FOOTNOTES:

[Pg 219][1] We have but little record of anything which could be called "assaying" among the Greeks and Romans. The fact, however, that they made constant use of the touchstone (see [note 37, p. 252]) is sufficient proof that they were able to test the purity of gold and silver. The description of the touchstone by Theophrastus contains several references to "trial" by fire (see [note 37, p. 252]). They were adepts at metal working, and were therefore familiar with melting metals on a small scale, with the smelting of silver, lead, copper, and tin ores (see [note 1, p. 353]) and with the parting of silver and lead by cupellation. Consequently, it would not require much of an imaginative flight to conclude that there existed some system of tests of ore and metal values by fire. Apart from the statement of Theophrastus referred to, the first references made to anything which might fill the rôle of assaying are from the Alchemists, particularly Geber (prior to 1300), for they describe methods of solution, precipitation, distillation, fusing in crucibles, cupellation, and of the parting of gold and silver by acid and by sulphur, antimony, or cementation. However, they were not bent on [Pg 220]determining quantitative values, which is the fundamental object of the assayer's art, and all their discussion is shrouded in an obscure cloak of gibberish and attempted mysticism. Nevertheless, therein lies the foundation of many cardinal assay methods, and even of chemistry itself.

The first explicit records of assaying are the anonymous booklets published in German early in the 16th Century under the title Probierbüchlein. Therein the art is disclosed well advanced toward maturity, so far as concerns gold and silver, with some notes on lead and copper. We refer the reader to [Appendix B] for fuller discussion of these books, but we may repeat here that they are a collection of disconnected recipes lacking in arrangement, the items often repeated, and all apparently the inheritance of wisdom passed from father to son over many generations. It is obviously intended as a sort of reminder to those already skilled in the art, and would be hopeless to a novice. Apart from some notes in Biringuccio (Book III, Chaps. 1 and 2) on assaying gold and silver, there is nothing else prior to De Re Metallica. Agricola was familiar with these works and includes their material in this chapter. The very great advance which his account represents can only be appreciated by comparison, but the exhaustive publication of other works is foreign to the purpose of these notes. Agricola introduces system into the arrangement of his materials, describes implements, and gives a hundred details which are wholly omitted from the previous works, all in a manner which would enable a beginner to learn the art. Furthermore, the assaying of lead, copper, tin, quicksilver, iron, and bismuth, is almost wholly new, together with the whole of the argument and explanations. We would call the attention of students of the history of chemistry to the general oversight of these early 16th Century attempts at analytical chemistry, for in them lie the foundations of that science. The statement sometimes made that Agricola was the first assayer, is false if for no other reason than that science does not develop with such strides at any one human hand. He can, however, fairly be accounted as the author of the first proper text-book upon assaying. Those familiar with the art will be astonished at the small progress made since his time, for in his pages appear most of the reagents and most of the critical operations in the dry analyses of gold, silver, lead, copper, tin, bismuth, quicksilver, and iron of to-day. Further, there will be recognised many of the "kinks" of the art used even yet, such as the method of granulation, duplicate assays, the "assay ton" method of weights, the use of test lead, the introduction of charges in leaf lead, and even the use of beer instead of water to damp bone-ash.

The following table is given of the substances mentioned requiring some comment, and the terms adopted in this book, with notes for convenience in reference. The German terms are either from Agricola's Glossary of De Re Metallica, his Interpretatio, or the German Translation. We have retained the original German spelling. The fifth column refers to the page where more ample notes are given:—

Terms adopted.	Latin.	German.	Remarks.	Further Notes.
Alum	Alumen	Alaun	Either potassium or ammonia alum	p. [564]
Ampulla	Ampulla	Kolb	A distillation jar
Antimony	Stibium	Spiesglas	Practically always antimony sulphide	p. [428]
Aqua valens or aqua	Aqua valens	Scheidewasser	Mostly nitric acid	p. [439]
Argol	Feces vini siccae	Die weinheffen	Crude tartar	p. [234]
Ash of lead	Nigrum plumbum cinereum		Artificial lead sulphide	p. [237]
Ash of musk ivy (Salt made from)	Sal ex anthyllidis cinere factus	Salalkali	Mostly potash	p. [560]
Ashes which wool-dyers use	Cineres quo infectores lanarum		Mostly potash	p. [559]
Assay	Venas experiri	Probiren
Assay furnace	Fornacula	Probir ofen	"Little" furnace
Azure	Caeruleum	Lasur	Partly copper carbonate (azurite) partly silicate	p. [110]
[Pg 221]Bismuth	Plumbum Cinereum	Wismut	Bismuth	p. [433]
Bitumen	Bitumen	Bergwachs		p. [581]
Blast furnace	Prima fornax	Schmeltzofen
Borax	Chrysocolla ex nitro confecta; chrysocolla quam boracem nominant	Borras; Tincar		p. [560]
Burned alum	Alumen coctum	Gesottener alaun	Probably dehydrated alum	p. [565]
Cadmia (see [note 8, p. 112])			(1) Furnace accretions (2) Calamine (3) Zinc blende (4) Cobalt arsenical sulphides	p. [112]
Camphor	Camphora	Campffer		p. [238]
Chrysocolla called borax (see [borax])
Chrysocolla (copper mineral)	Chrysocolla	Berggrün und Schifergrün	Partly chrysocolla, partly malachite	p. [110]
Copper filings	Aeris scobs elimata	Kupferfeilich	Apparently finely divided copper metal	p. [233]
Copper flowers	Aeris flos	Kupferbraun	Cupric oxide	p. [538]
Copper scales	Aeris squamae	Kupfer hammerschlag oder kessel braun	Probably cupric oxide
Copper minerals (see [note 8, p. 109])
Crucible (triangular)	Catillus triangularis	Dreieckichtschirbe	See illustration	p. [229]
Cupel	Catillus cinereus	Capelle
Cupellation furnace	Secunda fornax	Treibherd
Flux	Additamentum	Zusetze		p. [232]
Furnace accretions	Cadmia fornacum	Mitlere und obere offenbrüche
Galena	Lapis plumbarius	Glantz	Lead sulphide	p. [110]
Glass-gall	Recrementum vitri	Glassgallen	Skimmings from glass melting	p. [235]
Grey antimony or stibium	Stibi or stibium	Spiesglas	Antimony sulphide, stibnite	p. [428]
Hearth-lead	Molybdaena	Herdplei	The saturated furnace bottoms from cupellation	p. [476]
Hoop (iron)	Circulus ferreus	Ring	A forge for crucibles	p. [226]
Iron filings	Ferri scobs elimata	Eisen feilich	Metallic iron
Iron scales	Squamae ferri	Eisen hammerschlag	Partly iron oxide
Iron slag	Recrementum ferri	Sinder
Lead ash	Cinis plumbi nigri	Pleiasche	Artificial lead sulphide	p. [237]
Lead granules	Globuli plumbei	Gekornt plei	Granulated lead
Lead ochre	Ochra plumbaria	Pleigeel	Modern massicot (PbO)	p. [232]
Lees of aqua which separates gold from silver	Feces aquarum quae aurum ab argento secernunt	Scheidewasser heffe	Uncertain	p. [234]
Dried lees of vinegar	Siccae feces aceti	Heffe des essigs	Argol	p. [234]
Dried lees of wine	Feces vini siccae	Wein heffen	Argol	p. [234]
[Pg 222]Limestone	Saxum calcis	Kalchstein
Litharge	Spuma argenti	Glette
Lye	Lixivium	Lauge durch asschen gemacht	Mostly potash	p. [233]
Muffle	Tegula	Muffel	Latin, literally "Roof-tile"
Operculum	Operculum	Helm oder alembick	Helmet or cover for a distillation jar
Orpiment	Auripigmentum	Operment	Yellow sulphide of arsenic (As₂S₃)	p. [111]
Pyrites	Pyrites	Kis	Rather a genus of sulphides, than iron pyrite in particular	p. [112]
Pyrites (Cakes from)	Panes ex pyrite conflati	Stein	Iron or Copper matte	p. [350]
Realgar	Sandaraca	Rosgeel	Red sulphide of arsenic (AsS)	p. [111]
Red lead	Minium	Menning	Pb₃O₄	p. [232]
Roasted copper	Aes ustum	Gebrandt kupffer	Artificial copper sulphide (?)	p. [233]
Salt	Sal	Saltz	NaCl	p. [233]
Salt (Rock)	Sal fossilis	Berg saltz	NaCl	p. [233]
Sal artificiosus	Sal artificiosus		A stock flux?	p. [236]
Sal ammoniac	Sal ammoniacus	Salarmoniac	NH₄Cl	p. [560]
Saltpetre	Halinitrum	Salpeter	KNO₃	p. [561]
Salt (refined)	Sal facticius purgatus		NaCl
Sal tostus	Sal tostus	Geröst saltz	Apparently simply heated or melted common salt	p. [233]
Sal torrefactus	Sal torrefactus	Geröst saltz		p. [233]
Salt (melted)	Sal liquefactus	Geflossen saltz	Melted salt or salt glass	p. [233]
Scorifier	Catillus fictilis	Scherbe
Schist	Saxum fissile	Schifer
Silver minerals (see [note 8, p. 108])
Slag	Recrementum	Schlacken
Soda	Nitrum		Mostly soda from Egypt, Na₂CO₃	p. [558]
Stones which easily melt	Lapides qui facile igni liquescunt	Flüs	Quartz and fluorspar	p. [380]
Sulphur	Sulfur	Schwefel		p. [579]
Tophus	Tophus	Topstein	Marl?	p. [233]
Touchstone	Coticula	Goldstein
Venetian glass	Venetianum vitrum
Verdigris	Aerugo	Grünspan oder Spanschgrün	Copper sub-acetate	p. [440]
Vitriol	Atramentum sutorium	Kupferwasser	Mostly FeSO₄	p. [572]
White schist	Saxum fissile album	Weisser schifer		p. [234]
Weights (see [Appendix]).

[Pg 224][2] Crudorum,—unbaked?

[3] This reference is not very clear. Apparently the names refer to the German terms probier ofen and windt ofen.

[Pg 226][4] Circulus. This term does not offer a very satisfactory equivalent, as such a furnace has no distinctive name in English. It is obviously a sort of forge for fusing in crucibles.

[Pg 230][5] Spissa,—"Dry." This term is used in contra-distinction to pingue, unctuous or "fatty."

[Pg 232][6] Additamenta,—"Additions." Hence the play on words.

We have adopted "flux" because the old English equivalent for all these materials was "flux," although in modern nomenclature the term is generally restricted to those substances which, by chemical combination in the furnace, lower the melting point of some of the charge. The "additions" of Agricola, therefore, include reducing, oxidizing, sulphurizing, desulphurizing, and collecting agents as well as fluxes. A critical examination of the fluxes mentioned in the next four pages gives point to the Author's assertion that "some are of a very complicated nature." However, anyone of experience with home-taught assayers has come in contact with equally extraordinary combinations. The four orders of "additions" enumerated are quite impossible to reconcile from a modern metallurgical point of view.

[7] Minium secundarium. (Interpretatio,—menning. Pb₃O₄). Agricola derived his Latin term from Pliny. There is great confusion in the ancient writers on the use of the word minium, for prior to the Middle Ages it was usually applied to vermilion derived from cinnabar. Vermilion was much adulterated with red-lead, even in Roman times, and finally in later centuries the name came to be appropriated to the lead product. Theophrastus (103) mentions a substitute for vermilion, but, in spite of commentators, there is no evidence that it was red-lead. The first to describe the manufacture of real red-lead was apparently Vitruvius (VII, 12), who calls it sandaraca (this name was usually applied to red arsenical sulphide), and says: "White-lead is heated in a furnace and by the force of the fire becomes red lead. This invention was the result of observation in the case of an accidental fire, and by the process a much better material is obtained than from the mines." He describes minium as the product from cinnabar. Dioscorides (V, 63), after discussing white-lead, says it may be burned until it becomes the colour of sandaracha, and is called sandyx. He also states (V, 69) that those are deceived who consider cinnabar to be the same as minium, for minium is made in Spain out of stone mixed with silver sands. Therefore he is not in agreement with Vitruvius and Pliny on the use of the term. Pliny (XXXIII, 40) says: "These barren stones (apparently lead ores barren of silver) may be recognised by their colour; it is only in the furnace that they turn red. After being roasted it is pulverized and is minium secundarium. It is known to few and is very inferior to the natural kind made from those sands we have mentioned (cinnabar). It is with this that the genuine minium is adulterated in the works of the Company." This proprietary company who held a monopoly of the Spanish quicksilver mines, "had many methods of adulterating it (minium)—a source of great plunder to the Company." Pliny also describes the making of red lead from white.

[8] Ochra plumbaria. (Interpretatio,—pleigeel; modern German,—Bleigelb). The German term indicates that this "Lead Ochre," a form of PbO, is what in the English trade is known as massicot, or masticot. This material can be a partial product from almost any cupellation where oxidation takes place below the melting point of the oxide. It may have been known to the Ancients among the various species into which they divided [Pg 233]litharge, but there is no valid reason for assigning to it any special one of their terms, so far as we can see.

[9] There are four forms of copper named as re-agents by Agricola:

Copper filings	Aeris scobs elimata.
Copper scales	Aeris squamae.
Copper flowers	Aeris flos.
Roasted copper	Aes ustum.

The first of these was no doubt finely divided copper metal; the second, third, and fourth were probably all cupric oxide. According to Agricola (De Nat. Fos., p. 352), the scales were the result of hammering the metal; the flowers came off the metal when hot bars were quenched in water, and a third kind were obtained from calcining the metal. "Both flowers (flos) and hammer-scales (squama) have the same properties as crematum copper.... The particles of flower copper are finer than scales or crematum copper." If we assume that the verb uro used in De Re Metallica is of the same import as cremo in the De Natura Fossilium, we can accept this material as being merely cupric oxide, but the aes ustum of Pliny—Agricola's usual source of technical nomenclature—is probably an artificial sulphide. Dioscorides (V, 47), who is apparently the source of Pliny's information, says:—"Of chalcos cecaumenos, the best is red, and pulverized resembles the colour of cinnabar; if it turns black, it is over-burnt. It is made from broken ship nails put into a rough earthen pot, with alternate layers of equal parts of sulphur and salt. The opening should be smeared with potter's clay and the pot put in the furnace until it is thoroughly heated," etc. Pliny (XXXIV, 23) states: "Moreover Cyprian copper is roasted in crude earthen pots with an equal amount of sulphur; the apertures of the pots are well luted, and they are kept in the furnace until the pot is thoroughly heated. Some add salt, others use alumen instead of sulphur, others add nothing, but only sprinkle it with vinegar."

[10] The reader is referred to [note 6, p. 558], for more ample discussion of the alkalis. Agricola gives in this chapter four substances of that character:

Soda (nitrum). Lye. "Ashes which wool-dyers use." "Salt made from the ashes of musk ivy."

The last three are certainly potash, probably impure. While the first might be either potash or soda, the fact that the last three are mentioned separately, together with other evidence, convinces us that by the first is intended the nitrum so generally imported into Europe from Egypt during the Middle Ages. This imported salt was certainly the natural bicarbonate, and we have, therefore, used the term "soda."

[11] In this chapter are mentioned seven kinds of common salt:

Salt	Sal.
Rock salt	Sal fossilis.
"Made" salt	Sal facticius.
Refined salt	Sal purgatius.
Melted salt	Sal liquefactus.

And in addition sal tostus and sal torrefactus. Sal facticius is used in distinction from rock-salt. The melted salt would apparently be salt-glass. What form the sal tostus and sal torrefactus could have we cannot say, however, but they were possibly some form of heated salt; they may have been combinations after the order of sal artificiosus (see p. [236]).

[12] "Stones which easily melt in hot furnaces and sand which is made from them" (lapides qui in ardentibus fornacibus facile liquescunt arenae ab eis resolutae). These were probably quartz in this instance, although fluorspar is also included in this same genus. For fuller discussion see note on p. [380].

[13] Tophus. (Interpretatio, Toffstein oder topstein). According to Dana (Syst. of Min., p. 678), the German topfstein was English potstone or soapstone, a magnesian silicate. It is scarcely possible, however, that this is what Agricola meant by this term, for such a substance would be highly infusible. Agricola has a good deal to say about this mineral in De Natura Fossilium (p. 189 and 313), and from these descriptions it would seem to be a tufaceous limestone of various sorts, embracing some marls, stalagmites, calcareous sinter, etc. He states: "Generally fire does not melt it, but makes it harder and breaks it into powder. Tophus is said to be a stone found in caverns, made from the dripping of stone juice solidified by cold ... sometimes it is found containing many shells, and likewise the impressions of alder leaves; our people make lime by burning it." Pliny, upon whom Agricola depends largely for his nomenclature, mentions such a substance (XXXVI, 48): "Among the multitude of stones there is tophus. It is unsuitable for [Pg 234]buildings, because it is perishable and soft. Still, however, there are some places which have no other, as Carthage, in Africa. It is eaten away by the emanations from the sea, crumbled to dust by the wind, and washed away by the rain." In fact, tophus was a wide genus among the older mineralogists, Wallerius (Meditationes Physico-Chemicae De Origine Mundi, Stockholm, 1776, p. 186), for instance, gives 22 varieties. For the purposes for which it is used we believe it was always limestone of some form.

[14] Saxum fissile album. (The Interpretatio gives the German as schifer). Agricola mentions it in Bermannus (459), in De Natura Fossilium (p. 319), but nothing definite can be derived from these references. It appears to us from its use to have been either a quartzite or a fissile limestone.

[15] Argol (Feces vini siccae,—"Dried lees of wine." Germ. trans. gives die wein heffen, although the usual German term of the period was weinstein). The lees of wine were the crude tartar or argols of commerce and modern assayers. The argols of white wine are white, while they are red from red wine. The white argol which Agricola so often specifies would have no special excellence, unless it may be that it is less easily adulterated. Agricola (De Nat. Fos., p. 344) uses the expression "Fex vini sicca called tartarum"—one of the earliest appearances of the latter term in this connection. The use of argol is very old, for Dioscorides (1st Century A.D.) not only describes argol, but also its reduction to impure potash. He says (V, 90): "The lees (tryx) are to be selected from old Italian wine; if not, from other similar wine. Lees of vinegar are much stronger. They are carefully dried and then burnt. There are some who burn them in a new earthen pot on a large fire until they are thoroughly incinerated. Others place a quantity of the lees on live coals and pursue the same method. The test as to whether it is completely burned, is that it becomes white or blue, and seems to burn the tongue when touched. The method of burning lees of vinegar is the same.... It should be used fresh, as it quickly grows stale; it should be placed in a vessel in a secluded place." Pliny (XXIII, 31) says: "Following these, come the lees of these various liquids. The lees of wine (vini faecibus) are so powerful as to be fatal to persons on descending into the vats. The test for this is to let down a lamp, which, if extinguished, indicates the peril.... Their virtues are greatly increased by the action of fire." Matthioli, commenting on this passage from Dioscorides in 1565, makes the following remark (p. 1375): "The precipitate of the wine which settles in the casks of the winery forms stone-like crusts, and is called by the works-people by the name tartarum." It will be seen above that these lees were rendered stronger by the action of fire, in which case the tartar was reduced to potassium carbonate. The weinstein of the old German metallurgists was often the material lixiviated from the incinerated tartar.

Dried lees of vinegar (siccae feces aceti; Interpretatio, die heffe des essigs). This would also be crude tartar. Pliny (XXIII, 32) says: "The lees of vinegar (faex aceti); owing to the more acrid material are more aggravating in their effects.... When combined with melanthium it heals the bites of dogs and crocodiles."

[16] Dried lees of aqua which separates gold and silver. (Siccae feces aquarum quae aurum ab argento secernunt. German translation, Der scheidwasser heffe). There is no pointed description in Agricola's works, or in any other that we can find, as to what this material was. The "separating aqua" was undoubtedly nitric acid (see p. [439], Book X). There [Pg 235]are two precipitates possible, both referred to as feces,—the first, a precipitate of silver chloride from clarifying the aqua valens, and the second, the residues left in making the acid by distillation. It is difficult to believe that silver chloride was the feces referred to in the text, because such a precipitate would be obviously misleading when used as a flux through the addition of silver to the assays, too expensive, and of no merit for this purpose. Therefore one is driven to the conclusion that the feces must have been the residues left in the retorts when nitric acid was prepared. It would have been more in keeping with his usual mode of expression, however, to have referred to this material as a residuus. The materials used for making acid varied greatly, so there is no telling what such a feces contained. A list of possibilities is given in [note 8, p. 443]. In the main, the residue would be undigested vitriol, alum, saltpetre, salt, etc., together with potassium, iron, and alum sulphates. The Probierbüchlin (p. 27) also gives this re-agent under the term Toden kopff das ist schlam oder feces auss dem scheydwasser.

[17] Recrementum vitri. (Interpretatio, Glassgallen). Formerly, when more impure materials were employed than nowadays, the surface of the mass in the first melting of glass materials was covered with salts, mostly potassium and sodium sulphates and chlorides which escaped perfect vitrification. This "slag" or "glassgallen" of Agricola was also termed sandiver.

[18] The whole of this expression is "candidus, candido." It is by no means certain that this is tin, for usually tin is given as plumbum candidum.

[Pg 236][19] Sal artificiosus. These are a sort of stock fluxes. Such mixtures are common in all old assay books, from the Probierbüchlin to later than John Cramer in 1737 (whose Latin lectures on Assaying were published in English under the title of "Elements of the Art of Assaying Metals," London, 1741). Cramer observes (p. 51) that: "Artificers compose a great many fluxes with the above-mentioned salts and with the reductive ones; nay, some use as many different fluxes as there are different ores and metals; all which, however, we think needless to describe. It is better to have explained a few of the simpler ones, which serve for all the others, and are very easily prepared, than to tire the reader with confused compositions: and this chiefly because unskilled artificers sometimes attempt to obtain with many ingredients of the same nature heaped up beyond measure, and with much labour, though not more properly and more securely, what might have been easily effected, with one only and the same ingredient, thus increasing the number, not at all the virtue of the things employed. Nevertheless, if anyone loves variety, he may, according to the proportions and cautions above prescribed, at his will chuse among the simpler kinds such as will best suit his purpose, and compose a variety of fluxes with them."

[20] This operation apparently results in a coating to prevent the deflagration of the saltpetre—in fact, it might be permitted to translate inflammatur "deflagrate," instead of kindle.

[21] The results which would follow from the use of these "fluxes" would obviously depend upon the ore treated. They can all conceivably be successful. Of these, the first is the lead-glass of the German assayers—a flux much emphasized by all old authorities, [Pg 237]including Lohneys, Ercker and Cramner, and used even yet. The "powerful flux" would be a reducing, desulphurizing, and an acid flux. The "more powerful" would be a basic flux in which the reducing action of the argols would be largely neutralised by the nitre. The "still more powerful" would be a strongly sulphurizing basic flux, while the "most powerful" would be a still more sulphurizing flux, but it is badly mixed as to its oxidation and basic properties. (See also [note 19] on sal artificiosus).

[22] Lead ash (Cinis Plumbi. Glossary, Pleyasch).—This was obviously, from the method of making, an artificial lead sulphide.

[23] Ashes of lead (Nigri plumbi cinis). This, as well as lead ash, was also an artificial lead sulphide. Such substances were highly valued by the Ancients for medicinal purposes. Dioscorides (V, 56) says: "Burned lead (Molybdos cecaumenos) is made in this way: Sprinkle sulphur over some very thinnest lead plates and put them into a new earthen pot, add other layers, putting sulphur between each layer until the pot is full; set it alight and stir the melted lead with an iron rod until it is entirely reduced to ashes and until none of the lead remains unburned. Then take it off, first stopping up your nose, because the fumes of burnt lead are very injurious. Or burn the lead filings in a pot with sulphur as aforesaid." Pliny (XXXIV., 50) gives much the same directions.

[Pg 238][24] Camphor (camphora). This was no doubt the well-known gum. Agricola, however, believed that camphor (De Nat. Fossilium, p. 224) was a species of bitumen, and he devotes considerable trouble to the refutation of the statements by the Arabic authors that it was a gum. In any event, it would be a useful reducing agent.

[25] Inasmuch as orpiment and realgar are both arsenical sulphides, the use of iron "slag," if it contains enough iron, would certainly matte the sulphur and arsenic. Sulphur and arsenic are the "juices" referred to (see [note 4, p. 1]). It is difficult to see the object of preserving the antimony with such a sulphurizing "addition," unless it was desired to secure a regulus of antimony alone from a given antimonial ore.

[Pg 239][26] The lead free from silver, called villacense, was probably from Bleyberg, not far from Villach in Upper Austria, this locality having been for centuries celebrated for its pure lead. These mines were worked prior to, and long after, Agricola's time.

[Pg 242][27] This method of proportionate weights for assay charges is simpler than the modern English "assay ton," both because of the use of 100 units in the standard of weight (the centumpondium), and because of the lack of complication between the Avoirdupois and Troy scales. For instance, an ore containing a libra of silver to the centumpondium would contain 1/100th part, and the same ratio would obtain, no matter what the actual weight of a centumpondium of the "lesser weight" might be. To follow the matter still further, an uncia being 1/1,200 of a centumpondium, if the ore ran one "uncia of the lesser weight" to the "centumpondium of the lesser weight," it would also run one actual uncia to the actual centumpondium; it being a matter of indifference what might be the actual weight of the centumpondium upon which the scale of lesser weights is based. In fact Agricola's statement (p. [261]) indicates that it weighed an actual drachma. We have, in some places, interpolated the expressions "lesser" and "greater" weights for clarity.

This is not the first mention of this scheme of lesser weights, as it appears in the Probierbüchlein (1500? see [Appendix B]) and Biringuccio (1540). For a more complete discussion of weights and measures see [Appendix C]. For convenience, we repeat here the Roman scale, although, as will be seen in the Appendix, Agricola used the Latin terms in many places merely as nomenclature equivalents of the old German scale.

				Troy Grains.			Ozs.	dwts.	gr.
							per short ton.
1	Siliqua			2.87	Per	Centumpondium	0	3	9
6	Siliquae	=	1 Scripulum	17.2	"	"	1	0	6
4	Scripula	=	1 Sextula	68.7	"	"	4	1	0
6	Sextulae	=	1 Uncia	412.2	"	"	24	6	2
12	Unciae	=	1 Libra	4946.4	"	"	291	13	8
100	Librae	=	1 Centumpondium	494640.0

	However Agricola may occasionally use
16	Unciae	=	1 Libra	6592.0	(?)
100	Librae	=	1 Centumpondium	659200.0	(?)

	Also
							Ozs.	dwts.	gr.
							per short ton.
1	Scripulum			17.2	Per	Centumpondium	1	0	6
3	Scripula	=	1 Drachma	51.5	"	"	3	0	19
2	Drachmae	=	1 Sicilicus	103.0	"	"	6	1	15
4	Sicilici	=	1 Uncia	412.2	"	"	24	6	12
8	Unciae	=	1 Bes	3297.6	"	"	194	12	0

[Pg 243][28] The amalgamation of gold ores is fully discussed in [note 12, p. 297].

[Pg 244][29] For discussion of the silver ores, see [note 8, p. 108]. Rudis silver was a fairly pure silver mineral, the various coloured silvers were partly horn-silver and partly alteration products.

[Pg 245][30] It is difficult to see why copper scales (squamae aeris—copper oxide?) are added, unless it be to collect a small ratio of copper in the ore. This additional copper is not mentioned again, however. The whole of this statement is very confused.

[Pg 247][31] This old story runs that Hiero, King of Syracuse, asked Archimedes to tell him whether a crown made for him was pure gold or whether it contained some proportion of silver. Archimedes is said to have puzzled over it until he noticed the increase in water-level upon entering his bath. Whereupon he determined the matter by immersing bars of pure gold and pure silver, and thus determining the relative specific weights. The best [Pg 248]ancient account of this affair is to be found in Vitruvius, IX, Preface. The story does not seem very probable, seeing that Theophrastus, who died the year Archimedes was born, described the touchstone in detail, and that it was of common knowledge among the Greeks before (see [note 37]). In any event, there is not sufficient evidence in this story on which to build the conclusion of Meyer (Hist. of Chemistry, p. 14) and others, that, inasmuch as Archimedes was unable to solve the problem until his discovery of specific weights, therefore the Ancients could not part gold and silver. The probability that he did not want to injure the King's jewellery would show sufficient reason for his not parting these metals. It seems probable that the Ancients did part gold and silver by cementation. (See note on p. [458]).

[32] The Alchemists (with whose works Agricola was familiar—vide [preface]) were the inventors of nitric acid separation. (See note on p. [460]).

[33] Parting gold and silver by nitric acid is more exhaustively discussed in [Book X.] and [note 10, p. 443].

[34] The lesser weights, probably.

[Pg 251][35] Lead and Tin seem badly mixed in this paragraph.

[36] It is not clear what is added.

[Pg 252][37] Historical Note on Touchstone. (Coticula. Interpretatio,—Goldstein). Theophrastus is, we believe, the first to describe the touchstone, although it was generally known to the Greeks, as is evidenced by the metaphors of many of the poets,—Pindar, Theognis, Euripides, etc. The general knowledge of the constituents of alloys which is implied, raises the question as to whether the Greeks did not know a great deal more about parting metals, than has been attributed to them. Theophrastus says (78-80): "The nature of the stone which tries gold is also very wonderful, as it seems to have the same power with fire; which is also a test of that metal. Some people have for this reason questioned the truth of this power in the stone, but their doubts are ill-founded, for this trial is not of the same nature or made in the same manner as the other. The trial by fire is by the colour and by the quantity lost by it; but that by the stone is made only by rubbing the metal on it; the stone seeming to have the power to receive separately the distinct particles of different metals. It is said also that there is a much better kind of this stone now found out, than that which was formerly used; insomuch that it now serves not only for the trial of refined gold, but also of copper or silver coloured with gold; and shows how much of the adulterating matter by weight is mixed with gold; this has signs which it yields from the smallest weight of the adulterating matter, which is a grain, from thence a colybus, and thence a quadrans or semi-obolus, by which it is easy to distinguish if, and in what degree, that metal is adulterated. All these stones are found in the River Tmolus; their texture is smooth and like that of pebbles; their figure broad, not round; and their bigness twice that of the common larger sort of pebbles. In their use in the trial of metals there is a difference in power between their upper surface, which has lain toward the sun, and their under, which has been to the earth; the upper performing its office the more nicely; and this is consonant to reason, as the upper part is dryer; for the humidity of the other surface hinders its receiving so well the particles of metals; for the same reason also it does not perform its office as well in hot weather as in colder, for in the hot it emits a kind of humidity out of its substance, which runs all over it. This hinders the metalline particles from adhering perfectly, and makes mistakes in the trials. This exudation of a humid matter is also common to many other stones, among others, to those of which statues are made; and this has been looked on as peculiar to the statue." (Based on [Pg 253]Hill's trans.) This humid "exudation of fine-grained stones in summer" would not sound abnormal if it were called condensation. Pliny (XXXIII, 43) says: "The mention of gold and silver should be accompanied by that of the stone called coticula. Formerly, according to Theophrastus, it was only to be found in the river Tmolus but now found in many parts, it was found in small pieces never over four inches long by two broad. That side which lay toward the sun is better than that toward the ground. Those experienced with the coticula when they rub ore (vena) with it, can at once say how much gold it contains, how much silver or copper. This method is so accurate that they do not mistake it to a scruple." This purported use for determining values of ore is of about Pliny's average accuracy. The first detailed account of touch-needles and their manner of making, which we have been able to find, is that of the Probierbüchlein (1527? see [Appendix]) where many of the tables given by Agricola may be found.

[38] De Natura Fossilium (p. 267) and De Ortu et Causis Subterraneorum (p. 59). The author does not add any material mineralogical information to the quotations from Theophrastus and Pliny given above.

[39] In these tables Agricola has simply adopted Roman names as equivalents of the old German weights, but as they did not always approximate in proportions, he coined terms such as "units of 4 siliquae," etc. It might seem more desirable to have introduced the German terms into this text, but while it would apply in this instance, as we have discussed on p. [259], the actual values of the Roman weights are very different from the German, and as elsewhere in the book actual Roman weights are applied, we have considered it better to use the Latin terms consistently throughout. Further, the obsolete German would be to most readers but little improvement upon the Latin. For convenience of readers we set out the various scales as used by Agricola, together with the German:—

Roman Scale.				Old German Scale.
6	Siliquae	=	1 Scripulum	3	Grenlin	=	1 Gran
4	Scripula	=	1 Sextula	4	Gran	=	1 Krat
2	Sextulae	=	1 Duella	24	Kratt	=	1 Mark
24	Duellae	=	1 Bes		or
				24	Grenlin	=	1 "Nummus"
				12	"Nummi"	=	1 Mark

Also the following scales are applied to fineness by Agricola:—
3	Scripula	=	1 Drachma	4	Pfennige	=	1 Quintlein
2	Drachmae	=	1 Sicilicus	4	Quintlein	=	1 Loth
2	Sicilici	=	1 Semuncia	16	Loth	=	1 Mark
16	Semunciae	=	1 Bes

The term "nummus," a coin, given above and in the text, appears in the German translation as pfennig as applied to both German scales, but as they are of different values, [Pg 254]we have left Agricola's adaptation in one scale to avoid confusion. The Latin terms adopted by Agricola are given below, together with the German:—

Roman Term.	German Term.	Number in one Mark or Bes.	Value in Siliquae.
Siliqua		1152	1
"Unit of 4 Siliquae"	Grenlin	288	4
	Pfennig	256	—
Scripulum	Scruple (?)	192	6
Semi-sextula	Gran	96	12
Drachma	Quintlein	64	18
Sextula	Halb Krat	48	24
Sicilicus	Halb Loth	32	36
Duella	Krat	24	48
Semuncia	Loth	16	72
"Unit of 5 Drachmae & 1 Scripulum"	"Nummus"	12	96
Uncia	Untzen	8	144
Bes	Mark	1	1152

While the proportions in a bes or mark are the same in both scales, the actual weight values are vastly different—for instance, the mark contained about 3609.6, and the bes 3297 Troy Grains. Agricola also uses:

Selibra	Halb-pfundt
Libra	Pfundt
Centumpondium	Centner.

As the Roman libra contains 12 unciae and the German pfundt 16 untzen, the actual weights of these latter quantities are still further apart—the former 4946 and the latter 7219 Troy grains.

[40] There are no tables in the Latin text, the whole having been written out in extenso, but they have now been arranged as above, as being in a much more convenient and expressive form.

[Pg 259][41] See [note 39 above].

[Pg 261][42] See [note 27, p. 242], for discussion of this "Assay ton" arrangement.

[Pg 263][43] Agrippinenses and Antuerpiani.

BOOK VIII.

uestions of assaying were explained in the last Book, and I have now come to a greater task, that is, to the description of how we extract the metals. First of all I will explain the method of preparing the ore [1]; for since Nature usually creates metals in an impure state, mixed with earth, stones, and solidified juices, it is necessary to separate most of these impurities from the ores as far as can be, before they are smelted, and therefore I will now describe the methods by which the ores are sorted, broken with hammers, burnt, crushed with stamps, ground into powder, sifted, washed, roasted, and calcined [2].

I will start at the beginning with the first sort of work. Experienced miners, when they dig the ore, sort the metalliferous material from earth, stones, and solidified juices before it is taken from the shafts and tunnels, and they put the valuable metal in trays and the waste into buckets. But if some miner who is inexperienced in mining matters has omitted to do this, or even if some experienced miner, compelled by some unavoidable necessity, has been unable to do so, as soon as the material which has been dug out has been removed from the mine, all of it should be examined, and that part of the ore which is rich in metal sorted from that part of it which is devoid of metal, whether such part be earth, or solidified juices, or stones. To smelt waste together with an ore involves a loss, for some expenditure is thrown away, seeing that out of earth and stones only empty and useless slags are melted out, and further, the solidified juices also impede the smelting of the metals and cause loss. The rock which lies contiguous to rich ore should also be broken into small pieces, crushed, and washed, lest any of the mineral should be lost. When, either through ignorance or carelessness, the miners while excavating have mixed the ore with earth or broken rock, the work of sorting the crude metal or the best ore is done not only by men, but also by boys and women.

Ore is burned for two reasons; either that from being hard, it may become soft and more easily broken and more readily crushed with a hammer or stamps, and then can be smelted; or that the fatty things, that is to say, sulphur, bitumen, orpiment, or realgar [3] may be consumed. Sulphur is frequently found in metallic ores, and, generally speaking, is more harmful to the metals, except gold, than are the other things. It is most harmful of all to iron, and less to tin than to bismuth, lead, silver, or copper. Since very rarely gold is found in which there is not some silver, even gold ores containing sulphur ought to be roasted before they are smelted, because, in a very vigorous furnace fire, sulphur resolves metal into ashes and makes slag of it. Bitumen acts in the same way, in fact sometimes it consumes silver, which we may see in bituminous cadmia[4].

Some use a sieve made of copper, having square copper handles on both sides, and through these handles runs a pole, of which one end projects three-quarters of a foot beyond one handle; the workman then places that end in a rope which is suspended from a beam, and rapidly shakes the pole alternately backward and forward. By this movement the small particles fall through the bottom of the sieve. In order that the end of the pole may be easily placed in the rope, a stick, two palms long, holds open the lower part of the rope as it hangs double, each end of the rope being tied to the beam; part of the rope, however, hangs beyond the stick to a length of half a foot.

The third mill is turned round and round, and not pushed by hand; but between this and the others there is a great distinction, for the lower millstone is so shaped at the top that it can hold within it the upper millstone, which revolves around an iron axle; this axle is fastened in the centre of the lower stone and passes through the upper stone. A workman, by grasping in his hand an upright iron bar placed in the upper millstone, moves it round. The middle of the upper millstone is bored through, and the ore, being thrown into this opening, falls down upon the lower millstone and is there ground to powder, which gradually runs out through its opening; it is washed by various methods before it is mixed with quicksilver, which I will explain presently.

Seven methods of washing are in common use for the ores of many metals; for they are washed either in a simple buddle, or in a divided buddle, or in an ordinary strake, or in a large tank, or in a short strake, or in a canvas strake, or in a jigging sieve. Other methods of washing are either peculiar to some particular metal, or are combined with the method of crushing wet ore by stamps.

Pulverized ore is washed in the head of this kind of a buddle; but usually when tin-stone is washed in it, interlacing fir boughs are put into the buddle, in the same manner as in the sluice when wet ore is crushed with stamps. The larger tin-stone particles, which sink in the upper part of the buddle, are washed separately in a strake; those particles which are of medium size, and settle in the middle part, are washed separately in the same way; and the mud mixed with minute particles of tin-stone, which has settled in the lowest part of the buddle below the fir boughs, is washed separately on the canvas strakes.

This method of washing was first devised by the miners who treated tin ore, whence it passed on from the works of the tin workers to those of the silver workers and others; this system is even more reliable than washing in jigging-sieves. Near this ordinary strake there is generally a canvas strake.

I have explained the methods of washing which are used in common for the ores of many metals. I now come to another method of crushing ore, for I ought to speak of this before describing those methods of washing which are peculiar to ores of particular metals.

This method of washing has lately undergone a considerable change; for the launder which carries the water, mixed with the crushed tin-stone and fine sand which flow from the openings of the screen, does not reach to a transverse trough which is inside the same room, but runs straight through a partition into a small settling-pit. A boy draws a three-toothed rake through the material which has settled in the portion of the launder outside the room, by which means the larger sized particles of tin-stone settle at the bottom, and these the washer takes out with the wooden shovel and carries into the room; this material is thrown into an ordinary strake and swept with a wooden scrubber and washed. As for those tin-stone particles which the water carries off from the strake, after they have been brought back on to the strake, he washes them again until they are clean.

Below all buddles or strakes, both inside and outside the building, there are placed either settling-pits or cross-troughs into which they discharge, in order that the water may carry on down into the stream but very few of the most minute particles of tin-stone. The large settling-pit which is outside the building is generally made of joined flooring, and is eight feet in length, breadth and depth. When a large quantity of mud, mixed with very fine tin-stone, has settled in it, first of all the water is let out by withdrawing a plug, then the mud which is taken out is washed outside the house on the canvas strakes, and afterward the concentrates are washed on the strake which is inside the building. By these methods the very finest tin-stone is made clean.

In some parts of Moravia, gold ore, which consists of quartz mixed with gold, is placed under the stamps and crushed wet. When crushed fine it flows out through a launder into a trough, is there stirred by a wooden scrubber, and the minute particles of gold which settle in the upper end of the trough are washed in a black bowl.

So far I have spoken of machines which crush wet ore with iron-shod stamps. I will now explain the methods of washing which are in a measure peculiar to the ore of certain metals, beginning with gold. The ore which contains particles of this metal, and the sand of streams and rivers which contains grains of it, are washed in frames or bowls; the sands especially are also washed in troughs. More than one method is employed for washing on frames, for these frames either pass or retain the particles or concentrates of gold; they pass them if they have holes, and retain them if they have no holes. But either the frame itself has holes, or a box is substituted for it; if the frame itself is perforated it passes the particles or concentrates of gold into a trough; if the box has them, it passes the gold material into the long sluice.

The gold particles are also caught on frames which are either bare or covered. If bare, the particles are caught in pockets; if covered, they cling to the coverings. Pockets are made in various ways, either with iron wire or small cross-boards fixed to the frame, or by holes which are sunk into the sluice itself or into its head, but which do not quite go through. These holes are round or square, or are grooves running crosswise. The frames are either covered with skins, pieces of cloth, or turf, which I will deal with one by one in turn.

The metalliferous material is sometimes found not very deep beneath the surface of the earth, but sometimes so deep that it is necessary to drive tunnels and sink shafts. It is transported to the washing-box in wheelbarrows, and when the washers are about to begin they lay a small launder, through which there flows on to the iron plate so much water as is necessary for this washing. Next, a boy throws the metalliferous material on to the iron plate with an iron shovel and breaks the small lumps, stirring them this way and that with the same implement. Then the water and sand penetrating the holes of the plate, fall into the box, while all the coarse gravel remains on the plate, and this he throws into a wheelbarrow with the same shovel. Meantime, a younger boy continually stirs the sand under the plate with a wooden scrubber nearly as wide as the box, and drives it to the upper end of the box; the lighter material, as well as a small amount of tin-stone, is carried by the water down into the underlying trough. The boys carry on this labour without intermission until they have filled four wheelbarrows with the coarse and worthless residues, which they carry off and throw away, or three wheelbarrows if the material is rich in black tin. Then the foreman has the plank removed which was in front of the iron plate, and on which the boy stood. The sand, mixed with the tin-stone, is frequently pushed backward and forward with a scrubber, and the same sand, because it is lighter, takes the upper place, and is removed as soon as it appears; that which takes the lower place is turned over with a spade, in order that any that is light can flow away; when all the tin-stone is heaped together, he shovels it out of the box and carries it away. While the foreman does this, one boy with an iron hoe stirs the sand mixed with fine tin-stone, which has run out of the box and has settled in the trough and pushes it back to the uppermost part of the trough, and this material, since it contains a very great amount of tin-stone, is thrown on to the plate and washed again. The material which has settled in the lowest part of the trough is taken out separately and piled in a heap, and is washed on the ordinary strake; that which has settled in the pool is washed on the canvas strake. In the summer-time this fruitful labour is repeated more often, in fact ten or eleven times. The tin-stone which the foreman removes from the box, is afterward washed in a jigging sieve, and lastly in a tub, where at length all the sand is separated out. Finally, any material in which are mixed particles of other metals, can be washed by all these methods, whether it has been disintegrated from veins or stringers, or whether it originated from venae dilatatae, or from streams and rivers.

The burned tin-stone should then be washed again on the strake, for in this way the material which has been run together is carried away by the water into the cross-trough, where it is gathered up and worked over, and again washed on the strake. By this method the metal is separated from that which is devoid of metal.

END OF BOOK VIII.