Pints. Quarts. Gallons.

1 _Cyathus_ .08 3 _Cyathi_ = 1 _Quartarius_ .24 4 _Quartarii_ = 1 _s.e.xtarius_ .99 6 _s.e.xtarii_ = 1 _Congius_ 5.94 2.97 16 _s.e.xtarii_ = 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.

[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.

[5] Pliny x.x.xI., 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 pota.s.sium 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 x.x.xI., 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 gla.s.s, 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 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 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% K_{2}CO_{3}, the remainder being sodium and pota.s.sium sulphates. Another reason for a.s.suming 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 ill.u.s.tration of soda-making from Nile water is no doubt founded upon Pliny (x.x.xI., 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 a.s.sertion of Biringuccio (II., 9).

SAL-AMMONIAC.--The early history of this--ammonium chloride--is also under a cloud. Pliny (x.x.xI., 39) speaks of a _sal-hammoniac.u.m_, 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-ammoniac.u.m_, and describes a method of making, and several characteristic reactions. It was known in the Middle Ages under various names, among them _sal-aremonic.u.m_. 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 x.x.xIII., 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 (x.x.xIII., 26, 27, 28, and 29, x.x.xV., 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.

[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 pota.s.sium and calcium carbonates--the lye and lime--form pota.s.sium 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(NO_{3})_{2} + K_{2}CO_{3} = CaCO_{3} + 2KNO_{3}. 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 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 pota.s.sium 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.

[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 a.s.suming 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 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 pota.s.sium), 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 pota.s.sium 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 gla.s.s, 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." a.s.suming the oil of vitriol to be sulphuric acid and the clay "used in cementing gla.s.s" 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 is now general. One of the strongest reasons put forward was that alum does not occur native in appreciable quant.i.ties. 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 quant.i.ty 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 (x.x.xV., 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 (x.x.xV., 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 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 sc.u.m 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 (x.x.xV., 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 circ.u.mstance 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 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 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 G.o.d 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).

[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 _pectos_. 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 (x.x.xIV., 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 quant.i.ty 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 l.u.s.tre, and is very like gla.s.s. 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 _leukoon_. 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. Schluter (_Huette-Werken_, Braunschweig 1738, p. 597) states it to have been made for the first time at Rammelsberg about 1570.

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, h.o.m.ogenous, 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 (x.x.xIV., 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 ma.s.ses, 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 metallic.u.m_)--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 coa.r.s.e. _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.

_Misy_ when it effloresces in no great quant.i.ty 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.

[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 product.

The equipment described for pyrites in the next paragraph would be obviously useful only for coa.r.s.e 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.

[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 _p.i.s.sasphaltos_ 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 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 a.s.sumption, except the general a.s.sociation 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. x.x.xII., 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 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 pa.s.ses 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 (x.x.xI., 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 pa.s.sage 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 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....