnace burn'd
Resounding breathed: at once the blast expires,
And twenty forges catch at once the fires;
Just as the God directs, now loud, now low,
They raise a tempest, or they gently blow;
In hissing flames huge silver bars are roll'd,
And stubborn brass (copper?) and tin, and solid gold;
Before, deep fixed, the eternal anvils stand.
The ponderous hammer loads his better hand;
His left with tongs turns the vex'd metal round.
And thick, strong strokes, the doubling vaults rebound
Then first he formed the immense and solid shield;

Even if we place the siege of Troy at any of the various dates from 1350 to 1100 B.C., it does not follow that the epic received its final form for many centuries later, probably 900-800 B.C.; and the experience of the race in metallurgy at a much later period than Troy may have been drawn upon to fill in details. It is possible to fill a volume with indirect allusion to metallurgical facts and to the origins of the art, from Greek mythology, from Greek poetry, from the works of the grammarians, and from the Bible. But they are of no more technical value than the metaphors from our own tongue. Greek literature in general is singularly lacking in metallurgical description of technical value, and it is not until Dioscorides (1st Century A.D.) that anything of much importance can be adduced. Aristotle, however, does make an interesting reference to what may be brass (see note on p. [410]), and there can be no doubt that if we had the lost work of Aristotle's successor, Theophrastus (372-288 B.C.), on metals we should be in possession of the first adequate work on metallurgy. As it is, we find the green and blue copper minerals from Cyprus mentioned in his "Stones." And this is the first mention of any particular copper ore. He also mentions (XIX.) pyrites "which melt," but whether it was a copper variety cannot be determined. Theophrastus further describes the making of verdigris (see [note 4, p. 440]). From Dioscorides we get a good deal of light on copper treatment, but as his objective was to describe medicinal preparations, the information is very indirect. He states (V, 100) that "pyrites is a stone from which copper is made." He mentions chalcitis (copper sulphide, see note on, p. [573]); while his misy, sory, melanteria, caeruleum, and chrysocolla were all oxidation copper or iron minerals. (See notes on p. [573].) In giving a method of securing pompholyx (zinc oxide), "the soot flies up when the copper refiners sprinkle powdered cadmia over the molten metal" (see [note 26, p. 394]); he indirectly gives us the first definite indication of making brass, and further gives some details as to the furnaces there employed, which embraced bellows and dust chambers. In describing the making of flowers of copper (see [note 26, p. 538]) he states that in refining copper, when the "molten metal flows through its tube into a receptacle, the workmen [Pg 404]pour cold water on it, the copper spits and throws off the flowers." He gives the first description of vitriol (see [note 11, p. 572]), and describes the pieces as "shaped like dice which stick together in bunches like grapes." Altogether, from Dioscorides we learn for the first time of copper made from sulphide ores, and of the recovery of zinc oxides from furnace fumes; and he gives us the first certain description of making brass, and finally the first notice of blue vitriol.

The next author we have who gives any technical detail of copper work is Pliny (23-79 A.D.), and while his statements carry us a little further than Dioscorides, they are not as complete as the same number of words could have afforded had he ever had practical contact with the subject, and one is driven to the conclusion that he was not himself much of a metallurgist. Pliny indicates that copper ores were obtained from veins by underground mining. He gives the same minerals as Dioscorides, but is a good deal confused over chrysocolla and chalcitis. He gives no description of the shapes of furnaces, but frequently mentions the bellows, and speaks of the cadmia and pompholyx which adhered to the walls and arches of the furnaces. He has nothing to say as to whether fluxes are used or not. As to fuel, he says (XXXIII, 30) that "for smelting copper and iron pine wood is the best." The following (XXXIV, 20) is of the greatest interest on the subject:—"Cyprian copper is known as coronarium and regulare; both are ductile.... In other mines are made that known as regulare and caldarium. These differ, because the caldarium is only melted, and is brittle to the hammer; whereas the regulare is malleable or ductile. All Cyprian copper is this latter kind. But in other mines with care the difference can be eliminated from caldarium, the impurities being carefully purged away by smelting with fire, it is made into regulare. Among the remaining kinds of copper the best is that of Campania, which is most esteemed for vessels and utensils. This kind is made in several ways. At Capua it is melted with wood, not with charcoal, after which it is sprinkled with water and washed through an oak sieve. After it is melted a number of times Spanish plumbum argentum (probably pewter) is added to it in proportion of ten pounds of the lead to one hundred pounds of copper, and thereby it is made pliable and assumes that pleasing colour which in other kinds of copper is effected by oil and the sun. In many parts of the Italian provinces they make a similar kind of metal; but there they add eight pounds of lead, and it is re-melted over charcoal because of the scarcity of wood. Very different is the method carried on in Gaul, particularly where the ore is smelted between red hot stones, for this burns the metal and renders it black and brittle. Moreover, it is re-melted only a single time, whereas the oftener this operation is repeated the better the quality becomes. It is well to remark that all copper fuses best when the weather is intensely cold." The red hot stones in Gaul were probably as much figments of imagination as was the assumption of one commentator that they were a reverberatory furnace. Apart from the above, Pliny says nothing very direct on refining copper. It is obvious that more than one melting was practised, but that anything was known of the nature of oxidation by a blast and reduction by poling is uncertain. We produce the three following statements in connection with some bye-products used for medicinal purposes, which at least indicate operations subsequent to the original melting. As to whether they represent this species of refining or not, we leave it to the metallurgical profession (XXXIV, 24):—"The flowers of copper are used in medicine; they are made by fusing copper and moving it to another furnace, where the rapid blast separates it into a thousand particles, which are called flowers. These scales are also made when the copper cakes are cooled in water (XXXIV, 35). Smega is prepared in the copper works; when the metal is melted and thoroughly smelted charcoal is added to it and gradually kindled; after this, being blown upon by a powerful bellows, it spits out, as it were, copper chaff (XXXIV, 37). There is another product of these works easily distinguished from smega, which the Greeks call diphrygum. This substance has three different origins.... A third way of making it is from the residues which fall to the bottom in copper furnaces. The difference between the different substances (in the furnace) is that the copper itself flows into a receiver; the slag makes its escape from the furnace; the flowers float on the top (of the copper?), and the diphrygum remains behind. Some say that in the furnace there are certain masses of stone which, being smelted, become soldered together, and that the copper fuses around it, the mass not becoming liquid unless it is transferred to another furnace. It thus forms a sort of knot, as it were, in the metal."

[Pg 405] Pliny is a good deal confused over the copper alloys, failing to recognise aurichalcum as the same product as that made by mixing cadmia and molten copper. Further, there is always the difficulty in translation arising from the fact that the Latin aes was indiscriminately copper, brass, and bronze. He does not, except in one instance (XXXIV., 2), directly describe the mixture of cadmia and copper. "Next to Livian (copper) this kind (corduban, from Spain) most readily absorbs cadmia, and becomes almost as excellent as aurichalcum for making sesterces." As to bronze, there is no very definite statement; but the argentatium given in the quotation above from XXXIV, 20, is stated in XXXIV, 48, to be a mixture of tin and lead. The Romans carried on most extensive copper mining in various parts of their empire; these activities extended from Egypt through Cyprus, Central Europe, the Spanish Peninsula, and Britain. The activity of such works is abundantly evidenced in the mines, but very little remains upon the surface to indicate the equipment; thus, while mining methods are clear enough, the metallurgy receives little help from these sources. At Rio Tinto there still remain enormous slag heaps from the Romans, and the Phoenician miners before them. Professor W. A. Carlyle informs us that the ore worked must have been almost exclusively sulphides, as only negligible quantities of carbonates exist in the deposits; they probably mixed basic and siliceous ores. There is some evidence of roasting, and the slags run from .2 to .6%. They must have run down mattes, but as to how they ultimately arrived at metallic copper there is no evidence to show.

The special processes for separating other metals from copper by liquation and matting, or of refining by poling, etc., are none of them clearly indicated in records or remains until we reach the 12th century. Here we find very adequate descriptions of copper smelting and refining by the Monk Theophilus (see [Appendix B]). We reproduce two paragraphs of interest from Hendrie's excellent translation (p. 305 and 313): "Copper is engendered in the earth. When a vein of which is found, it is acquired with the greatest labour by digging and breaking. It is a stone of a green colour and most hard, and naturally mixed with lead. This stone, dug up in abundance, is placed upon a pile and burned after the manner of chalk, nor does it change colour, but yet loses its hardness, so that it can be broken up. Then, being bruised small, it is placed in the furnace; coals and the bellows being applied, it is incessantly forged by day and night. This should be done carefully and with caution; that is, at first coals are placed in, then small pieces of stone are distributed over them, and again coals, and then stone anew, and it is thus arranged until it is sufficient for the size of the furnace. And when the stone has commenced to liquefy, the lead flows out through some small cavities, and the copper remains within. (313) Of the purification of copper. Take an iron dish of the size you wish, and line it inside and out with clay strongly beaten and mixed, and it is carefully dried. Then place it before a forge upon the coals, so that when the bellows act upon it the wind may issue partly within and partly above it, and not below it. And very small coals being placed round it, place copper in it equally, and add over it a heap of coals. When, by blowing a long time, this has become melted, uncover it and cast immediately fine ashes of coals over it, and stir it with a thin and dry piece of wood as if mixing it, and you will directly see the burnt lead adhere to these ashes like a glue. Which being cast out again superpose coals, and blowing for a long time, as at first, again uncover it, and then do as you did before. You do this until at length, by cooking it, you can withdraw the lead entirely. Then pour it over the mould which you have prepared for this, and you will thus prove if it be pure. Hold it with pincers, glowing as it is, before it has become cold, and strike it with a large hammer strongly over the anvil, and if it be broken or split you must liquefy it anew as before."

The next writer of importance was Biringuccio, who was contemporaneous with Agricola, but whose book precedes De Re Metallica by 15 years. That author (III, 2) is the first to describe particularly the furnace used in Saxony and the roasting prior to smelting, and the first to mention fluxes in detail. He, however, describes nothing of matte smelting; in copper refining he gives the whole process of poling, but omits the pole. It is not until we reach De Re Metallica that we find adequate descriptions of the copper minerals, roasting, matte smelting, liquation, and refining, with a wealth of detail which eliminates the necessity for a large amount of conjecture regarding technical methods of the time.

[43] Cadmia metallica fossilis (see note on p. [112]). This was undoubtedly the complex cobalt-arsenic-zinc minerals found in Saxony. In the German translation, however, this is given as Kalmey, calamine, which is unlikely from the association with pyrites.

[44] The Roman modius (modulus?) held about 550 cubic inches, the English peck holding 535 cubic inches. Then, perhaps, his seven moduli would be roughly, 1 bushel 3 pecks, and 18 vessels full would be about 31 bushels—say, roughly, 5,400 lbs. of ore.

[Pg 406][45] Exhausted liquation cakes (panes aerei fathiscentes). This is the copper sponge resulting from the first liquation of lead, and still contains a considerable amount of lead. The liquation process is discussed in great detail in [Book XI].

[Pg 407][46] The method of this paragraph involves two main objectives—first, the gradual enrichment of matte to blister copper; and, second, the creation of large cakes of copper-lead-silver alloy of suitable size and ratio of metals for liquation. This latter process is described in detail in [Book XI]. The following groupings show the circuit of the various products, the "lbs." being Roman librae:—

Charge.			Products.
1st	Crude ore	5,400 lbs.	Primary matte (1)	600 lbs.
	Lead slags	3 cartloads	Silver-copper alloy (A)	50 "
	Schist	1 cartload	Slags (B)
	Flux	20 lbs.
	Concentrates from slags & accretions	Small quantity
2nd	Primary matte (1)	1,800 lbs.	Secondary matte (2)	1,800 lbs.
	Hearth-lead & litharge	1,200 "	Silver-copper-lead alloy (liquation cakes) (A2)	1,200 "
	Lead ore	300 "	Slags (B2)
	Rich hard cakes (A4)	500 "
	Liquated cakes	200 "
	Slags (B)
	Concentrates from accretions
3rd	Secondary matte (2)	1,800 lbs.	Tertiary matte (3)	1,300 lbs.
	Hearth-lead & litharge	1,200 "	Silver-copper-lead alloy (liquation cakes) (A3)	1,100 "
	Lead ore	300 "	Slags (B3)
	Rich hard cakes (A4)	500 "
	Slags (B2)
	Concentrates from accretions
4th	Tertiary matte (3)	11 cartloads	Quaternary hard cakes matte (4)	2,000 lbs.
	Poor hard cakes (A5)	3 "	Rich hard cakes of matte (A4)	1,500 "
	Slags (B3)
	Concentrates from accretions
5th	Roasted quartz		Poor hard cakes of matte (A5)	1,500 lbs.
	Matte (4) (three times roasted)	11 cartloads	Final cakes of matte (5)
6th	Final matte three times roasted is smelted to blister copper.

The following would be a rough approximation of the value of the various products:—

(1.)	Primary matte	=	158	ounces troy per short ton.
(2.)	Secondary matte	=	85	" " "
(3.)	Tertiary matte	=	60	" " "
(4.)	Quaternary matte	=	Indeterminate.
A.	Copper-silver alloy	=	388	ounces Troy per short ton.
A2	Copper-silver-lead alloy	=	145	" " "
A3	" " "	=	109	" " "
A4	Rich hard cakes	=	97	" " "
A5	Poor hard cakes	=	Indeterminate.
	Final blister copper	=	12	ozs. Troy per short ton.

[Pg 408][47] This expression is usually used for hearth-lead, but in this case the author is apparently confining himself to lead ore, and apparently refers to lead carbonates. The German Translation gives pleyschweiss. The pyrites mentioned in this paragraph may mean galena, as pyrites was to Agricola a sort of genera.

[48] (Excoquitur) ... "si verò pyrites, primò è fornace, ut Goselariae videre licet, in catinum defluit liquor quidam candidus, argento inimicus et nocivus; id enim comburit: quo circa recrementis, quae supernatant, detractis effunditur: vel induratus conto uncinato extrahitur: eundem liquorem parietes fornacis exudant." In the Glossary the following statement appears: "Liquor candidus primo è fornace defluens cum Goselariae excoquitur pyrites,—kobelt; quem parietes fornacis exudant,—conterfei." In this latter statement Agricola apparently recognised that there were two different substances, i.e., that the substance found in the furnace walls—conterfei—was not the same substance as that which first flowed from the furnace—kobelt. We are at no difficulty in recognizing conterfei as metallic zinc; it was long known by that term, and this accidental occurrence is repeatedly mentioned by other authors after Agricola. The substance which first flowed into the forehearth presents greater difficulties; it certainly was not zinc. In De Natura Fossilium (p. 347), Agricola says that at Goslar the lead has a certain white slag floating upon it, the "colour derived from the pyrites (pyriten argenteum) from which it was produced." Pyriten argenteum was either marcasite or mispickel, neither of which offers much suggestion; nor are we able to hazard an explanation of value.

Historical Note on Zinc. The history of zinc metallurgy falls into two distinct [Pg 409]lines—first, that of the metal, and second, that of zinc ore, for the latter was known and used to make brass by cementation with copper and to yield oxides by sublimation for medicinal purposes, nearly 2,000 years before the metal became generally known and used in Europe.

There is some reason to believe that metallic zinc was known to the Ancients, for bracelets made of it, found in the ruins of Cameros (prior to 500 B.C.), may have been of that age (Raoul Jagnaux, Traité de Chimie Générale, 1887, II, 385); and further, a passage in Strabo (63 B.C.-24 A.D.) is of much interest. He states: (XIII, 1, 56) "There is found at Andeira a stone which when burnt becomes iron. It is then put into a furnace, together with some kind of earth, when it distils a mock silver (pseudargyrum), or with the addition of copper it becomes the compound called orichalcum. There is found a mock silver near Tismolu also." (Hamilton's Trans., II, p. 381). About the Christian era the terms orichalcum or aurichalcum undoubtedly refer to brass, but whether these terms as used by earlier Greek writers do not refer to bronze only, is a matter of considerable doubt. Beyond these slight references we are without information until the 16th Century. If the metal was known to the Ancients it must have been locally, for by its greater adaptability to brass-making it would probably have supplanted the crude melting of copper with zinc minerals.

It appears that the metal may have been known in the Far East prior to such knowledge in Europe; metallic zinc was imported in considerable quantities from the East as early as the 16th and 17th centuries under such terms as tuteneque, tuttanego, calaëm, and spiauter—the latter, of course, being the progenitor of our term spelter. The localities of Eastern production have never been adequately investigated. W. Hommel (Engineering and Mining Journal, June 15, 1912) gives a very satisfactory review of the Eastern literature upon the subject, and considers that the origin of manufacture was in India, although the most of the 16th and 17th Century product came from China. The earliest certain description seems to be some recipes for manufacture quoted by Praphulla Chandra Ray (A History of Hindu Chemistry, London, 1902, p. 39) dating from the 11th to the 14th Centuries. There does not appear to be any satisfactory description of the Chinese method until that of Sir George Staunton (Journal Asiatique Paris, 1835, p. 141.) We may add that spelter was produced in India by crude distillation of calamine in clay pots in the early part of the 19th Century (Brooke, Jour. Asiatic Soc. of Bengal, vol. XIX, 1850, p. 212), and the remains of such smelting in Rajputana are supposed to be very ancient.

The discovery of zinc in Europe seems to have been quite independent of the East, but precisely where and when is clouded with much uncertainty. The marchasita aurea of Albertus Magnus has been called upon to serve as metallic zinc, but such belief requires a hypothesis based upon a great deal of assumption. Further, the statement is frequently made that zinc is mentioned in Basil Valentine's Triumphant Chariot of Antimony (the only one of the works attributed to this author which may date prior to the 17th Century), but we have been unable to find any such reference. The first certain mention of metallic zinc is generally accredited to Paracelsus (1493-1541), who states (Liber Mineralium II.): "Moreover there is another metal generally unknown called zinken. It is of peculiar nature and origin; many other metals adulterate it. It can be melted, for it is generated from three fluid principles; it is not malleable. Its colour is different from other metals and does not resemble others in its growth. Its ultimate matter (ultima materia) is not to me yet fully known. It admits of no mixture and does not permit of the fabricationes of other metals. It stands alone entirely to itself." We do not believe that this book was published until after Agricola's works. Agricola introduced the following statements into his revised edition of Bermannus (p. 431), published in 1558: "It (a variety of pyrites) is almost the colour of galena, but of entirely different components. From it there is made gold and silver, and a great quantity is dug in Reichenstein, which is in Silesia, as was recently reported to me. Much more is found at Raurici, which they call zincum, which species differs from pyrites, for the latter contains more silver than gold, the former only gold or hardly any silver." In De Natura Fossilium (p. 368): "For this cadmia is put, in the same way as quicksilver, in a suitable vessel so that the heat of the fire will cause it to sublime, and from it is made a black or brown or grey body which the Alchemists call cadmia sublimata. This possesses corrosive properties to the highest degree. Cognate with this cadmia and pyrites is a compound which the Noricans and Rhetians call zincum." We leave it to readers to decide how near this comes to metallic zinc; in any event, he apparently did not [Pg 410]recognise his conterfei from the furnaces as the same substance as the zincum from Silesia. The first correlation of these substances was apparently by Lohneys, in 1617, who says (Vom Bergwerk, p. 83-4): "When the people in the smelting works are smelting, there is made under the furnace and in the cracks in the walls among the badly plastered stones, a metal which is called zinc or counterfeht, and when the wall is scraped it falls into a vessel placed to receive it. This metal greatly resembles tin, but it is harder and less malleable.... The Alchemists have a great desire for this zinc or bismuth." That this metal originated from blende or calamine was not recognised until long after, and Libavis (Alchymia, Frankfort, 1606), in describing specimens which came from the East, did not so identify it, this office being performed by Glauber, who says (De Prosperitate Germanias, Amsterdam, 1656): "Zink is a volatile mineral or half-ripe metal when it is extracted from its ore. It is more brilliant than tin and not so fusible or malleable ... it turns (copper) into brass, as does lapis calaminaris, for indeed this stone is nothing but infusible zinc, and this zinc might be called a fusible lapis calaminaris, inasmuch as both of them partake of the same nature.... It sublimates itself up into the cracks of the furnace, whereupon the smelters frequently break it out." The systematic distillation of zinc from calamine was not discovered in Europe until the 18th Century. Henkel is generally accredited with the first statement to that effect. In a contribution published as an Appendix to his other works, of which we have had access only to a French translation (Pyritologie, Paris, 1760, p. 494), he concludes that zinc is a half-metal of which the best ore is calamine, but believes it is always associated with lead, and mentions that an Englishman lately arrived from Bristol had seen it being obtained from calamine in his own country. He further mentions that it can be obtained by heating calamine and lead ore mixed with coal in a thick earthen vessel. The Bristol works were apparently those of John Champion, established about 1740. The art of distillation was probably learned in the East.

Definite information as to the zinc minerals goes back to but a little before the Christian Era, unless we accept nebular references to aurichalcum by the poets, or what is possibly zinc ore in the "earth" mentioned by Aristotle (De Mirabilibus, 62): "Men say that the copper of the Mossynoeci is very brilliant and white, no tin being mixed with it; but there is a kind of earth there which is melted with it." This might quite well be an arsenical mineral. But whether we can accept the poets or Aristotle or the remark of Strabo given above, as sufficient evidence or not, there is no difficulty with the description of cadmia and pompholyx and spodos of Dioscorides (1st Century), parts of which we reproduce in [note 26, p. 394]. His cadmia is described as rising from the copper furnaces and clinging to the iron bars, but he continues: "Cadmia is also prepared by burning the stone called pyrites, which is found near Mt. Soloi in Cyprus.... Some say that cadmia may also be found in stone quarries, but they are deceived by stones having a resemblance to cadmia." Pompholyx and spodos are evidently furnace calamine. From reading the quotation given on p. [394], there can be no doubt that these materials, natural or artificial, were used to make brass, for he states (V, 46): "White pompholyx is made every time that the artificer in the working and perfecting of the copper sprinkles powdered cadmia upon it to make it more perfect, the soot arising from this ... is pompholyx." Pliny is confused between the mineral cadmia and furnace calamine, and none of his statements are very direct on the subject of brass making. His most pointed statement is (XXXIV, 2): "... Next to Livian (copper) this kind best absorbs cadmia, and is almost as good as aurichalcum for making sesterces and double asses." As stated above, there can be little doubt that the aurichalcum of the Christian Era was brass, and further, we do know of brass sesterces of this period. Other Roman writers of this and later periods refer to earth used with copper for making brass. Apart from these evidences, however, there is the evidence of analyses of coins and objects, the earliest of which appears to be a large brass of the Cassia family of 20 B.C., analyzed by Phillips, who found 17.3% zinc (Records of Mining and Metallurgy, London, 1857, p. 13). Numerous analyses of coins and other objects dating during the following century corroborate the general use of brass. Professor Gowland (Presidential Address, Inst. of Metals, 1912) rightly considers the Romans were the first to make brass, and at about the above period, for there appears to be no certainty of any earlier production. The first adequate technical description of brass making is in about 1200 A.D. being that of Theophilus, who describes (Hendrie's Trans., p. 307) calcining calamina and mixing it with finely divided copper in glowing crucibles. The process was repeated by adding more calamine and copper until the pots were full of molten metal. This method is repeatedly described with minor variations by Biringuccio, Agricola (De Nat. Fos.), and others, down to the 18th Century. For discussion of the zinc minerals see note on p. [112].

[49] "... non raro, ut nonnulli pyritae sunt, candida...." This is apparently the unknown substance mentioned above.

[Pg 411][50] One drachma is about 3 ounces Troy per short ton. Three unciae are about 72 ounces 6 dwts. Troy per short ton.

[51] In this section, which treats of the metallurgy of plumbum candidum, "tin," the word candidum is very often omitted in the Latin, leaving only plumbum, which is confusing at times with lead. The black tin-stone, lapilli nigri has been treated in a similar manner, lapilli (small stones) constantly occurring alone in the Latin. This has been rendered as "tin-stone" throughout, and the material prior to extraction of the lapilli nigri has been rendered "tin-stuff," after the Cornish.

[52] "... ex saxis vilibus, quae natura de diversa materia composuit." The Glossary gives grindstein. Granite (?).

[53] Historical Notes on Tin Metallurgy. The first appearance of tin lies in the ancient bronzes. And while much is written upon the "Bronze Age" by archæologists, we seriously doubt whether or not a large part of so-called bronze is not copper. In any event, this period varied with each race, and for instance, in Britain may have been much later than Egyptian historic times. The bronze articles of the IV Dynasty (from 3800 to 4700 B.C. depending on the authority) place us on certain ground of antiquity. Professor Gowland (Presidential Address, Inst. of Metals, London, 1912) maintains that the early bronzes were the result of direct smelting of stanniferous copper ores, and while this may be partially true for Western Europe, the distribution and nature of the copper deposits do not warrant this assumption for the earlier scenes of human activity—Asia Minor, Egypt, and India. Further, the lumps of rough tin and also of copper found by Borlase (Tin Mining in Spain, Past and Present, London, 1897, p. 25) in Cornwall, mixed with bronze celts under conditions certainly indicating the Bronze Age, is in itself of considerable evidence of independent melting. To our mind the vast majority of ancient bronzes must have been made from copper and tin mined and smelted independently. As to the source of supply of ancient tin, we are on clear ground only with the advent of the Phœnicians, 1500-1000 B.C., who, as is well known, distributed to the ancient world a supply from Spain and Britain. What the source may have been prior to this time has been subject to much discussion, and while some [Pg 412]slender threads indicate the East, we believe that a more local supply to Egypt, etc., is not impossible. The discovery of large tin fields in Central Africa and the native-made tin ornaments in circulation among the negroes, made possible the entrance of the metal into Egypt along the trade routes. Further, we see no reason why alluvial tin may not have existed within easy reach and have become exhausted. How quickly such a source of metal supply can be forgotten and no evidence remain, is indicated by the seldom remembered alluvial gold supply from Ireland. However, be these conjectures as they may, the East has long been the scene of tin production and of transportation activity. Among the slender evidences that point in this direction is that the Sanskrit term for tin is kastira, a term also employed by the Chaldeans, and represented in Arabic by kasdir, and it may have been the progenitor of the Greek cassiteros. There can be no doubt that the Phœnicians also traded with Malacca, etc., but beyond these threads there is little to prove the pre-western source. The strained argument of Beckmann (Hist. of Inventions, vol. II., p. 207) that the cassiteros of Homer and the bedil of the Hebrews was possibly not tin, and that tin was unknown at this time, falls to the ground in the face of the vast amount of tin which must have been in circulation to account for the bronze used over a period 2,000 years prior to those peoples. Tin is early mentioned in the Scriptures (Numbers XXXI, 22), being enumerated among the spoil of the Midianites (1200 B.C.?), also Ezekiel (600 B.C., XXVII, 12) speaks of tin from Tarshish (the Phœnician settlement on the coast of Spain). According to Homer tin played considerable part in Vulcan's metallurgical stores. Even approximately at what period the Phœnicians began their distribution from Spain and Britain cannot be determined. They apparently established their settlements at Gades (Cadiz) in Tarshish, beyond Gibraltar, about 1100 B.C. The remains of tin mining in the Spanish peninsula prior to the Christian Era indicate most extensive production by the Phœnicians, but there is little evidence as to either mining or smelting methods. Generally as to the technical methods of mining and smelting tin, we are practically without any satisfactory statement down to Agricola. However, such scraps of information as are available are those in Homer (see note on p. [402]), Diodorus, and Pliny.

Diodorus says (V, 2) regarding tin in Spain: "They dig it up, and melt it down in the same way as they do gold and silver;" and again, speaking of the tin in Britain, he says: "These people make tin, which they dig up with a great deal of care and labour; being rocky, the metal is mixed with earth, out of which they melt the metal, and then refine it." Pliny (XXXIV, 47), in the well-known and much-disputed passage: "Next to be considered are the characteristics of lead, which is of two kinds, black and white. The most valuable is the white; the Greeks called it cassiteros, and there is a fabulous story of its being searched for and carried from the islands of Atlantis in barks covered with hides. Certainly it is obtained in Lusitania and Gallaecia on the surface of the earth from black-coloured sand. It is discovered by its great weight, and it is mixed with small pebbles in [Pg 413]the dried beds of torrents. The miners wash these sands, and that which settles they heat in the furnace. It is also found in gold mines, which are called alutiae. A stream of water passing through detaches small black pebbles variegated with white spots, the weight of which is the same as gold. Hence it is that they remain in the baskets of the gold collectors with the gold; afterward, they are separated in a camillum and when melted become white lead."

There is practically no reference to the methods of Cornish tin-working over the whole period of 2,000 years that mining operations were carried on there prior to the Norman occupation. From then until Agricola's time, a period of some four centuries, there are occasional references in Stannary Court proceedings, Charters, and such-like official documents which give little metallurgical insight. From a letter of William de Wrotham, Lord Warden of the Stannaries, in 1198, setting out the regulations for the impost on tin, it is evident that the black tin was smelted once at the mines and that a second smelting or refining was carried out in specified towns under the observation of the Crown Officials. In many other official documents there are repeated references to the right to dig turfs and cut wood for smelting the tin. Under [note 8, p. 282], we give some further information on tin concentration, and the relation of Cornish and German tin miners. Biringuccio (1540) gives very little information on tin metallurgy, and we are brought to De Re Metallica for the first clear exposition.

As to the description on these pages it must be remembered that the tin-stone has been already roasted, thus removing some volatile impurities and oxidizing others, as described on page [348]. The furnaces and the methods of working the tin, here described, are almost identical with those in use in Saxony to-day. In general, since Agricola's time tin has not seen the mechanical and metallurgical development of the other metals. The comparatively small quantities to be dealt with; the necessity of maintaining a strong reducing atmosphere, and consequently a mild cold blast; and the comparatively low temperature demanded, gave little impetus to other than crude appliances until very modern times.

[Pg 419][54] Aureo nummo. German Translation gives reinschen gülden, which was the equivalent of about $1.66, or 6.9 shillings. The purchasing power of money was, however, several times as great as at present.

[Pg 420][55] In the following descriptions of iron-smelting, we have three processes described; the first being the direct reduction of malleable iron from ore, the second the transition stage then in progress from the direct to indirect method by way of cast-iron; and the third a method of making steel by cementation. The first method is that of primitive iron-workers of all times and all races, and requires little comment. A pasty mass was produced, which was subsequently hammered to make it exude the slag, the hammered mass being the ancient "bloom." The second process is of considerable interest, for it marks one of the earliest descriptions of working iron in "a furnace similar to a blast furnace, but much wider and higher." This original German Stückofen or high bloomery furnace was used for making "masses" of wrought-iron under essentially the same conditions as its progenitor the forge—only upon a larger scale. With high temperatures, however, such a furnace would, if desired, yield molten metal, and thus the step to cast-iron as a preliminary to wrought-iron became very easy and natural, in fact Agricola mentions above that if the iron is left to settle in the furnace it becomes hard. The making of malleable iron by subsequent treatment of the cast-iron—the indirect method—originated in about Agricola's time, and marks the beginning of one of those subtle economic currents destined to have the widest bearing upon civilization. It is to us uncertain whether he really understood the double treatment or not. In the above paragraph he says from ore "once or twice smelted they make iron," etc., and in De Natura Fossilium (p. 339) some reference is made to pouring melted iron, all of which would appear to be cast-iron. He does not, however, describe the 16th Century method of converting cast into wrought iron by way of in effect roasting the pig iron to eliminate carbon by oxidation, with subsequent melting into a "ball" or "mass." It must be borne in mind that puddling for this purpose did not come into use until the end of the 18th Century. A great deal of discussion has arisen as to where and at what time cast-iron was made systematically, but without satisfactory answer; in any event, it seems to have been in about the end of the 14th Century, as cast cannon began to appear about that time. It is our impression that the whole of this discussion on iron in De Re Metallica is an abstract from Biringuccio, who wrote 15 years earlier, as it is in so nearly identical terms. Those interested will find a translation of Biringuccio's statement with regard to steel in Percy's Metallurgy of Iron and Steel, London, 1864, p. 807.

Historical Note on Iron Smelting. The archæologists' division of the history of racial development into the Stone, Bronze, and Iron Ages, based upon objects found in tumuli, burial places, etc., would on the face of it indicate the prior discovery of copper metallurgy over iron, and it is generally so maintained by those scientists. The metallurgists have not hesitated to protest that while this distinction of "Ages" may serve the archæologists, and no doubt represents the sequence in which the metal objects are found, yet it by no means follows that this was the order of their discovery or use, but that iron by its rapidity of oxidation has simply not been preserved. The arguments which may be advanced from our side are in the main these. Iron ore is of more frequent occurrence than copper ores, and the necessary reduction of copper oxides (as most surface ores must have been) to fluid metal requires a temperature very much higher than does the reduction of iron oxides to wrought-iron blooms, which do not necessitate fusion. The comparatively greater simplicity of iron metallurgy under primitive conditions is well exemplified by the hill tribes of Northern Nigeria, where in village forges the negroes reduce iron [Pg 421]sufficient for their needs, from hematite. Copper alone would not be a very serviceable metal to primitive man, and he early made the advance to bronze; this latter metal requires three metallurgical operations, and presents immeasurably greater difficulties than iron. It is, as Professor Gowland has demonstrated (Presidential Address, Inst. of Metals, London, 1912) quite possible to make bronze from melting stanniferous copper ores, yet such combined occurrence at the surface is rare, and, so far as known, the copper sources from which Asia Minor and Egypt obtained their supply do not contain tin. It seems to us, therefore, that in most cases the separate fusions of different ores and their subsequent re-melting were required to make bronze. The arguments advanced by the archæologists bear mostly upon the fact that, had iron been known, its superiority would have caused the primitive races to adopt it, and we should not find such an abundance of bronze tools. As to this, it may be said that bronze weapons and tools are plentiful enough in Egyptian, Mycenæan, and early Greek remains, long after iron was demonstrably well known. There has been a good deal pronounced by etymologists on the history of iron and copper, for instance, by Max Müller, (Lectures on the Science of Language, Vol. II, p. 255, London, 1864), and many others, but the amazing lack of metallurgical knowledge nullifies practically all their conclusions. The oldest Egyptian texts extant, dating 3500 B.C., refer to iron, and there is in the British Museum a piece of iron found in the Pyramid of Kephron (3700 B.C.) under conditions indicating its co-incident origin. There is exhibited also a fragment of oxidized iron lately found by Professor Petrie and placed as of the VI Dynasty (B.C. 3200). Despite this evidence of an early knowledge of iron, there is almost a total absence of Egyptian iron objects for a long period subsequent to that time, which in a measure confirms the view of its disappearance rather than that of ignorance of it. Many writers have assumed that the Ancients must have had some superior art of hardening copper or bronze, because the cutting of the gigantic stonework of the time could not have been done with that alloy as we know it; no such hardening appears among the bronze tools found, and it seems to us that the argument is stronger that the oldest Egyptian stoneworkers employed mostly iron tools, and that these have oxidized out of existence. The reasons for preferring copper alloys to iron for decorative objects were equally strong in ancient times as in the present day, and accounts sufficiently for these articles, and, therefore, iron would be devoted to more humble objects less likely to be preserved. Further, the Egyptians at a later date had some prejudices against iron for sacred purposes, and the media of preservation of most metal objects were not open to iron. We know practically nothing of very early Egyptian metallurgy, but in the time of Thotmes III. (1500 B.C.) bellows were used upon the forge.

Of literary evidences the earliest is in the Shoo King among the Tribute of Yü (2500 B.C.?). Iron is frequently mentioned in the Bible, but it is doubtful if any of the early references apply to steel. There is scarcely a Greek or Latin author who does not mention iron in some connection, and of the earliest, none are so suggestive from a metallurgical point of view as Homer, by whom "laboured" mass (wrought-iron?) is often referred to. As, for instance, in the Odyssey (I., 234) Pallas in the guise of Mentes, says according to Pope:

"Freighted with iron from my native land
I steer my voyage to the Brutian strand,
To gain by commerce for the laboured mass
A just proportion of refulgent brass."

[Pg 423] (Brass is modern poetic licence for copper or bronze). Also, in the Odyssey (IX, 465) when Homer describes how Ulysses plunged the stake into Cyclop's eye, we have the first positive evidence of steel, although hard iron mentioned in the Tribute of Yü, above referred to, is sometimes given as steel:

"And as when armourers temper in the ford
The keen-edg'd pole-axe, or the shining sword,
The red-hot metal hisses in the lake."

No doubt early wrought-iron was made in the same manner as Agricola describes. We are, however, not so clear as to the methods of making steel. Under primitive methods of making wrought-iron it is quite possible to carburize the iron sufficiently to make steel direct from ore. The primitive method of India and Japan was to enclose lumps of wrought-iron in sealed crucibles with charcoal and sawdust, and heat them over a long period. Neither Pliny nor any of the other authors of the period previous to the Christian Era give us much help on steel metallurgy, although certain obscure expressions of Aristotle have been called upon (for instance, St. John V. Day, Prehistoric Use of Iron and Steel, London, 1877, p. 134) to prove its manufacture by immersing wrought-iron in molten cast-iron.

[56] Quae vel aerosa est, vel cocta. It is by no means certain that cocta, "cooked" is rightly translated, for the author has not hitherto used this expression for heated. This may be residues from roasting and leaching pyrites for vitriol, etc.

[Pg 428][57] Agricola draws no sharp line of distinction between antimony the metal, and its sulphide. He uses the Roman term stibi or stibium (Interpretatio,—Spiesglas) throughout this book, and evidently in most cases means the sulphide, but in others, particularly in parting gold and silver, metallic antimony would be reduced out. We have been in much doubt as to the term to introduce into the text, as the English "stibnite" carries too much precision of meaning. Originally the "antimony" of trade was the sulphide. Later, with the application of that term to the metal, the sulphide was termed "grey antimony," and we have either used stibium for lack of better alternative, or adopted "grey antimony." The method described by Agricola for treating antimony sulphide is still used in the Harz, in Bohemia, and elsewhere. The stibnite is liquated out at a low heat and drips from the upper to the lower pot. The resulting purified antimony sulphide is the modern commercial "crude antimony" or "grey antimony."

Historical Note on the Metallurgy of Antimony. The Egyptologists have adopted the term "antimony" for certain cosmetics found in Egyptian tombs from a very early period. We have, however, failed to find any reliable analyses which warrant this assumption, and we believe that it is based on the knowledge that antimony was used as a base for eye ointments in Greek and Roman times, and not upon proper chemical investigation. It may be that the ideograph which is interpreted as antimony may really mean that substance, but we only protest that the chemist should have been called in long since. In St. Jerome's translation of the Bible, the cosmetic used by Jezebel (II. Kings IX, 30) and by the lady mentioned by Ezekiel (XXIII, 40), "who didst wash thyself and paintedst thine eyes" is specifically given as stibio. Our modern translation carries no hint of the composition of the cosmetic, and whether some of the Greek or Hebrew MSS. do furnish a basis for such translation we cannot say. The Hebrew term for this mineral was kohl, which subsequently passed into "alcool" and "alkohol" in other languages, and appears in the Spanish Bible in the above passage in Ezekiel as alcoholaste. The term antimonium seems to have been first used in Latin editions of Geber published in the latter part of the 15th Century. In any event, the metal is clearly mentioned by Dioscorides (1st Century), who calls it stimmi, and Pliny, who termed it stibium, and they leave no doubt that it was used as a cosmetic for painting the eyebrows and dilating the eyes. Dioscorides (V, 59) says: "The best stimmi is very brilliant and radiant. When broken it divides into layers with no part earthy or dirty; it is brittle. Some call it stimmi, others platyophthalmon (wide eyed); others larbason, others gynaekeion (feminine).... It is roasted in a ball of dough with charcoal until it becomes a cinder.... It is also roasted by putting it on live charcoal and blowing it. If it is roasted too much it becomes lead." Pliny states (XXXIII, 33 and 34): "In the same mines in which silver is found, properly speaking there is a stone froth. It is white and shining, not transparent; is called stimmi, or stibi, or alabastrum, and larbasis. There are two kinds of it, the male and the female. The most approved is the female, the male being more uneven, rougher, less heavy, not so radiant, and more gritty. The female kind is bright and friable, laminar and not globular. It is astringent and refrigerative, and its principal use is for the eyes.... It is burned in manure in a furnace, is quenched with milk, ground with rain water in a mortar, and while thus turbid it is poured into a copper vessel and purified with nitrum ... above all in roasting it care [Pg 429]should be taken that it does not turn to lead." There can be little doubt from Dioscorides' statement of its turning to lead that he had seen the metal antimony, although he thought it a species of lead. Of further interest in connection with the ancient knowledge of the metal is the Chaldean vase made of antimony described by Berthelot (Comptes Rendus, 1887, CIV, 265). It is possible that Agricola knew the metal, although he gives no details as to de-sulphurizing it or for recovering the metal itself. In De Natura Fossilium (p. 181) he makes a statement which would indicate the metal, "Stibium when melted in the crucible and refined has as much right to be regarded as a metal as is accorded to lead by most writers. If when smelted a certain portion be added to tin, a printer's alloy is made from which type is cast that is used by those who print books." Basil Valentine, in his "Triumphal Chariot of Antimony," gives a great deal that is new with regard to this metal, even if we can accredit the work with no earlier origin than its publication—about 1600; it seems [Pg 430]possible however, that it was written late in the 15th Century (see [Appendix B]). He describes the preparation of the metal from the crude ore, both by roasting and reduction from the oxide with argol and saltpetre, and also by fusing with metallic iron. While the first description of these methods is usually attributed to Valentine, it may be pointed out that in the Probierbüchlein (1500) as well as in Agricola the separation of silver from iron by antimony sulphide implies the same reaction, and the separation of silver and gold with antimony sulphide, often attributed to Valentine, is repeatedly set out in the Probierbüchlein and in De Re Metallica. Biringuccio (1540) has nothing of importance to say as to the treatment of antimonial ores, but mentions it as an alloy for bell-metal, which would imply the metal.

[Pg 432][58] Historical Note on the Metallurgy of Quicksilver. The earliest mention of quicksilver appears to have been by Aristotle (Meteorologica IV, 8, 11), who speaks of it as fluid silver (argyros chytos). Theophrastus (105) states: "Such is the production of quicksilver, which has its uses. This is obtained from cinnabar rubbed with vinegar in a brass mortar with a brass pestle." (Hill's Trans., p. 139). Theophrastus also (103) mentions cinnabar from Spain and elsewhere. Dioscorides (V, 70) appears to be the first to describe the recovery of quicksilver by distillation: "Quicksilver (hydrargyros, i.e., liquid silver) is made from ammion, which is called cinnabari. An iron bowl containing cinnabari is put into an earthen vessel and covered over with a cup-shaped lid smeared with clay. Then it is set on a fire of coals and the soot which sticks to the cover when wiped off and cooled is quicksilver. Quicksilver is also found in drops falling from the walls of the silver mines. Some say there are quicksilver mines. It can be kept only in vessels of glass, lead, tin (?), or silver, for if put in vessels of any other substances it consumes them and flows [Pg 433]through." Pliny (XXXIII, 41): "There has been discovered a way of extracting hydrargyros from the inferior minium as a substitute for quicksilver, as mentioned. There are two methods: either by pounding minium and vinegar in a brass mortar with a brass pestle, or else by putting minium into a flat earthen dish covered with a lid, well luted with potter's clay. This is set in an iron pan and a fire is then lighted under the pan, and continually blown by a bellows. The perspiration collects on the lid and is wiped off and is like silver in colour and as liquid as water." Pliny is somewhat confused over the minium—or the text is corrupt, for this should be the genuine minium of Roman times. The methods of condensation on the leaves of branches placed in a chamber, of condensing in ashes placed over the mouth of the lower pot, and of distilling in a retort, are referred to by Biringuccio (A.D. 1540), but with no detail.

[59] Most of these methods depend upon simple liquation of native bismuth. The sulphides, oxides, etc., could not be obtained without fusing in a furnace with appropriate de-sulphurizing or reducing agents, to which Agricola dimly refers. In Bermannus (p. 439), he says: "Bermannus.—I will show you another kind of mineral which is numbered amongst metals, but appears to me to have been unknown to the Ancients; we call it bisemutum. Naevius.—Then in your opinion there are more kinds of metals than the seven commonly believed? Bermannus.—More, I consider; for this which just now I said we called bisemutum, cannot correctly be called plumbum candidum (tin) nor nigrum (lead), but is different from both, and is a third one. Plumbum candidum is whiter and plumbum nigrum is darker, as you see. Naevius.—We see that this is of the colour of galena. Ancon.—How then can bisemutum, as you call it, be distinguished from galena? Bermannus.—Easily; when you take it in your hands it stains them with black unless it is quite hard. The hard kind is not friable like galena, but can be cut. It is blacker than the kind of crude silver which we say is almost the colour of lead, and thus is different from both. Indeed, it not rarely contains some silver. It generally shows that there is silver beneath the place where it is found, and because of this our miners are accustomed to call it the 'roof of silver.' They are wont to roast this mineral, and from the better part they make metal; from the poorer part they make a pigment of a kind not to be despised." This pigment was cobalt blue (see note on p. [112]), indicating a considerable confusion of these minerals. This quotation is the first description of bismuth, and the above text the first description of bismuth treatment. There is, however, bare mention of the mineral earlier, in the following single line from the Probierbüchlein (p. 1): "Jupiter (controls) the ores of tin and wismundt." And it is noted in the Nützliche Bergbüchlein in association with silver (see [Appendix B]).

[Pg 435][60] This cadmia is given in the German translation as kobelt. It is probably the cobalt-arsenic-bismuth minerals common in Saxony. A large portion of the world's supply of bismuth to-day comes from the cobalt treatment works near Schneeberg. For further discussion of cadmia see note on p. [112].

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BOOK X.

uestions as to the methods of smelting ores and of obtaining metals I discussed in Book IX. Following this, I should explain in what manner the precious metals are parted from the base metals, or on the other hand the base metals from the precious[1]. Frequently two metals, occasionally more than two, are melted out of one ore, because in nature generally there is some amount of gold in silver and in copper, and some silver in gold, copper, lead, and iron; likewise some copper in gold, silver, lead, and iron, and some lead in silver; and lastly, some iron in copper[2]. But I will begin with gold.

Gold is parted from silver, or likewise the latter from the former, whether it be mixed by nature or by art, by means of aqua valens[3], and by powders which consist of almost the same things as this aqua. In order to preserve the sequence, I will first speak of the ingredients of which this aqua is made, then of the method of making it, then of the manner in which gold is parted from silver or silver from gold. Almost all these ingredients contain vitriol or alum, which, by themselves, but much more when joined with saltpetre, are powerful to part silver from gold. As to the other things that are added to them, they cannot individually by their own strength and nature separate those metals, but joined they are very powerful. Since there are many combinations, I will set out a few. In the first, the use of which is common and general, there is one libra of vitriol and as much salt, added to a third of a libra of spring water. The second contains two librae of vitriol, one of saltpetre, and as much spring or river water by weight as will pass away whilst the vitriol is being reduced to powder by the fire. The third consists of four librae of vitriol, two and a half librae of saltpetre, half a libra of alum, and one and a half librae of spring water. The fourth consists of two librae of vitriol, as many librae of saltpetre, one quarter of a libra of alum, and three-quarters of a libra of spring water. The fifth is composed of one libra of saltpetre, three librae of alum, half a libra of brick dust, and three-quarters of a libra of spring water. The sixth consists of four librae of vitriol, three librae of saltpetre, one of alum, one libra likewise of stones which when thrown into a fierce furnace are easily liquefied by fire of the third order, and one and a half librae of spring water. The seventh is made of two librae of vitriol, one and a half librae of saltpetre, half a libra of alum, and one libra of stones which when thrown into a glowing furnace are easily liquefied by fire of the third order, and five-sixths of a libra of spring water. The eighth is made of two librae of vitriol, the same number of librae of saltpetre, one and a half librae of alum, one libra of the lees of the aqua which parts gold from silver; and to each separate libra a sixth of urine is poured over it. The ninth contains two librae of powder of baked bricks, one libra of vitriol, likewise one libra of saltpetre, a handful of salt, and three-quarters of a libra of spring water. Only the tenth lacks vitriol and alum, but it contains three librae of saltpetre, two librae of stones which when thrown into a hot furnace are easily liquefied by fire of the third order, half a libra each of verdigris[4], of stibium, of iron scales and filings, and of asbestos[5], and one and one-sixth librae of spring water.

All the vitriol from which the aqua is usually made is first reduced to powder in the following way. It is thrown into an earthen crucible lined on the inside with litharge, and heated until it melts; then it is stirred with a copper wire, and after it has cooled it is pounded to powder. In the same manner saltpetre melted by the fire is pounded to powder when it has cooled. Some indeed place alum upon an iron plate, roast it, and make it into powder.

Although all these aquae cleanse gold concentrates or dust from impurities, yet there are certain compositions which possess singular power. The first of these consists of one libra of verdigris and three-quarters of a libra of vitriol. For each libra there is poured over it one-sixth of a libra of spring or river water, as to which, since this pertains to all these compounds, it is sufficient to have mentioned once for all. The second composition is made from one libra of each of the following, artificial orpiment, vitriol, lime, alum, ash which the dyers of wool use, one quarter of a libra of verdigris, and one and a half unciae of stibium. The third consists of three librae of vitriol, one of saltpetre, half a libra of asbestos, and half a libra of baked bricks. The fourth consists of one libra of saltpetre, one libra of alum, and half a libra of sal-ammoniac.[6]

All this preparation having been accomplished in order, and the ingredients placed in the ampulla, they are gradually heated over burning charcoal until they begin to exhale vapour and the ampulla is seen to trickle with moisture. But when this, on account of the rising of the vapour, turns red, and the aqua distils through the spout of the operculum, then one must work with the utmost care, lest the drops should fall at a quicker rate than one for every five movements of the clock or the striking of its bell, and not slower than one for every ten; for if it falls faster the glasses will be broken, and if it drops more slowly the work begun cannot be completed within the definite time, that is within the space of twenty-four hours. To prevent the first accident, part of the coals are extracted by means of an iron implement similar to pincers; and in order to prevent the second happening, small dry pieces of oak are placed upon the coals, and the substances in the ampulla are heated with a sharper fire, and the air-holes on the furnace are re-opened if need arise. As soon as the drops are being distilled, the glass ampulla which receives them is covered with a piece of linen moistened with water, in order that the powerful vapour which arises may be repelled. When the ingredients have been heated and the ampulla in which they were placed is whitened with moisture, it is heated by a fiercer fire until all the drops have been distilled[8]. After the furnace has cooled, the aqua is filtered and poured into a small glass ampulla, and into the same is put half a drachma of silver[9], which when dissolved makes the turbid aqua clear. This is poured into the ampulla containing all the rest of the aqua, and as soon as the lees have sunk to the bottom the aqua is poured off, removed, and reserved for use.

Gold is parted from silver by the following method[10]. The alloy, with lead added to it, is first heated in a cupel until all the lead is exhaled, and eight ounces of the alloy contain only five drachmae of copper or at most six, for if there is more copper in it, the silver separated from the gold soon unites with it again. Such molten silver containing gold is formed into granules, being stirred by means of a rod split at the lower end, or else is poured into an iron mould, and when cooled is made into thin leaves. As the process of making granules from argentiferous gold demands greater care and diligence than making them from any other metals, I will now explain the method briefly. The alloy is first placed in a crucible, which is then covered with a lid and placed in another earthen crucible containing a few ashes. Then they are placed in the furnace, and after they are surrounded by charcoal, the fire is blown by the blast of a bellows, and lest the charcoal fall away it is surrounded by stones or bricks. Soon afterward charcoal is thrown over the upper crucible and covered with live coals; these again are covered with charcoal, so that the crucible is surrounded and covered on all sides with it. It is necessary to heat the crucibles with charcoal for the space of half an hour or a little longer, and to provide that there is no deficiency of charcoal, lest the alloy become chilled; after this the air is blown in through the nozzle of the bellows, that the gold may begin to melt. Soon afterward it is turned round, and a test is quickly taken to see whether it be melted, and if it is melted, fluxes are thrown into it; it is advisable to cover up the crucible again closely that the contents may not be exhaled. The contents are heated together for as long as it would take to walk fifteen paces, and then the crucible is seized with tongs and the gold is emptied into an oblong vessel containing very cold water, by pouring it slowly from a height so that the granules will not be too big; in proportion as they are lighter, more fine and more irregular, the better they are, therefore the water is frequently stirred with a rod split into four parts from the lower end to the middle.

The leaves are cut into small pieces, and they or the silver granules are put into a glass ampulla, and the aqua is poured over them to a height of a digit above the silver. The ampulla is covered with a bladder or with waxed linen, lest the contents exhale. Then it is heated until the silver is dissolved, the indication of which is the bubbling of the aqua. The gold remains in the bottom, of a blackish colour, and the silver mixed with the aqua floats above. Some pour the latter into a copper bowl and pour into it cold water, which immediately congeals the silver; this they take out and dry, having poured off the aqua[11]. They heat the dried silver in an earthenware crucible until it melts, and when it is melted they pour it into an iron mould.

The gold which remains in the ampulla they wash with warm water, filter, dry, and heat in a crucible with a little chrysocolla which is called borax, and when it is melted they likewise pour it into an iron mould.

Some workers, into an ampulla which contains gold and silver and the aqua which separates them, pour two or three times as much of this aqua valens warmed, and into the same ampulla or into a dish into which all is poured, throw fine leaves of black lead and copper; by this means the gold adheres to the lead and the silver to the copper, and separately the lead from the gold, and separately the copper from the silver, are parted in a cupel. But no method is approved by us which loses the aqua used to part gold from silver, for it might be used again[12].

The aqua that was first distilled, which contains the silver, is poured into an ampulla wide at the base, the top of which is also smeared with lute and covered by an operculum, and is then boiled as before in order that it may be separated from the silver. If there be so much aqua that (when boiled) it rises into the operculum, there is put into the ampulla one lozenge or two; these are made of soap, cut into small pieces and mixed together with powdered argol, and then heated in a pot over a gentle fire; or else the contents are stirred with a hazel twig split at the bottom, and in both cases the aqua effervesces, and soon after again settles. When the powerful vapour appears, the aqua gives off a kind of oil, and the operculum becomes red. But, lest the vapours should escape from the ampulla and the operculum in that part where their mouths communicate, they are entirely sealed all round. The aqua is boiled continually over a fiercer fire, and enough charcoal must be put into the furnace so that the live coals touch the vessel. The ampulla is taken out as soon as all the aqua has been distilled, and the silver, which is dried by the heat of the fire, alone remains in it; the silver is shaken out and put in an earthenware crucible, and heated until it melts. The molten glass is extracted with an iron rod curved at the lower end, and the silver is made into cakes. The glass extracted from the crucible is ground to powder, and to this are added litharge, argol, glass-galls, and saltpetre, and they are melted in an earthen crucible. The button that settles is transferred to the cupel and re-melted.

If the silver was not sufficiently dried by the heat of the fire, that which is contained in the upper part of the ampulla will appear black; this when melted will be consumed. When the lute, which was smeared round the lower part of the ampulla, has been removed, it is placed in the crucible and is re-melted, until at last there is no more appearance of black[13].

If to the first aqua the other which contains silver is to be added, it must be poured in before the powerful vapours appear, and the aqua gives off the oily substance, and the operculum becomes red; for he who pours in the aqua after the vapour appears causes a loss, because the aqua generally spurts out and the glass breaks. If the ampulla breaks when the gold is being parted from the silver or the silver from the aqua, the aqua will be absorbed by the sand or the lute or the bricks, whereupon, without any delay, the red hot coals should be taken out of the furnace and the fire extinguished. The sand and bricks after being crushed should be thrown into a copper vessel, warm water should be poured over them, and they should be put aside for the space of twelve hours; afterward the water should be strained through a canvas, and the canvas, since it contains silver, should be dried by the heat of the sun or the fire, and then placed in an earthen crucible and heated until the silver melts, this being poured out into an iron mould. The strained water should be poured into an ampulla and separated from the silver, of which it contains a minute portion; the sand should be mixed with litharge, glass-galls, argol, saltpetre, and salt, and heated in an earthen crucible. The button which settles at the bottom should be transferred to a cupel, and should be re-melted, in order that the lead may be separated from the silver. The lute, with lead added, should be heated in an earthen crucible, then re-melted in a cupel.

We also separate silver from gold by the same method when we assay them. For this purpose the alloy is first rubbed against a touchstone, in order to learn what proportion of silver there is in it; then as much silver as is necessary is added to the argentiferous gold, in a bes of which there must be less than a semi-uncia or a semi-uncia and a sicilicus[14] of copper. After lead has been added, it is melted in a cupel until the lead and the copper have exhaled, then the alloy of gold with silver is flattened out, and little tubes are made of the leaves; these are put into a glass ampulla, and strong aqua is poured over them two or three times. The tubes after this are absolutely pure, with the exception of only a quarter of a siliqua, which is silver; for only this much silver remains in eight unciae of gold[15].

As great expense is incurred in parting the metals by the methods that I have explained, as night vigils are necessary when aqua valens is made, and as generally much labour and great pains have to be expended on this matter, other methods for parting have been invented by clever men, which are less costly, less laborious, and in which there is less loss if through carelessness an error is made. There are three methods, the first performed with sulphur, the second with antimony, the third by means of some compound which consists of these or other ingredients.

A little of the regulus is taken from the crucible, but not from the gold lump which has settled at the bottom, and a drachma of it is put into each of the cupels, which contain an uncia of molten lead; there should be many of these cupels. In this way half a drachma of silver is made. As soon as the lead and copper have been separated from the silver, a third of it is thrown into a glass ampulla, and aqua valens is poured over it. By this method is shown whether the sulphur has parted all the gold from the silver, or not. If one wishes to know the size of the gold lump which has settled at the bottom of the crucible, an iron rod moistened with water is covered with chalk, and when the rod is dry it is pushed down straight into the crucible, and the rod remains bright to the height of the gold lump; the remaining part of the rod is coloured black by the regulus, which adheres to the rod if it is not quickly removed.

If when the rod has been extracted the gold is observed to be satisfactorily parted from the silver, the regulus is poured out, the gold button is taken out of the crucible, and in some clean place the regulus is chipped off from it, although it usually flies apart. The lump itself is reduced to granules, and for every libra of this gold they weigh out a quarter of a libra each of crushed sulphur and of granular copper, and all are placed together in an earthen crucible, not into a pot. When they are melted, in order that the gold may more quickly settle at the bottom, the powder which I have mentioned is added.

Although minute particles of gold appear to scintillate in the regulus of copper and silver, yet if all that are in a libra do not weigh as much as a single sesterce, then the sulphur has satisfactorily parted the gold from the silver; but if it should weigh a sesterce or more, then the regulus is thrown back again into the earthen crucible, and it is not advantageous to add sulphur, but only a little copper and powder, by which method a gold lump is again made to settle at the bottom; and this one is added to the other button which is not rich in gold.

When gold is parted from sixty-six librae of silver, the silver, copper, and sulphur regulus weighs one hundred and thirty-two librae. To separate the copper from the silver we require five hundred librae of lead, more or less, with which the regulus is melted in the second furnace. In this manner litharge and hearth-lead are made, which are re-smelted in the first furnace. The cakes that are made from these are placed in the third furnace, so that the lead may be separated from the copper and used again, for it contains very little silver. The crucibles and their covers are crushed, washed, and the sediment is melted together with litharge and hearth-lead.

Those who wish to separate all the silver from the gold by this method leave one part of gold to three of silver, and then reduce the alloy to granules. Then they place it in an ampulla, and by pouring aqua valens over it, part the gold from the silver, which process I explained in [Book VII].

If sulphur from the lye with which sal artificiosus is made, is strong enough to float an egg thrown into it, and is boiled until it no longer emits fumes, and melts when placed upon glowing coals, then, if such sulphur is thrown into the melted silver, it parts the gold from it.

To two librae and a half of such stibium are added two librae of argol and one libra of glass-galls, and they are melted in an earthen crucible, where a lump likewise settles at the bottom; this lump is melted in the cupel. Finally, the stibium with a little lead added, is melted in the cupel, in which, after all the rest has been consumed by the fire, the silver alone remains. If the stibium is not first melted in an earthen crucible with argol and glass-galls, before it is melted in the cupel, part of the silver is consumed, and is absorbed by the ash and powder of which the cupel is made.

The crucible in which the gold and silver alloy are melted with stibium, and also the cupel, are placed in a furnace, which is usually of the kind in which the air is drawn in through holes; or else they are placed in a goldsmith's forge.

Just as aqua valens poured over silver, from which the sulphur has parted the gold, shows us whether all has been separated or whether particles of gold remain in the silver; so do certain ingredients, if placed in the pot or crucible "alternately" with the gold, from which the silver has been parted by stibium, and heated, show us whether all have been separated or not.

We use cements[18] when, without stibium, we part silver or copper or both so ingeniously and admirably from gold. There are various cements. Some consist of half a libra of brick dust, a quarter of a libra of salt, an uncia of saltpetre, half an uncia of sal-ammoniac, and half an uncia of rock salt. The bricks or tiles from which the dust is made must be composed of fatty clays, free from sand, grit, and small stones, and must be moderately burnt and very old.

Another cement is made of a bes of brick dust, a third of rock salt, an uncia of saltpetre, and half an uncia of refined salt. Another cement is made of a bes of brick dust, a quarter of refined salt, one and a half unciae of saltpetre, an uncia of sal-ammoniac, and half an uncia of rock salt. Another has one libra of brick dust, and half a libra of rock salt, to which some add a sixth of a libra and a sicilicus of vitriol. Another is made of half a libra of brick dust, a third of a libra of rock salt, an uncia and a half of vitriol, and one uncia of saltpetre. Another consists of a bes of brick dust, a third of refined salt, a sixth of white vitriol[19], half an uncia of verdigris, and likewise half an uncia of saltpetre. Another is made of one and a third librae of brick dust, a bes of rock salt, a sixth of a libra and half an uncia of sal-ammoniac, a sixth and half an uncia of vitriol, and a sixth of saltpetre. Another contains a libra of brick dust, a third of refined salt, and one and a half unciae of vitriol.

Those ingredients above are peculiar to each cement, but what follows is common to all. Each of the ingredients is first separately crushed to powder; the bricks are placed on a hard rock or marble, and crushed with an iron implement; the other things are crushed in a mortar with a pestle; each is separately passed through a sieve. Then they are all mixed together, and are moistened with vinegar in which a little sal-ammoniac has been dissolved, if the cement does not contain any. But some workers, however, prefer to moisten the gold granules or gold-leaf instead.

The cement should be placed, alternately with the gold, in new and clean pots in which no water has ever been poured. In the bottom the cement is levelled with an iron implement, and afterward the gold granules or leaves are placed one against the other, so that they may touch it on all sides; then, again, a handful of the cement, or more if the pots are large, is thrown in and levelled with an iron implement; the granules and leaves are laid over this in the same manner, and this is repeated until the pot is filled. Then it is covered with a lid, and the place where they join is smeared over with artificial lute, and when this is dry the pots are placed in the furnace.

The gold granules or leaves and the cement, alternately placed in the pots, are heated by a gentle fire, gradually increasing for twenty-four hours, if the furnace was heated for two hours before the full pots were stood in it, and if this was not done, then for twenty-six hours. The fire should be increased in such a manner that the pieces of gold and the cement, in which is the potency to separate the silver and copper from the gold, may not melt, for in this case the labour and cost will be spent in vain; therefore, it is ample to have the fire hot enough that the pots always remain red. After so many hours all the burning wood should be drawn out of the furnace. Then the refractory bricks or tiles are removed from the top of the furnace, and the glowing pots are taken out with the tongs. The lids are removed, and if there is time it is well to allow the gold to cool by itself, for then there is less loss; but if time cannot be spared for that operation, the pieces of gold are immediately placed separately into a wooden or bronze vessel of water and gradually quenched, lest the cement which absorbs the silver should exhale it. The pieces of gold, and the cement adhering to them, when cooled or quenched, are rolled with a little mallet so as to crush the lumps and free the gold from the cement. Then they are sifted by a fine sieve, which is placed over a bronze vessel; in this manner the cement containing the silver or the copper or both, falls from the sieve into the bronze vessel, and the gold granules or leaves remain on it. The gold is placed in a vessel and again rolled with the little mallet, so that it may be cleansed from the cement which absorbs silver and copper.

The particles of cement, which have dropped through the holes of the sieve into the bronze vessel, are washed in a bowl, over a wooden tub, being shaken about with the hands, so that the minute particles of gold which have fallen through the sieve may be separated. These are again washed in a little vessel, with warm water, and scrubbed with a piece of wood or a twig broom, that the moistened cement may be detached. Afterward all the gold is again washed with warm water, and collected with a bristle brush, and should be washed in a copper full of holes, under which is placed a little vessel. Then it is necessary to put the gold on an iron plate, under which is a vessel, and to wash it with warm water. Finally, it is placed in a bowl, and, when dry, the granules or leaves are rubbed against a touchstone at the same time as a touch-needle, and considered carefully as to whether they be pure or alloyed. If they are not pure enough, the granules or the leaves, together with the cement which attracts silver and copper, are arranged alternately in layers in the same manner, and again heated; this is done as often as is necessary, but the last time it is heated as many hours as are required to cleanse the gold.

Some people add another cement to the granules or leaves. This cement lacks the ingredients of metalliferous origin, such as verdigris and vitriol, for if these are in the cement, the gold usually takes up a little of the base metal; or if it does not do this, it is stained by them. For this reason some very rightly never make use of cements containing these things, because brick dust and salt alone, especially rock salt, are able to extract all the silver and copper from the gold and to attract it to themselves.

It is not necessary for coiners to make absolutely pure gold, but to heat it only until such a fineness is obtained as is needed for the gold money which they are coining.

The gold is heated, and when it shows the necessary golden yellow colour and is wholly pure, it is melted and made into bars, in which case they are either prepared by the coiners with chrysocolla, which is called by the Moors borax, or are prepared with salt of lye made from the ashes of ivy or of other salty herbs.

The cement which has absorbed silver or copper, after water has been poured over it, is dried and crushed, and when mixed with hearth-lead and de-silverized lead, is smelted in the blast furnace. The alloy of silver and lead, or of silver and copper and lead, which flows out, is again melted in the cupellation furnace, in order that the lead and copper may be separated from the silver. The silver is finally thoroughly purified in the refining furnace, and in this practical manner there is no silver lost, or only a minute quantity.

There are besides this, certain other cements[20] which part gold from silver, composed of sulphur, stibium and other ingredients. One of these compounds consists of half an uncia of vitriol dried by the heat of the fire and reduced to powder, a sixth of refined salt, a third of stibium, half a libra of prepared sulphur (not exposed to the fire), one sicilicus of glass, likewise one sicilicus of saltpetre, and a drachma of sal-ammoniac.[21] The sulphur is prepared as follows: it is first crushed to powder, then it is heated for six hours in sharp vinegar, and finally poured into a vessel and washed with warm water; then that which settles at the bottom of the vessel is dried. To refine the salt it is placed in river water and boiled, and again evaporated. The second compound contains one libra of sulphur (not exposed to fire) and two librae of refined salt. The third compound is made from one libra of sulphur (not exposed to the fire), half a libra of refined salt, a quarter of a libra of sal-ammoniac, and one uncia of red-lead. The fourth compound consists of one libra each of refined salt, sulphur (not exposed to the fire) and argol, and half a libra of chrysocolla which the Moors call borax. The fifth compound has equal proportions of sulphur (not exposed to the fire), sal-ammoniac, saltpetre, and verdigris.

The silver which contains some portion of gold is first melted with lead in an earthen crucible, and they are heated together until the silver exhales the lead. If there was a libra of silver, there must be six drachmae of lead. Then the silver is sprinkled with two unciae of that powdered compound and is stirred; afterward it is poured into another crucible, first warmed and lined with tallow, and then violently shaken. The rest is performed according to the process I have already explained.

Gold may be parted without injury from silver goblets and from other gilt vessels and articles[22], by means of a powder, which consists of one part of sal-ammoniac and half a part of sulphur. The gilt goblet or other article is smeared with oil, and the powder is dusted on; the article is seized in the hand, or with tongs, and is carried to the fire and sharply tapped, and by this means the gold falls into water in vessels placed underneath, while the goblet remains uninjured.

Gold is also parted from silver on gilt articles by means of quicksilver. This is poured into an earthen crucible, and so warmed by the fire that the finger can bear the heat when dipped into it; the silver-gilt objects are placed in it, and when the quicksilver adheres to them they are taken out and placed on a dish, into which, when cooled, the gold falls, together with the quicksilver. Again and frequently the same silver-gilt object is placed in heated quicksilver, and the same process is continued until at last no more gold is visible on the object; then the object is placed in the fire, and the quicksilver which adheres to it is exhaled. Then the artificer takes a hare's foot, and brushes up into a dish the quicksilver and the gold which have fallen together from the silver article, and puts them into a cloth made of woven cotton or into a soft leather; the quicksilver is squeezed through one or the other into another dish.[23] The gold remains in the cloth or the leather, and when collected is placed in a piece of charcoal hollowed out, and is heated until it melts, and a little button is made from it. This button is heated with a little stibium in an earthen crucible and poured out into another little vessel, by which method the gold settles at the bottom, and the stibium is seen to be on the top; then the work is completed. Finally, the gold button is put in a hollowed-out brick and placed in the fire, and by this method the gold is made pure. By means of the above methods gold is parted from silver and also silver from gold.

Now I will explain the methods used to separate copper from gold[24]. The salt which we call sal-artificiosus,[25] is made from a libra each of vitriol, alum, saltpetre, and sulphur not exposed to the fire, and half a libra of sal-ammoniac; these ingredients when crushed are heated with one part of lye made from the ashes used by wool dyers, one part of unslaked lime, and four parts of beech ashes. The ingredients are boiled in the lye until the whole has been dissolved. Then it is immediately dried and kept in a hot place, lest it turn into oil; and afterward when crushed, a libra of lead-ash is mixed with it. With each libra of this powdered compound one and a half unciae of the copper is gradually sprinkled into a hot crucible, and it is stirred rapidly and frequently with an iron rod. When the crucible has cooled and been broken up, the button of gold is found.

The second method for parting is the following. Two librae of sulphur not exposed to the fire, and four librae of refined salt are crushed and mixed; a sixth of a libra and half an uncia of this powder is added to a bes of granules made of lead, and twice as much copper containing gold; they are heated together in an earthen crucible until they melt. When cooled, the button is taken out and purged of slag. From this button they again make granules, to a third of a libra of which is added half a libra of that powder of which I have spoken, and they are placed in alternate layers in the crucible; it is well to cover the crucible and to seal it up, and afterward it is heated over a gentle fire until the granules melt. Soon afterward, the crucible is taken off the fire, and when it is cool the button is extracted. From this, when purified and again melted down, the third granules are made, to which, if they weigh a sixth of a libra, is added one half an uncia and a sicilicus of the powder, and they are heated in the same manner, and the button of gold settles at the bottom of the crucible.

The third method is as follows. From time to time small pieces of sulphur, enveloped in or mixed with wax, are dropped into six librae of the molten copper, and consumed; the sulphur weighs half an uncia and a sicilicus. Then one and a half sicilici of powdered saltpetre are dropped into the same copper and likewise consumed; then again half an uncia and a sicilicus of sulphur enveloped in wax; afterward one and a half sicilici of lead-ash enveloped in wax, or of minium made from red-lead. Then immediately the copper is taken out, and to the gold button, which is now mixed with only a little copper, they add stibium to double the amount of the button; these are heated together until the stibium is driven off; then the button, together with lead of half the weight of the button, are heated in a cupel. Finally, the gold is taken out of this and quenched, and if there is a blackish colour settled in it, it is melted with a little of the chrysocolla which the Moors call borax; if too pale, it is melted with stibium, and acquires its own golden-yellow colour. There are some who take out the molten copper with an iron ladle and pour it into another crucible, whose aperture is sealed up with lute, and they place it over glowing charcoal, and when they have thrown in the powders of which I have spoken, they stir the whole mass rapidly with an iron rod, and thus separate the gold from the copper; the former settles at the bottom of the crucible, the latter floats on the top. Then the aperture of the crucible is opened with the red-hot tongs, and the copper runs out. The gold which remains is re-heated with stibium, and when this is exhaled the gold is heated for the third time in a cupel with a fourth part of lead, and then quenched.

The fourth method is to melt one and a third librae of the copper with a sixth of a libra of lead, and to pour it into another crucible smeared on the inside with tallow or gypsum; and to this is added a powder consisting of half an uncia each of prepared sulphur, verdigris, and saltpetre, and an uncia and a half of sal coctus. The fifth method consists of placing in a crucible one libra of the copper and two librae of granulated lead, with one and a half unciae of sal-artificiosus; they are at first heated over a gentle fire and then over a fiercer one. The sixth method consists in heating together a bes of the copper and one-sixth of a libra each of sulphur, salt, and stibium. The seventh method consists of heating together a bes of the copper and one-sixth each of iron scales and filings, salt, stibium, and glass-galls. The eighth method consists of heating together one libra of the copper, one and a half librae of sulphur, half a libra of verdigris, and a libra of refined salt. The ninth method consists of placing in one libra of the molten copper as much pounded sulphur, not exposed to the fire, and of stirring it rapidly with an iron rod; the lump is ground to powder, into which quicksilver is poured, and this attracts to itself the gold.

Gilded copper articles are moistened with water and placed on the fire, and when they are glowing they are quenched with cold water, and the gold is scraped off with a brass rod. By these practical methods gold is separated from copper.

Either copper or lead is separated from silver by the methods which I will now explain.[26] This is carried on in a building near by the works, or in the works in which the gold or silver ores or alloys are smelted. The middle wall of such a building is twenty-one feet long and fifteen feet high, and from this a front wall is distant fifteen feet toward the river; the rear wall is nineteen feet distant, and both these walls are thirty-six feet long and fourteen feet high; a transverse wall extends from the end of the front wall to the end of the rear wall; then fifteen feet back a second transverse wall is built out from the front wall to the end of the middle wall. In that space which is between those two transverse walls are set up the stamps, by means of which the ores and the necessary ingredients for smelting are broken up. From the further end of the front wall, a third transverse wall leads to the other end of the middle wall, and from the same to the end of the rear wall. The space between the second and third transverse walls, and between the rear and middle long walls, contains the cupellation furnace, in which lead is separated from gold or silver. The vertical wall of its chimney is erected upon the middle wall, and the sloping chimney-wall rests on the beams which extend from the second transverse wall to the third; these are so located that they are at a distance of thirteen feet from the middle long wall and four from the rear wall, and they are two feet wide and thick. From the ground up to the roof-beams is twelve feet, and lest the sloping chimney-wall should fall down, it is partly supported by means of many iron rods, and partly by means of a few tie-beams covered with lute, which extend from the small beams of the sloping chimney-wall to the beams of the vertical chimney-wall. The rear roof is arranged in the same way as the roof of the works in which ore is smelted. In the space between the middle and the front long walls and between the second[27] and the third transverse walls are the bellows, the machinery for depressing and the instrument for raising them. A drum on the axle of a water-wheel has rundles which turn the toothed drum of an axle, whose long cams depress the levers of the bellows, and also another toothed drum on an axle, whose cams raise the tappets of the stamps, but in the opposite direction. So that if the cams which depress the levers of the bellows turn from north to south, the cams of the stamps turn from south to north.

A dome which has the shape of half a sphere covers the crucible. It consists of iron bands and of bars and of a lid. There are three bands, each about a palm wide and a digit thick; the lowest is at a distance of one foot from the middle one, and the middle one a distance of two feet from the upper one. Under them are eighteen iron bars fixed by iron rivets; these bars are of the same width and thickness as the bands, and they are of such a length, that curving, they reach from the lower band to the upper, that is two feet and three palms long, while the dome is only one foot and three palms high. All the bars and bands of the dome have iron plates fastened on the underside with iron wire. In addition, the dome has four apertures; the rear one, which is situated opposite the channel through which the litharge flows out, is two feet wide at the bottom; toward the top, since it slopes gently, it is narrower, being a foot, three palms, and a digit wide; there is no bar at this place, for the aperture extends from the upper band to the middle one, but not to the lower one. The second aperture is situated above the channel, is two and a half feet wide at the bottom, and two feet and a palm at the top; and there is likewise no bar at this point; indeed, not only does the bar not extend to the lower band, but the lower band itself does not extend over this part, in order that the master can draw the litharge out of the crucible. There are besides, in the wall which protects the principal wall against the heat, near where the nozzles of the bellows are situated, two apertures, three palms wide and about a foot high, in the middle of which two rods descend, fastened on the inside with plates. Near these apertures are placed the nozzles of the bellows, and through the apertures extend the pipes in which the nozzles of the bellows are set. These pipes are made of iron plates rolled up; they are two palms three digits long, and their inside diameter is three and a half digits; into these two pipes the nozzles of the bellows penetrate a distance of three digits from their valves. The lid of the dome consists of an iron band at the bottom, two digits wide, and of three curved iron bars, which extend from one point on the band to the point opposite; they cross each other at the top, where they are fixed by means of iron rivets. On the under side of the bars there are likewise plates fastened by rivets; each of the plates has small holes the size of a finger, so that the lute will adhere when the interior is lined. The dome has three iron rings engaged in wide holes in the heads of iron claves, which fasten the bars to the middle band at these points. Into these rings are fastened the hooks of the chains with which the dome is raised, when the master is preparing the crucible.

On the sole and the copper plates and the rock of the furnace, lute mixed with straw is placed to a depth of three digits, and it is pounded with a wooden rammer until it is compressed to a depth of one digit only. The rammer-head is round and three palms high, two palms wide at the bottom, and tapering upward; its handle is three feet long, and where it is set into the rammer-head it is bound around with an iron band. The top of the stonework in which the dome rests is also covered with lute, likewise mixed with straw, to the thickness of a palm. All this, as soon as it becomes loosened, must be repaired.

An iron plate is set in the ground under the channel, and upon this is placed a wooden block, three feet and a palm long, a foot and two palms and as many digits wide at the back, and two palms and as many digits wide in front; on the block of wood is placed a stone, and over it an iron plate similar to the bottom one, and upon this he puts a basketful of charcoal, and also an iron shovelful of burning charcoals. The crucible is heated in an hour, and then, with the hooked bar with which the litharge is drawn off, he stirs the remainder of the charcoal about. This hook is a palm long and three digits wide, has the form of a double triangle, and has an iron handle four feet long, into which is set a wooden one six feet long. There are some who use instead a simple hooked bar. After about an hour's time, he stirs the charcoal again with the bar, and with the shovel throws into the crucible the burning charcoals lying in the channel; then again, after the space of an hour, he stirs the burning charcoals with the same bar. If he did not thus stir them about, some blackness would remain in the crucible and that part would be damaged, because it would not be sufficiently dried. Therefore the assistant stirs and turns the burning charcoal that it may be entirely burnt up, and so that the crucible may be well heated, which takes three hours; then the crucible is left quiet for the remaining two hours.

When the hour of eleven has struck, he sweeps up the charcoal ashes with a broom and throws them out of the crucible. Then he climbs on to the dome, and passing his hand in through its opening, and dipping an old linen rag in a bucket of water mixed with ashes, he moistens the whole of the crucible and sweeps it. In this way he uses two bucketsful of the mixture, each holding five Roman sextarii,[28] and he does this lest the crucible, when the metals are being parted, should break open; after this he rubs the crucible with a doe skin, and fills in the cracks. Then he places at the left side of the channel, two fragments of hearth-lead, laid one on the top of the other, so that when partly melted they remain fixed and form an obstacle, that the litharge will not be blown about by the wind from the bellows, but remain in its place. It is expedient, however, to use a brick in the place of the hearth-lead, for as this gets much hotter, therefore it causes the litharge to form more rapidly. The crucible in its middle part is made two palms and as many digits deeper.[29]

There are some who having thus prepared the crucible, smear it over with incense[30], ground to powder and dissolved in white of egg, soaking it up in a sponge and then squeezing it out again; there are others who smear over it a liquid consisting of white of egg and double the amount of bullock's blood or marrow. Some throw lime into the crucible through a sieve.

Afterward the master of the works weighs the lead with which the gold or silver or both are mixed, and he sometimes puts a hundred centumpondia[31] into the crucible, but frequently only sixty, or fifty, or much less. After it has been weighed, he strews about in the crucible three small bundles of straw, lest the lead by its weight should break the surface. Then he places in the channel several cakes of lead alloy, and through the aperture at the rear of the dome he places some along the sides; then, ascending to the opening at the top of the dome, he arranges in the crucible round about the dome the cakes which his assistant hands to him, and after ascending again and passing his hands through the same aperture, he likewise places other cakes inside the crucible. On the second day those which remain he, with an iron fork, places on the wood through the rear aperture of the dome.

When the cakes have been thus arranged through the hole at the top of the dome, he throws in charcoal with a basket woven of wooden twigs. Then he places the lid over the dome, and the assistant covers over the joints with lute. The master himself throws half a basketful of charcoal into the crucible through the aperture next to the nozzle pipe, and prepares the bellows, in order to be able to begin the second operation on the morning of the following day. It takes the space of one hour to carry out such a piece of work, and at twelve all is prepared. These hours all reckoned up make a sum of eight hours.

Now it is time that we should come to the second operation. In the morning the workman takes up two shovelsful of live charcoals and throws them into the crucible through the aperture next to the pipes of the nozzles; then through the same hole he lays upon them small pieces of fir-wood or of pitch pine, such as are generally used to cook fish. After this the water-gates are opened, in order that the machine may be turned which depresses the levers of the bellows. In the space of one hour the lead alloy is melted; and when this has been done, he places four sticks of wood, twelve feet long, through the hole in the back of the dome, and as many through the channel; these sticks, lest they should damage the crucible, are both weighted on the ends and supported by trestles; these trestles are made of a beam, three feet long, two palms and as many digits wide, two palms thick, and have two spreading legs at each end. Against the trestle, in front of the channel, there is placed an iron plate, lest the litharge, when it is extracted from the furnace, should splash the smelter's shoes and injure his feet and legs. With an iron shovel or a fork he places the remainder of the cakes through the aperture at the back of the dome on to the sticks of wood already mentioned.

The native silver, or silver glance, or grey silver, or ruby silver, or any other sort, when it has been flattened out[32], and cut up, and heated in an iron crucible, is poured into the molten lead mixed with silver, in order that impurities may be separated. As I have often said, this molten lead mixed with silver is called stannum[33].

If it be difficult to separate the lead from the silver, he throws copper and charcoal dust into the molten silver-lead alloy. If the alloy of argentiferous gold and lead, or the silver-lead alloy, contains impurities from the ore, then he throws in either equal portions of argol and Venetian glass or of sal-ammoniac, or of Venetian glass and of Venetian soap; or else unequal portions, that is, two of argol and one of iron rust; there are some who mix a little saltpetre with each compound. To one centumpondium of the alloy is added a bes or a libra and a third of the powder, according to whether it is more or less impure. The powder certainly separates the impurities from the alloy. Then, with a kind of rabble he draws out through the channel, mixed with charcoal, the scum, as one might say, of the lead; the lead makes this scum when it becomes hot, but that less of it may be made it must be stirred frequently with the bar.

Within the space of a quarter of an hour the crucible absorbs the lead; at the time when it penetrates into the crucible it leaps and bubbles. Then the master takes out a little lead with an iron ladle, which he assays, in order to find what proportion of silver there is in the whole of the alloy; the ladle is five digits wide, the iron part of its handle is three feet long and the wooden part the same. Afterward, when they are heated, he extracts with a bar the litharge which comes from the lead and the copper, if there be any of it in the alloy. Wherefore, it might more rightly be called spuma of lead than of silver[34]. There is no injury to the silver, when the lead and copper are separated from it. In truth the lead becomes much purer in the crucible of the other furnace, in which silver is refined. In ancient times, as the author Pliny[35] relates, there was under the channel of the crucible another crucible, and the litharge flowed down from the upper one into the lower one, out of which it was lifted up and rolled round with a stick in order that it might be of moderate weight. For which reason, they formerly made it into small tubes or pipes, but now, since it is not rolled round a stick, they make it into bars.

If there be any danger that the alloy might flow out with the litharge, the foreman keeps on hand a piece of lute, shaped like a cylinder and pointed at both ends; fastening this to a hooked bar he opposes it to the alloy so that it will not flow out.

The ashes which pass through the sieve are of the same use as they were at first, for, indeed, from these and pulverised bones they make the cupels. Finally, when much of it has accumulated, the yellow pompholyx adhering to the walls of the furnace, and likewise to those rings of the dome near the apertures, is cleared away.

Then boards are laid upon the lower small cross-beam, and at a height of two palms above these there is a small square iron axle, the sides of which are two digits wide; both ends of it are round and turn in bronze or iron bearings, one of these bearings being fastened in the crane-post, the other in the upright timber. About each end of the small axle is a wooden disc, of three palms and a digit radius and one palm thick, covered on the rim with an iron band; these two discs are distant two palms and as many digits from each other, and are joined with five rundles; these rundles are two and a half digits thick and are placed three digits apart. Thus a drum is made, which is a palm and a digit distant from the upright timber, but further from the crane-post, namely, a palm and three digits. At a height of a foot and a palm above this little axle is a second small square iron axle, the thickness of which is three digits; this one, like the first one, turns in bronze or iron bearings. Around it is a toothed wheel, composed of two discs a foot three palms in diameter, a palm and two digits thick; on the rim of this there are twenty-three teeth, a palm wide and two digits thick; they protrude a palm from the wheel and are three digits apart. And around this same axle, at a distance of two palms and as many digits toward the upright timber, is another disc of the same diameter as the wheel and a palm thick; this turns in a hollowed-out place in the upright timber. Between this disc and the disc of the toothed wheel another drum is made, having likewise five rundles. There is, in addition to this second axle, at a height of a cubit above it, a small wooden axle, the journals of which are of iron; the ends are bound round with iron rings so that the journals may remain firmly fixed, and the journals, like the little iron axles, turn in bronze or iron bearings. This third axle is at a distance of about a cubit from the upper small cross-beam; it has, near the upright timber, a toothed wheel two and a half feet in diameter, on the rim of which are twenty-seven teeth; the other part of this axle, near the crane-post, is covered with iron plates, lest it should be worn away by the chain which winds around it. The end link of the chain is fixed in an iron pin driven into the little axle; this chain passes out of the frame and turns over a little pulley set between the beams of the crane-arm.

Above the frame, at a height of a foot and a palm, is the crane-arm. This consists of two beams fifteen feet long, three palms wide, and two thick, mortised into the crane-post, and they protrude a cubit from the back of the crane-post and are fastened together. Moreover, they are fastened by means of a wooden pin which penetrates through them and the crane-post; this pin has at the one end a broad head, and at the other a hole, through which is driven an iron bolt, so that the beams may be tightly bound into the crane-post. The beams of the crane-arm are supported and stayed by means of two oblique beams, six feet and two palms long, and likewise two palms wide and thick; these are mortised into the crane-post at their lower ends, and their upper ends are mortised into the beams of the crane-arm at a point about four feet from the crane-post, and they are fastened with iron nails. At the back of the upper end of these oblique beams, toward the crane-post, is an iron staple, fastened into the lower sides of the beams of the crane-arm, in order that it may hold them fast and bind them. The outer end of each beam of the crane-arm is set in a rectangular iron plate, and between these are three rectangular iron plates, fixed in such a manner that the beams of the crane-arm can neither move away from, nor toward, each other. The upper sides of these crane-arm beams are covered with iron plates for a length of six feet, so that a trolley can move on it.

The body of the trolley is made of wood from the Ostrya or any other hard tree, and is a cubit long, a foot wide, and three palms thick; on both edges of it the lower side is cut out to a height and width of a palm, so that the remainder may move backward and forward between the two beams of the crane-arm; at the front, in the middle part, it is cut out to a width of two palms and as many digits, that a bronze pulley, around a small iron axle, may turn in it. Near the corners of the trolley are four holes, in which as many small wheels travel on the beams of the crane-arm. Since this trolley, when it travels backward and forward, gives out a sound somewhat similar to the barking of a dog, we have given it this name[38]. It is propelled forward by means of a crank, and is drawn back by means of a chain. There is an iron hook whose ring turns round an iron pin fastened to the right side of the trolley, which hook is held by a sort of clavis, which is fixed in the right beam of the crane-arm.

At the end of the crane-post is a bronze pulley, the iron axle of which is fastened in the beams of the crane-arm, and over which the chain passes as it comes from the frame, and then, penetrating through the hollow in the top of the trolley, it reaches to the little bronze pulley of the trolley, and passing over this it hangs down. A hook on its end engages a ring, in which are fixed the top links of three chains, each six feet long, which pass through the three iron rings fastened in the holes of the claves which are fixed into the middle iron band of the dome, of which I have spoken.

Therefore when the master wishes to lift the dome by means of the crane, the assistant fits over the lower small iron axle an iron crank, which projects from the upright beam a palm and two digits; the end of the little axle is rectangular, and one and a half digits wide and one digit thick; it is set into a similar rectangular hole in the crank, which is two digits long and a little more than a digit wide. The crank is semi-circular, and one foot three palms and two digits long, as many digits wide, and one digit thick. Its handle is straight and round, and three palms long, and one and a half digits thick. There is a hole in the end of the little axle, through which an iron pin is driven so that the crank may not come off. The crane having four drums, two of which are rundle-drums and two toothed-wheels, is more easily moved than another having two drums, one of which has rundles and the other teeth.

Many, however, use only a simple contrivance, the pivots of whose crane-post turn in the same manner, the one in an iron socket, the other in a ring. There is a crane-arm on the crane-post, which is supported by an oblique beam; to the head of the crane-arm a strong iron ring is fixed, which engages a second iron ring. In this iron ring a strong wooden lever-bar is fastened firmly, the head of which is bound by a third iron ring, from which hangs an iron hook, which engages the rings at the ends of the chains from the dome. At the other end of the lever-bar is another chain, which, when it is pulled down, raises the opposite end of the bar and thus the dome; and when it is relaxed the dome is lowered.

When the silver is seen to be thoroughly refined, the artificer removes the coals from the test with a shovel. Soon afterward he draws water in a copper ladle, which has a wooden handle four feet long; it has a small hole at a point half-way between the middle of the bowl and the edge, through which a hemp seed just passes. He fills this ladle three times with water, and three times it all flows out through the hole on to the silver, and slowly quenches it; if he suddenly poured much water on it, it would burst asunder and injure those standing near. The artificer has a pointed iron bar, three feet long, which has a wooden handle as many feet long, and he puts the end of this bar into the test in order to stir it. He also stirs it with a hooked iron bar, of which the hook is two digits wide and a palm deep, and the iron part of its handle is three feet long and the wooden part the same. Then he removes the test from the hearth with a shovel or a fork, and turns it over, and by this means the silver falls to the ground in the shape of half a sphere; then lifting the cake with a shovel he throws it into a tub of water, where it gives out a great sound. Or else, having lifted the cake of silver with a fork, he lays it upon the iron implement similar to tongs, which are placed across a tub full of water; afterward, when cooled, he takes it from the tub again and lays it on the block made of hard wood and beats it with a hammer, in order to break off any of the powder from the test which adheres to it. The cake is then placed on the implement similar to tongs, laid over the tub full of water, and cleaned with a bundle of brass wire dipped into the water; this operation of beating and cleansing is repeated until it is all clean. Afterward he places it on an iron grate or tripod; the tripod is a palm and two digits high, one and a half digits wide, and its span is two palms wide; then he puts burning charcoal under the tripod or grate, in order again to dry the silver that was moistened by the water. Finally, the Royal Inspector[42] in the employment of the King or Prince, or the owner, lays the silver on a block of wood, and with an engraver's chisel he cuts out two small pieces, one from the under and the other from the upper side. These are tested by fire, in order to ascertain whether the silver is thoroughly refined or not, and at what price it should be sold to the merchants. Finally he impresses upon it the seal of the King or the Prince or the owner, and, near the same, the amount of the weight.

END OF BOOK X.