FOOTNOTES:
[Pg 546][1] The history of salt-making in salt-pans, from sea-water or salt springs, goes further back than human records. From an historical point of view the real interest attached to salt lies in the bearing which localities rich in either natural salt or salt springs, have had upon the movements of the human race. Many ancient trade routes have been due to them, and innumerable battles have been fought for their possession. Salt has at times served for currency, and during many centuries in nearly every country has served as a basis of taxation. These subjects do not, however, come within the scope of this text. For the quotation from Pliny referred to, see [Note 14 below], on bitumen.
[2] The first edition gives graviorem, the latter editions gratiorem, which latter would have quite the reverse meaning from the above.
[Pg 550][3] The following are approximately the English equivalents:—
| Pints. | Quarts. | Gallons. | |||||
| 1 | Cyathus | .08 | |||||
| 3 | Cyathi | = | 1 | Quartarius | .24 | ||
| 4 | Quartarii | = | 1 | Sextarius | .99 | ||
| 6 | Sextarii | = | 1 | Congius | 5.94 | 2.97 | |
| 16 | Sextarii | = | 1 | Modius | 15.85 | 7.93 | 1.98 |
| 8 | Congii | = | 1 | Amphora | 47.57 | 23.78 | 5.94 |
The dipper mentioned would thus hold about one and one quarter gallons, and the cask ten gallons.
[Pg 552][4] The salt industry, founded upon salt springs, is still of importance to this city. It was a salt centre of importance to the Germanic tribes before Charles, the son of Charlemagne, erected a fortress here in 806. Mention of the salt works is made in the charter by Otto I., conveying the place to the Diocese of Magdeburg, in 968.
[Pg 558][5] Pliny XXXI., 39-40. "In the Gallic provinces in Germany they pour salt water upon burning wood. The Spaniards in a certain place draw the brine from wells, which they call Muria. They indeed think that the wood turns to salt, and that the oak is the best, being the kind which is itself salty. Elsewhere the hazel is praised. Thus the charcoal even is turned into salt when it is steeped in brine. Whenever salt is made with wood it is black."
[6] We have elsewhere in this book used the word "soda" for the Latin term nitrum, because we believe as used by Agricola it was always soda, and because some confusion of this term with its modern adaptation for saltpetre (nitre) might arise in the mind of the reader. Fortunately, Agricola usually carefully mentions other alkalis, such as the product from lixiviation of ashes, separately from his nitrum. In these paragraphs, however, he has soda and potash hopelessly mixed, wherefore we have here introduced the Latin term. The actual difference between potash and soda—the nitrum of the Ancients, and the alkali of Geber (and the glossary of Agricola), was not understood for two hundred years after Agricola, when Duhamel made his well-known determinations; and the isolation of sodium and potassium was, of course, still later by fifty years. If the reeds and rushes described in this paragraph grew near the sea, the salt from lixiviation would be soda, and likewise the Egyptian product was soda, but the lixiviation of wood-ash produces only potash; as seen above, all are termed nitrum except the first.
Historical Notes.—The word nitrum, nitron, nitri, neter, nether, or similar forms, occurs in innumerable ancient writings. Among such references are Jeremiah (II., 22) Proverbs (XXV., 20), Herodotus (II., 86, 87), Aristotle (Prob. I., 39, De Mirab. 54), Theophrastus (De Igne 435 ed. Heinsii, Hist. Plants III., 9), Dioscorides (V., 89), Pliny (XIV., 26, and XXXI., 46). A review of disputations on what salts this term comprised among the Ancients would itself fill a volume, but from the properties named it was no doubt mostly soda, more rarely potash, and sometimes both mixed with common salt. There is every reason to believe from the properties and uses mentioned, that it did not generally comprise nitre (saltpetre)—into which superficial error the nomenclature has led many translators. The preparation by way of burning, and the use of nitrum for purposes for which we now use soap, for making glass, for medicines, cosmetics, salves, painting, in baking powder, for preserving food, embalming, etc., and the descriptions of its taste in "nitrous" waters,—all answer for soda and potash, but not for saltpetre. It is possible that the common occurrence of saltpetre as an efflorescence on walls might naturally lead to its use, but in any event its distinguishing characteristics are nowhere mentioned. As sal-ammoniac occurred [Pg 559]in the volcanoes in Italy, it also may have been included in the nitrum mentioned. Nitrum was in the main exported from Egypt, but Theophrastus mentions its production from wood-ash, and Pliny very rightly states that burned lees of wine (argol) had the nature of nitrum. Many of the ancient writers understood that it was rendered more caustic by burning, and still more so by treatment with lime. According to Beckmann (Hist. of Inventions II., p. 488), the form of the word natron was first introduced into Europe by two travellers in Egypt, Peter Ballon and Prosper Alpinus, about 1550. The word was introduced into mineralogy by Linnaeus in 1736. In the first instance natron was applied to [Pg 560]soda and potash in distinction to nitre for saltpetre, and later natron was applied solely to soda.
It is desirable to mention here two other forms of soda and potash which are frequently mentioned by Agricola. "Ashes which wool dyers use" (cineres quo infectores lanarum utuntur).—There is no indication in any of Agricola's works as to whether this was some special wood-ash or whether it was the calcined residues from wool washing. The "yolk" or "suint" of wool, originating from the perspiration of the animal, has long been a source of crude potash. The water, after washing the wool, is evaporated, and the residue calcined. It contains about 85% K2CO3, the remainder being sodium and potassium sulphates. Another reason for assuming that it was not a wood-ash product, is that these products are separately mentioned. In either event, whether obtained from wool residues or from lixiviation of wood-ash, it would be an impure potash. In some methods of wool dyeing, a wash of soda was first given, so that it is barely possible that this substance was sodium carbonate.
"Salt made from the ashes of musk ivy" (sal ex anthyllidis cinere factus,—Glossary, salalkali). This would be largely potash.
[7] This wondrous illustration of soda-making from Nile water is no doubt founded upon Pliny (XXXI., 46). "It is made in almost the same manner as salt, except that sea-water is put into salt pans, whereas in the nitrous pans it is water of the Nile; these, with the subsidence of the Nile during the forty days, are impregnated with nitrum."
[8] This paragraph displays hopeless ignorance. Borax was known to Agricola and greatly used in his time; it certainly was not made from these compounds, but was imported from Central Asia. Sal-ammoniac was also known in his time, and was used like borax as a soldering agent. The reaction given by Agricola would yield free ammonia. The following historical notes on borax and sal-ammoniac may be of service.
Borax.—The uncertainties of the ancient distinctions in salts involve borax deeply. The word Baurach occurs in Geber and the other early Alchemistic writings, but there is nothing to prove that it was modern borax. There cannot be the slightest doubt, however, that the material referred to by Agricola as borax was our borax, because of the characteristic qualities incidentally mentioned in [Book VII]. That he believed it was an artificial product from nitrum is evident enough from his usual expression "chrysocolla made from nitrum, which the Moors call borax." Agricola, in De Natura Fossilium (p. 206-7), makes the following statements, which could leave no doubt on the subject:—"Native nitrum is found in the earth or on the surface.... It is from this variety that the Venetians make chrysocolla, which I call borax.... The second variety of artificial nitrum is made at the present day from the native nitrum, called by the Arabs tincar, but I call it usually by the Greek name chrysocolla; it is really the Arabic borax.... This nitrum does not decrepitate nor fly out of the fire; however, the native variety swells up from within." The application of the word chrysocolla (chrysos, gold; colla, solder) to soldering materials, and at the same time to the copper mineral, is of Greek origin. If any further proof were needed as to the substance meant by Agricola, it lies in the word tincar. For a long time the borax of Europe was imported from Central Asia, through Constantinople and Venice, under the name of tincal or tincar. When this trade began, we do not know; evidently before Agricola's time. The statement here of making borax from alum and sal-ammoniac is identical with the assertion of Biringuccio (II., 9).
Sal-ammoniac.—The early history of this—ammonium chloride—is also under a cloud. Pliny (XXXI., 39) speaks of a sal-hammoniacum, and Dioscorides (V., 85) uses much the same word. Pliny describes it as from near the temple of Ammon in Egypt. None of the distinctive characteristics of sal-ammoniac are mentioned, and there is every reason to believe it was either common salt or soda. Herodotus, Strabo, and others mention common salt sent from about the same locality. The first authentic mention is in Geber, who calls it sal-ammoniacum, and describes a method of making, and several characteristic reactions. It was known in the Middle Ages under various names, among them sal-aremonicum. Agricola (De Nat. Fos., III., p. 206) notes its characteristic quality of volatilization. "Sal-ammoniac ... in the fire neither crackles nor flies out, but is totally consumed." He also says (p. 208): "Borax is used by goldsmiths to solder gold, likewise silver. The artificers who make iron needles (tacks?) similarly use sal-ammoniac when they cover the heads with tin." The statement from Pliny mentioned in this paragraph is from XXXIII., 29, where he describes the chrysocolla used as gold solder as made from verdigris, nitrum, and urine in the way quoted. It is quite possible that this solder was sal-ammoniac, though not made in quite this manner. Pliny refers in several places (XXXIII., 26, 27, 28, and 29, XXXV., 28, etc.) to chrysocolla, about which he is greatly confused as between gold-solder, the copper mineral, and a green pigment, the latter being of either mineral origin.
[Pg 561][9] Saltpetre was secured in the Middle Ages in two ways, but mostly from the treatment of calcium nitrate efflorescence on cellar and similar walls, and from so-called saltpetre plantations. In this description of the latter, one of the most essential factors is omitted until the last sentence, i.e., that the nitrous earth was the result of the decay of organic or animal matter over a long period. Such decomposition, in the presence of potassium and calcium carbonates—the lye and lime—form potassium and calcium nitrates, together with some magnesium and sodium nitrates. After lixiviation, the addition of lye converts the calcium and magnesium nitrates into saltpetre, i.e., Ca(NO3)2 + K2CO3 = CaCO3 + 2KNO3. The carbonates precipitate out, leaving the saltpetre in solution, from which it was evaporated and crystallized out. The addition of alum as mentioned would scarcely improve the situation.
The purification by repeated re-solution and addition of lye, and filtration, would eliminate the remaining other salts. The purification with sulphur, however, is more difficult [Pg 562]to understand. In this case the saltpetre is melted and the sulphur added and set alight. Such an addition to saltpetre would no doubt burn brilliantly. The potassium sulphate formed would possibly settle to the bottom, and if the "greasy matter" were simply organic impurities, they might be burned off. This method of refining appears to have been copied from Biringuccio (X., 1), who states it in almost identical terms.
Historical Note.—As mentioned in [Note 6 above], it is quite possible that the Ancients did include efflorescence of walls under nitrum; but, so far as we are aware, no specific mention of such an occurrence of nitrum is given, and, as stated before, there is every reason to believe that all the substances under that term were soda and potash. Especially the frequent mention of the preparation of nitrum by way of burning, argues strongly against saltpetre being included, as they would hardly have failed to notice the decrepitation. Argument has been put forward that Greek fire contained saltpetre, but it amounts to nothing more than argument, for in those receipts preserved, no salt of any kind is mentioned. It is most likely that the leprosy of house-walls of the Mosaic code (Leviticus XIV., 34 to 53) was saltpetre efflorescence. The drastic treatment by way of destruction of such "unclean" walls and houses, however, is sufficient evidence that this salt was not used. The first certain mention of saltpetre (sal petrae) is in Geber. As stated before, the date of this work is uncertain; in any event it was probably as early as the 13th Century. He describes the making of "solvative water" with alum and saltpetre, so there can be no doubt as to the substance (see Note on p. [460], on nitric acid). There is also a work by a nebulous Marcus Graecus, where the word sal petrosum is used. And it appears that Roger Bacon (died 1294) and Albertus Magnus (died 1280) both had access to that work. Bacon uses the term sal petrae frequently enough, and was the first to describe gunpowder (De Mirabili Potestate Artis et Naturae 1242). He gives no mention of the method of making his sal petrae. Agricola uses throughout the Latin text the term halinitrum, a word he appears to have coined himself. However, he gives its German equivalent in the Interpretatio as salpeter. The only previous description of the method of making saltpetre, of which we are aware, is that of Biringuccio (1540), who mentions the boiling of the excrescences from walls, and also says a good deal about boiling solutions from "nitrous" earth, which may or may not be of "plantation" origin. He also gives this same method of refining with sulphur. In any event, this statement by Agricola is the first clear and complete description of the saltpetre "plantations." Saltpetre was in great demand in the Middle Ages for the manufacture of gunpowder, and the first record of that substance and of explosive weapons necessarily involves the knowledge of saltpetre. However, authentic mention of such weapons only begins early in the 14th Century. Among the earliest is an authority to the Council of Twelve at Florence to appoint persons to make cannon, etc., (1326), references to cannon in the stores of the Tower of London, 1388, &c.
[Pg 564][10] There are three methods of manufacturing alum described by Agricola, the first and third apparently from shales, and the second from alum rock or "alunite." The reasons for assuming that the first process was from shales, are the reference to the "aluminous earth" as ore (venae) coming from "veins," and also the mixture of vitriol. In this process the free sulphuric acid formed by the oxidation of pyrites reacts upon the argillaceous material to form aluminium sulphate. The decomposed ore is then placed in tanks and lixiviated. The solution would contain aluminium sulphate, vitriol, and other impurities. By the addition of urine, the aluminium sulphate would be converted into ammonia alum. Agricola is, of course, mistaken as to the effect of the addition, being under the belief that it separated the vitriol from the alum; in fact, this belief was general until the latter part of the 18th Century, when Lavoisier determined that alum must have an alkali base. Nor is it clear [Pg 565]from this description exactly how they were separated. In a condensed solution allowed to cool, the alum would precipitate out as "alum meal," and the vitriol would "float on top"—in solution. The reference to "meal" may represent this phenomenon, and the re-boiling referred to would be the normal method of purification by crystallization. The "asbestos" and gypsum deposited in the caldrons were no doubt feathery and mealy calcium sulphate. The alum produced would, in any event, be mostly ammonia alum.
The second process is certainly the manufacture from "alum rock" or "alunite" (the hydrous sulphate of aluminium and potassium), such as that mined at La Tolfa in the Papal States, where the process has been for centuries identical with that here described. The alum there produced is the double basic potassium alum, and crystallizes into cubes instead of octahedra, i.e., the Roman alum of commerce. The presence of much ferric oxide gives the rose colour referred to by Agricola. This account is almost identical with that of Biringuccio (II., 4), and it appears from similarity of details that Agricola, as stated in his [preface], must have "refreshed his mind" from this description; it would also appear from the [preface] that he had himself visited the locality.
The third process is essentially the same as the first, except that the decomposition of the pyrites was hastened by roasting. The following obscure statement of some interest occurs in Agricola's De Natura Fossilium, p. 209:—"... alum is made from vitriol, for when oil is made from the latter, alum is distilled out (expirat). This absorbs the clay which is used in cementing glass, and when the operation is complete the clay is macerated with pure water, and the alum is soon afterward deposited in the shape of small cubes." Assuming the oil of vitriol to be sulphuric acid and the clay "used in cementing glass" to be kaolin, we have here the first suggestion of a method for producing alum which came into use long after.
"Burnt alum" (alumen coctum).—Agricola frequently uses this expression, and on p. [568], describes the operation, and the substance is apparently the same as modern dehydrated alum, often referred to as "burnt alum."
Historical Notes.—Whether the Ancients knew of alum in the modern sense is a most vexed question. The Greeks refer to a certain substance as stypteria, and the Romans refer to this same substance as alumen. There can be no question as to their knowledge and common use of vitriol, nor that substances which they believed were entirely different from vitriol were comprised under the above names. Beckmann (Hist. of Inventions, Vol. I., p. 181) seems to have been the founder of the doctrine that the ancient alumen was vitriol, and scores of authorities seem to have adopted his arguments without inquiry, until that belief [Pg 566]is now general. One of the strongest reasons put forward was that alum does not occur native in appreciable quantities. Apart from the fact that the weight of this argument has been lost by the discovery that alum does occur in nature to some extent as an aftermath of volcanic action, and as an efflorescence from argillaceous rocks, we see no reason why the Ancients may not have prepared it artificially. One of the earliest mentions of such a substance is by Herodotus (II., 180) of a thousand talents of stypteria, sent by Amasis from Egypt as a contribution to the rebuilding of the temple of Delphi. Diodorus (V., 1) mentions the abundance which was secured from the Lipari Islands (Stromboli, etc.), and a small quantity from the Isle of Melos. Dioscorides (V., 82) mentions Egypt, Lipari Islands, Melos, Sardinia, Armenia, etc., "and generally in any other places where one finds red ochre (rubrica)." Pliny (XXXV., 52) gives these same localities, and is more explicit as to how it originates—"from an earthy water which exudes from the earth." Of these localities, the Lipari Islands (Stromboli, etc.), and Melos are volcanic enough, and both Lipari and Melos are now known to produce natural alum (Dana. Syst. Min., p. 95; and Tournefort, "Relation d'un voyage du Levant." London, 1717, Lettre IV., Vol. 1.). Further, the hair-like alum of Dioscorides, repeated by Pliny below, was quite conceivably fibrous kalinite, native potash alum, which occurs commonly as an efflorescence. Be the question of native alum as it may—and vitriol is not much more common—our own view that the ancient alumen was alum, is equally based upon the artificial product. Before entering upon the subject, we consider it desirable to set out the properties of the ancient substance, a complete review of which is given by Pliny (XXXV., 52), he obviously quoting also from Dioscorides, which, therefore, we do not need to reproduce. Pliny says:—
"Not less important, or indeed dissimilar, are the uses made of alumen; by which name is understood a sort of salty earth. Of this, there are several kinds. In Cyprus there is a white alumen, and a darker kind. There is not a great difference in their colour, though the uses made of them are very dissimilar,—the white alumen being employed in a liquid state for dyeing wool bright colours, and the dark-coloured alumen, on the other hand, for giving wool a sombre tint. Gold is purified with black alumen. Every kind of alumen is from a limus water which exudes from the earth. The collection of it commences in winter, and it is dried by the summer sun. That portion of it which first matures is the whitest. It is obtained in Spain, Egypt, Armenia, Macedonia, Pontus, Africa, and the islands of Sardinia, Melos, Lipari, and Strongyle; the most esteemed, however, is that of Egypt, the next best from Melos. Of this last there are two kinds, the liquid alumen, and the solid. Liquid alumen, to be good, should be of a limpid and milky appearance; when [Pg 568]rubbed, it should be without roughness, and should give a little heat. This is called phorimon. The mode of detecting whether it has been adulterated is by pomegranate juice, for, if genuine, the mixture turns black. The other, or solid, is pale and rough and turns dark with nut-galls; for which reason it is called paraphoron. Liquid alumen is naturally astringent, indurative, and corrosive; used in combination with honey, it heals ulcerations.... There is one kind of solid alumen, called by the Greeks schistos, which splits into filaments of a whitish colour; for which reason some prefer calling it trichitis (hair like). Alumen is produced from the stone chalcitis, from which copper is also made, being a sort of coagulated scum from that stone. This kind of alumen is less astringent than the others, and is less useful as a check upon bad humours of the body.... The mode of preparing it is to cook it in a pan until it has ceased being a liquid. There is another variety of alumen also, of a less active nature, called strongyle. It is of two kinds. The fungous, which easily dissolves, is utterly condemned. The better kind is the pumice-like kind, full of small holes like a sponge, and is in round pieces, more nearly white in colour, somewhat greasy, free from grit, friable, and does not stain black. This last kind is cooked by itself upon charcoal until it is reduced to pure ashes. The best kind of all is that called melinum, from the Isle of Melos, as I have said, none being more effectual as an astringent, for staining black, and for indurating, and none becomes more dry.... Above all other properties of alumen is its remarkable astringency, whence its Greek name.... It is injected for dysentry and employed as a gargle." The lines omitted refer entirely to medical matters which have no bearing here. The following paragraph (often overlooked) from Pliny (XXXV., 42) also has an important bearing upon the subject:—"In Egypt they employ a wonderful method of dyeing. The white cloth, after it is pressed, is stained in various places, not with dye stuffs, but with substances which absorb colours. These applications are not apparent on the cloth, but when it is immersed in a caldron of hot dye it is removed the next moment brightly coloured. The remarkable circumstance is that although there be only one dye in the caldron yet different colours appear in the cloth."
It is obvious from Pliny's description above, and also from the making of vitriol (see [Note 11, p. 572]), that this substance was obtained from liquor resulting from natural or artificial lixiviation of rocks—in the case of vitriols undoubtedly the result of decomposition of pyritiferous rocks (such as chalcitis). Such liquors are bound to contain aluminum sulphate if there is any earth or clay about, and whether they contained alum would be a question of an alkali being present. If no alkali were present in this liquor, vitriol would [Pg 569]crystallize out first, and subsequent condensation would yield aluminum sulphate. If alkali were present, the alum would crystallize out either before or with the vitriol. Pliny's remark, "that portion of it which first matures is whitest", agrees well enough with this hypothesis. No one will doubt that some of the properties mentioned above belong peculiarly to vitriol, but equally convincing are properties and uses that belong to alum alone. The strongly astringent taste, white colour, and injection for dysentry, are more peculiar to alum than to vitriol. But above all other properties is that displayed in dyeing, for certainly if we read this last quotation from Pliny in conjunction with the statement that white alumen produces bright colours and the dark kind, sombre colours, we have the exact reactions of alum and vitriol when used as mordants. Therefore, our view is that the ancient salt of this character was a more or less impure mixture ranging from alum to vitriol—"the whiter the better." Further, considering the ancient knowledge of soda (nitrum), and the habit of mixing it into almost everything, it does not require much flight of imagination to conceive its admixture to the "water," and the absolute production of alum.
Whatever may have been the confusion between alum and vitriol among the Ancients, it appears that by the time of the works attributed to Geber (12th or 13th Century), the difference was well known. His work (Investigationes perfectiones, IV.) refers to alumen glaciale and alumen jameni as distinguished from vitriol, and gives characteristic reactions which can leave no doubt as to the distinction. We may remark here that the repeated statement apparently arising from Meyer (History of Chemistry, p. 51) that Geber used the term alum de rocca is untrue, this term not appearing in the early Latin translations. During the 15th Century alum did come to be known in Europe as alum de rocca. Various attempts have been made to explain the origin of this term, ranging from the Italian root, a "rock," to the town of Rocca in Syria, where alum was supposed to have been produced. In any event, the supply for a long period prior to the middle of the 15th Century came from Turkey, and the origin of the methods of manufacture described by Agricola, and used down to the present day, must have come from the Orient.
In the early part of the 15th Century, a large trade in alum was done between Italy and Asia Minor, and eventually various Italians established themselves near Constantinople and Smyrna for its manufacture (Dudae, Historia Byzantina Venetia, 1729, p. 71). The alum was secured by burning the rock, and lixiviation. With the capture of Constantinople by the Turks (1453), great feeling grew up in Italy over the necessity of buying this requisite for their dyeing establishments from the infidel, and considerable exertion was made to find other sources of supply. Some minor works were attempted, but nothing much [Pg 570]eventuated until the appearance of one John de Castro. From the Commentaries of Pope Pius II. (1614, p. 185), it appears that this Italian had been engaged in dyeing cloth in Constantinople, and thus became aware of the methods of making alum. Driven out of that city through its capture by the Turks, he returned to Italy and obtained an office under the Apostolic Chamber. While in this occupation he discovered a rock at Tolfa which appeared to him identical with that used at Constantinople in alum manufacture. After experimental work, he sought the aid of the Pope, which he obtained after much vicissitude. Experts were sent, who after examination "shed tears of joy, they kneeling down three times, worshipped God and praised His kindness in conferring such a gift on their age." Castro was rewarded, and the great papal monopoly was gradually built upon this discovery. The industry firmly established at Tolfa exists to the present day, and is the source of the Roman alum of commerce. The Pope maintained this monopoly strenuously, by fair means and by excommunication, gradually advancing the price until the consumers had greater complaint than against the Turks. The history of the disputes arising over the papal alum monopoly would alone fill a volume.
By the middle of the 15th Century alum was being made in Spain, Holland, and Germany, and later in England. In her efforts to encourage home industries and escape the tribute to the Pope, Elizabeth (see Note on p. [283]) invited over "certain foreign chymistes and mineral masters" and gave them special grants to induce them to "settle in these realmes." Among them was Cornelius Devoz, to whom was granted the privilege of "mining and digging in our Realm of England for allom and copperas." What Devoz accomplished is not recorded, but the first alum manufacture on a considerable scale seems to have been in Yorkshire, by one Thomas Chaloner (about 1608), who was supposed to have seduced workmen from the Pope's alum works at Tolfa, for which he was duly cursed with all the weight of the Pope and Church. (Pennant, Tour of Scotland, 1786).
[Pg 572][11] The term for vitriol used by the Roman authors, followed by Agricola, is atramentum sutorium, literally shoemaker's blacking, the term no doubt arising from its ancient (and modern) use for blackening leather. The Greek term was chalcanthon. The term "vitriol" seems first to appear in Albertus Magnus (De Mineralibus, Liber V.), who died in 1280, where he uses the expression "atramentum viride a quibusdam vitreolum vocatur." Agricola (De Nat. Foss., p. 213) states, "In recent years the name vitriolum has been given to it." The first adequate description of vitriol is by Dioscorides (V., 76), as follows:—"Vitriol (chalcanthon) is of one genus, and is a solidified liquid, but it has three different species. One is formed from the liquids which trickle down drop by drop and congeal in certain mines; therefore those who work in the Cyprian mines call it stalactis. Petesius calls this kind pinarion. The second kind is that which collects in certain caverns; afterward it is poured into trenches, where it congeals, whence it derives its name pēctos. The third kind is called hephthon and is mostly made in Spain; it has a beautiful colour but is weak. The manner of preparing it is as follows: dissolving it in water, they boil it, and then they transfer it to cisterns and leave it to settle. After a certain number of days it congeals and separates into many small pieces, having the form of dice, which stick together like grapes. The most valued is blue, heavy, dense, and translucent." Pliny (XXXIV., 32) says:—"By the name which they have given to it, the Greeks indicate the similar nature of copper and atramentum sutorium, for they call it chalcanthon. There is no substance of an equally miraculous nature. It is made in Spain from wells of this kind of water. This water is boiled with an equal quantity of pure water, and is then poured into wooden tanks (fish ponds). Across these tanks there are fixed beams, to which hang cords stretched by little stones. Upon these cords adheres the limus (Agricola's 'juice') in drops of a vitreous appearance, somewhat resembling a bunch of grapes. After removal, it is dried for thirty days. It is of a blue colour, and of a brilliant lustre, and is very like glass. Its solution is the blacking used for colouring leather. Chalcanthon is made in many other ways: its kind of earth is sometimes dug from ditches, from the sides of which exude drops, which solidify by the winter frosts into icicles, called stalagmia, and there is none more pure. When its colour is nearly white, with a slight tinge of violet, it is called leukoïon. It is also made in rock basins, the rain water collecting the limus into them, where it becomes hardened. It is also made in the same way as salt by the intense heat of the sun. Hence it is that some distinguish two kinds, the mineral and the artificial; the latter being paler than the former and as much inferior to it in quality as it is in colour."
While Pliny gives prominence to blue vitriol, his solution for colouring leather must have been the iron sulphate. There can be no doubt from the above, however, that both iron and copper sulphates were known to the Ancients. From the methods for making vitriol given here in De Re Metallica, it is evident that only the iron sulphate would be produced, for the introduction of iron strips into the vats would effectually precipitate any copper. It is our belief that generally throughout this work, the iron sulphate is meant by the term atramentum sutorium. In De Natura Fossilium (p. 213-15) Agricola gives three varieties of atramentum sutorium,—viride, caeruleum, and candidum, i.e., green, blue, and white. Thus the first mention of white vitriol (zinc sulphate) appears to be due to him, and he states further (p. 213): "A white sort is found, especially at Goslar, in the shape of icicles, transparent like crystals." And on p. 215: "Since I have explained the nature of vitriol and its relatives, which are obtained from cupriferous pyrites, I will next speak of an acrid solidified juice which commonly comes from cadmia. It is found at Annaberg in the tunnel driven to the Saint Otto mine; it is hard and white, and so acrid that it kills mice, crickets, and every kind of animal. However, that feathery substance which oozes out from the mountain rocks and the thick substance found hanging in tunnels and caves from which saltpetre is made, while frequently acrid, does not come from cadmia." Dana (Syst. of Min., p. 939) identifies this as Goslarite—native zinc sulphate. It does not appear, however, that artificial zinc vitriol was made in Agricola's time. Schlüter (Huette-Werken, Braunschweig 1738, p. 597) states it to have been made for the first time at Rammelsberg about 1570.
[Pg 573] It is desirable here to enquire into the nature of the substances given by all of the old mineralogists under the Latinized Greek terms chalcitis, misy, sory, and melanteria. The first mention of these minerals is in Dioscorides, who (V., 75-77) says: "The best chalcitis is like copper. It is friable, not stony, and is intersected by long brilliant veins.... Misy is obtained from Cyprus; it should have the appearance of gold, be hard, and when pulverised it should have the colour of gold and sparkle like stars. It has the same properties as chalcitis.... The best is from Egypt.... One kind of melanteria congeals like salt in the entries to copper mines. The other kind is earthy and appears on the surface of the aforesaid mines. It is found in the mines of Cilicia and other regions. The best has the colour of sulphur, is smooth, pure, homogenous, and upon contact with water immediately becomes black.... Those who consider sory to be the same as melanteria, err greatly. Sory is a species of its own, though it is not dissimilar. The smell of sory is oppressive and provokes nausea. It is found in Egypt and in other regions, as Libya, Spain, and Cyprus. The best is from Egypt, and when broken is black, porous, greasy, and astringent." Pliny (XXXIV., 29-31) says:—"That is called chalcitis from which, as well as itself copper (?) is extracted by heat. It differs from cadmia in that this is obtained from rocks near the surface, while that is taken from rocks below the surface. Also chalcitis is immediately friable, being naturally so soft as to appear like compressed wool. There is also this other distinction; chalcitis contains three other substances, copper, misy, and sory. Of each of these we shall speak in their appropriate places. It contains elongated copper veins. The most approved kind is of the colour of honey; it is streaked with fine sinuous veins and is friable and not stony. It is considered most valuable when fresh.... The sory of Egypt is the most esteemed, being much superior to that of Cyprus, Spain, and Africa; although some prefer the sory from Cyprus for affections of the eyes. But from whatever nation it comes, the best is that which has the strongest odour, and which, when ground up, becomes greasy, black, and spongy. It is a substance so unpleasant to the stomach that some persons are nauseated by its smell. Some say that misy is made by the burning of stones in trenches, its fine yellow powder being mixed with the ashes of pine-wood. The truth is, as I said above, that though obtained from the stone, it is already made and in solid masses, which require force to detach them. The best comes from the works of Cyprus, its characteristics being that when broken it sparkles like gold, and when ground it presents a sandy appearance, but on the contrary, if heated, it is similar to chalcitis. Misy is used in refining gold...."
Agricola's views on the subject appear in De Natura Fossilium. He says (p. 212):—"The cupriferous pyrites (pyrites aerosus) called chalcitis is the mother and cause of sory—which is likewise known as mine vitriol (atramentum metallicum)—and melanteria. These in turn yield vitriol and such related things. This may be seen especially at Goslar, where the nodular lumps of dark grey colour are called vitriol stone (lapis atramenti). In the centre of them is found greyish pyrites, almost dissolved, the size of a walnut. It is enclosed on all sides, sometimes by sory, sometimes by melanteria. From them start little veinlets of greenish vitriol which spread all over it, presenting somewhat the appearance of hairs extending in all directions and cohering together.... There are five species of this solidified juice, melanteria, sory, chalcitis, misy, and vitriol. Sometimes many are found in one place, sometimes all of them, for one originates from the other. From pyrites, which is, as one might say, the root of all these juices, originates the above-mentioned sory and melanteria. From sory, chalcitis, and melanteria originate the various kinds of vitriol.... Sory, melanteria, chalcitis, and misy are always native; vitriol alone is either native or artificial. From them vitriol effloresces white, and sometimes green or blue. Misy effloresces not only from sory, melanteria, and chalcitis, but also from all the vitriols, artificial as well as natural.... Sory and melanteria differ somewhat from the others, but they are of the same colours, grey and black; but chalcitis is red and copper-coloured; misy is yellow or gold-coloured. All these native varieties have the odour of lightning (brimstone), but sory is the most powerful. The feathery vitriol is soft and fine and hair-like, and melanteria has the appearance of wool and it has a similarity to salt; all these are rare and light; sory, chalcitis, and misy have the following relations. Sory because of its density has the hardness of stone, although its texture is very coarse. Misy has a very fine texture. Chalcitis is between the two; because of its roughness and strong odour it differs from melanteria, although they do not differ in colour. The vitriols, whether natural or artificial, are hard and dense ... as regarding shape, sory, chalcitis, misy, and melanteria are nodular, but sory is occasionally porous, which is peculiar to it. [Pg 574]Misy when it effloresces in no great quantity from the others is like a kind of pollen, otherwise it is nodular. Melanteria sometimes resembles wool, sometimes salt."
The sum and substance, therefore, appears to be that misy is a yellowish material, possibly ochre, and sory a blackish stone, both impregnated with vitriol. Chalcitis is a partially decomposed pyrites; and melanteria is no doubt native vitriol. From this last term comes the modern melanterite, native hydrous ferrous sulphate. Dana (System of Mineralogy, p. 964) considers misy to be in part copiapite—basic ferric sulphate—but any such part would not come under Agricola's objection to it as a source of vitriol. The disabilities of this and chalcitis may, however, be due to their copper content.
[Pg 578][12] Agricola (De Nat. Fos., 221) says:—"There is a species of artificial sulphur made from sulphur and iron hammer-scales, melted together and poured into moulds. This, because it heals scabs of horses, is generally called caballinum." It is difficult to believe such a combination was other than iron sulphide, but it is equally difficult to understand how it was serviceable for this purpose.
[13] Inasmuch as pyrites is discussed in the next paragraph, the material of the first distillation appears to be native sulphur. Until the receiving pots became heated above the melting point of the sulphur, the product would be "flowers of sulphur," and not the wax-like [Pg 579]product. The equipment described for pyrites in the next paragraph would be obviously useful only for coarse material.
But little can be said on the history of sulphur; it is mentioned often enough in the Bible and also by Homer (Od. XXII., 481). The Greeks apparently knew how to refine it, although neither Dioscorides nor Pliny specifically describes such an operation. Agricola says (De Nat. Fos., 220): "Sulphur is of two kinds; the mineral, which the Latins call vivum, and the Greeks apyron, which means 'not exposed to the fire' (ignem non expertum) as rightly interpreted by Celsius; and the artificial, called by the Greeks pepyromenon, that is, 'exposed to the fire.'" In [Book X.], the expression sulfur ignem non expertum frequently appears, no doubt in Agricola's mind for native sulphur, although it is quite possible that the Greek distinction was between "flowers" of sulphur and the "wax-like" variety.
[Pg 581][14] The substances referred to under the names bitumen, asphalt, maltha, naphtha, petroleum, rock-oil, etc., have been known and used from most ancient times, and much of our modern nomenclature is of actual Greek and Roman ancestry. These peoples distinguished three related substances,—the Greek asphaltos and Roman bitumen for the hard material,—Greek pissasphaltos and Roman maltha for the viscous, pitchy variety—and occasionally the Greek naphtha and Roman naphtha for petroleum proper, although it is often enough referred to as liquid bitumen or liquid asphaltos. The term petroleum apparently first appears in Agricola's De Natura Fossilium (p. 222), where he says the "oil of bitumen ... now [Pg 582]called petroleum." Bitumen was used by the Egyptians for embalming from pre-historic times, i.e., prior to 5000 B.C., the term "mummy" arising from the Persian word for bitumen, mumiai. It is mentioned in the tribute from Babylonia to Thotmes III., who lived about 1500 B.C. (Wilkinson, Ancient Egyptians I., p. 397). The Egyptians, however, did not need to go further afield than the Sinai Peninsula for abundant supplies. Bitumen is often cited as the real meaning of the "slime" mentioned in Genesis (XI., 3; XIV., 10), and used in building the Tower of Babel. There is no particular reason for this assumption, except the general association of Babel, Babylon, and Bitumen. However, the Hebrew word sift for pitch or bitumen does occur as the cement used for Moses's bulrush cradle (Exodus II., 3), and Moses is generally accounted about 1300 B.C. Other attempts to connect Biblical reference to petroleum and bitumen revolve around Job XXIX., 6, Deut. XXXII., 13, Maccabees II., I, 18, Matthew V., 13, but all require an unnecessary strain on the imagination.
The plentiful occurrence of bitumen throughout Asia Minor, and particularly in the Valley of the Euphrates and in Persia, is the subject of innumerable references by writers from Herodotus (484-424 B.C.) down to the author of the company prospectus of recent months. Herodotus (I., 179) and Diodorus Siculus (I) state that the walls of Babylon were mortared with bitumen—a fact partially corroborated by modern investigation. The following [Pg 583]statement by Herodotus (VI., 119) is probably the source from which Pliny drew the information which Agricola quotes above. In referring to a well at Ardericca, a place about 40 miles from ancient Susa, in Persia, Herodotus says:—"For from the well they get bitumen, salt, and oil, procuring it in the way that I will now describe: they draw with a swipe, and instead of a bucket they make use of the half of a wine-skin; with this the man dips and, after drawing, pours the liquid into a reservoir, wherefrom it passes into another, and there takes three different shapes. The salt and bitumen forthwith collect and harden, while the oil is drawn off into casks. It is called by the Persians rhadinace, is black, and has an unpleasant smell." (Rawlinson's Trans. III., p. 409). The statement from Pliny (XXXI., 39) here referred to by Agricola, reads:—"It (salt) is made from water of wells poured into salt-pans. At Babylon the first condensed is a bituminous liquid like oil which is burned in lamps. When this is taken off, salt is found beneath. In Cappadocia also the water from both wells and springs is poured into salt-pans." When petroleum began to be used as an illuminant it is impossible to say. A passage in Aristotle's De Mirabilibus (127) is often quoted, but in reality it refers only to a burning spring, a phenomenon noted by many writers, but from which to its practical use is not a great step. The first really definite statement as to the use of petroleum as an [Pg 584]illuminant is Strabo's quotation (XVI., 1, 15) from Posidonius: "Asphaltus is found in great abundance in Babylonia. Eratosthenes describes it as follows:—The liquid asphaltus, which is called naphtha, is found in Susa; the dry kind, which can be made solid, in Babylonia. There is a spring of it near the Euphrates.... Others say that the liquid kind is also found in Babylonia.... The liquid kind, called naphtha, is of a singular nature. When it is brought near the fire, the fire catches it.... Posidonius says that there are springs of naphtha in Babylonia, some of which produce white, others black naphtha; the first of these, I mean white naphtha, which attracts flame, is liquid sulphur; the second or black naphtha is liquid asphaltus, and is burnt in lamps instead of oil." (Hamilton's Translation, Vol. III., p. 151). Eratosthenes lived about 200 B.C., and Posidonius about 100 years later. Dioscorides (I., 83), after discussing the usual sources of bitumen says: "It is found in a liquid state in Agrigentum in Sicily, flowing on streams; they use it for lights in lanterns in place of oil. Those who call the Sicilian kind oil are under a delusion, for it is agreed that it is a kind of liquid bitumen." Pliny adds nothing much new to the above quotations, except in regard to these same springs (XXXV., 51) that "The inhabitants collect it on the panicles of reeds, to which it quickly adheres and they use it for burning in lamps instead of oil." Agricola (De Natura Fossilium, Book IV.) classifies petroleum, coal, jet, and obsidian, camphor, and amber as varieties of bitumen, and devotes much space to the refutation of the claims that the last two are of vegetable origin.
[15] Agricola (De Natura Fossilium, p. 215) in discussing substances which originate from copper, gives among them green chrysocolla (as distinguished from borax, etc., see [Note 8 above]), and says: "Native chrysocolla originates in veins and veinlets, and is found mostly by itself like sand, or adhering to metallic substances, and when scraped off from this appears similar to its own sand. Occasionally it is so thin that very little can be scraped off. Or else it occurs in waters which, as I have said, wash these minerals, and afterward it settles as a powder. At Neusohl in the Carpathians, green water flowing from an ancient tunnel wears away this chrysocolla with it. The water is collected in thirty large reservoirs, where it deposits the chrysocolla as a sediment, which they collect every year and sell,"—as a pigment. This description of its occurrence would apply equally well to modern chrysocolla or to malachite. The solution from copper ores would deposit some sort of green incrustation, of carbonates mostly.
[Pg 585][16] The statement in Pliny (XXXVI., 66) to which Agricola refers is as follows: "Then as ingenuity was not content with the mixing of nitrum, they began the addition of lapis [Pg 586]magnes, because of the belief that it attracts liquefied glass as well as iron. In a similar manner many kinds of brilliant stones began to be added to the melting, and then shells and fossil sand. Authors tell us that the glass of India is made of broken crystal, and in consequence nothing can compare with it. Light and dry wood is used for fusing, cyprium (copper?) and nitrum being added, particularly nitrum from Ophir etc."
A great deal of discussion has arisen over this passage, in connection with what this lapis magnes really was. Pliny (XXXVI., 25) describes the lodestone under this term, but also says: "There (in Ethiopia) also is haematites magnes, a stone of blood colour, which shows a red colour if crushed, or of saffron. The haematites has not the same property of attracting iron as magnes." Relying upon this sentence for an exception to the ordinary sort of magnes, and upon the impossible chemical reaction involved, most commentators have endeavoured to show that lodestone was not the substance meant by Pliny, but manganese, and thus they find here the first knowledge of this mineral. There can be little doubt that Pliny assumed it to be the lodestone, and Agricola also. Whether the latter had any independent knowledge on this point in glass-making or was merely quoting Pliny—which seems probable—we do not know. In any event, Biringuccio, whose work preceded De Re Metallica by fifteen years, does definitely mention manganese in this connection. He dismisses this statement of Pliny with the remark (p. 37-38): "The Ancients wrote about lodestones, as Pliny states, and they mixed it together with nitrum in their first efforts to make glass." The following passage from this author (p. 36-37), however, is not only of interest in this connection, but also as possibly being the first specific mention of manganese under its own name. Moreover, it has been generally overlooked in the many discussions of the subject. "Of a similar nature (to zaffir) is also another mineral called manganese, which is found, besides in Germany, at the mountain of Viterbo in Tuscany ... it is the colour of ferrigno scuro (iron slag?). In melting it one cannot obtain any metal ... but it gives a very fine colour to glass, so that the glass workers use it in their pigments to secure an azure colour.... It also has such a property that when put into melted glass it cleanses it and makes it white, even if it were green or yellow. In a hot fire it goes off in a vapour like lead, and turns into ashes."
To enter competently into the discussion of the early history of glass-making would employ more space than can be given, and would lead but to a sterile end. It is certain that the art was pre-Grecian, and that the Egyptians were possessed of some knowledge of making and blowing it in the XI Dynasty (according to Petrie 3,500 B.C.), the wall painting at Beni Hassen, which represents glass-blowing, being attributed to that period. The remains of a glass factory at Tel el Amarna are believed to be of the XVIII Dynasty. (Petrie, 1,500 B.C.). The art reached a very high state of development among the Greeks and Romans. No discussion of this subject omits Pliny's well-known story (XXXVI, 65), which we also add: "The tradition is that a merchant ship laden with nitrum being moored at this place, the merchants were preparing their meal on the beach, and not having stones to prop up their pots, they used lumps of nitrum from the ship, which fused and mixed with the sands of the shore, and there flowed streams of a new translucent liquid, and thus was the origin of glass."