A History of Inventions, Discoveries, and Origins, Volume II (of 2)

The similarity of wood-ashes to the nitrum of the ancients, which they acknowledged, proves also that it was in reality an alkaline salt. We are told by Theophrastus[1206 - Hist. Plant. iii. 9, p. 50.] that nitrum was said to be produced from oak-ashes; and Pliny[1207 - xxvi. 8.], who borrowed from this writer, remarks that it was certain the ashes of that wood were nitrous. He ascribes also to burnt wine-lees the nature and properties of nitrum[1208 - xiv. 20.]. Nay he considers as a kind of nitrum those saline ashes which, in many countries destitute of salt, were used for seasoning food, and which were prepared by pouring sea-water or salt brine over burning piles of wood, gradually and in small quantities, so that the fire was not extinguished, by which means the water evaporated, leaving the salt behind, but mixed indeed with charcoal, ashes, earth, and alkaline salts; consequently it must have been moist, or at any rate nauseous, if not refined by a new solution. This method of preparing or boiling salt, which perhaps is the oldest, has been mentioned by various writers; but many of them, through ignorance or neglect, have not told us that sea-water or brine was employed, as they speak in such a manner as if any kind and even fresh water had been used for that purpose.

Varro relates that he saw this process employed on the Rhine[1209 - De Re Rustica, lib. i. c. 7. Little, however, depended on the wood; the principal thing was the sprinkling with water.]. Pliny says[1210 - xxxi. 10.] that oak timber had before been burnt for that purpose. In another place he mentions a similar process among the Gauls and the Germans[1211 - xxxi. 7. Here express mention is made of brine.], as Tacitus does among the Hermanduri and the Catti[1212 - Taciti Annal. xiii. 57.]. The former also states, on the authority of Theophrastus, that the Umbri burnt salt in the like manner[1213 - Lib. xxx. 7.]. It is however certain that Pliny and other ancient writers often quote from Theophrastus what, at present, is not to be found in the works of that naturalist, but in those of his preceptor Aristotle[1214 - This is particularly the case in regard to Aristot. Auscult. Mirab., as I have remarked in the preface to my edition.].

Pliny adds, that this paltry method of obtaining salt had been long given up; and this indeed was the natural consequence of increased civilization. It is however certain that it was long continued in many countries, and in some still exists.

About two centuries ago the inhabitants of the province of Zeeland, descendants perhaps of the Catti, used no other salt than what they obtained in the like manner, from mud thrown up by the sea, which they burned and moistened with sea-water, as we are told by Lemnius, who was himself a native of that country. Boxhorn says, in his annotations on the above-quoted passage of Tacitus, that he saw a painting at Zirkzee, in which the whole process was represented. It is probable that salt was boiled exactly in the same manner as at some of the Sleswic islands, described by Denkwerth[1215 - In the island of Dagebull, and also in Faretoft and Galmesbull, Frisio salt is made in the following manner. The inhabitants proceed along the coast in small vessels, and at low water go on shore on the mud, which they dig up till they come to a kind of earth called torricht; it is of a turfy nature, and interwoven with roots. This earth they convey to the islands, where they spread it out in the sun and leave it to dry, after which it is formed into a heap and burnt to ashes. What remains is again spread out, moistened and trod upon with the naked feet; the small stones and other useless parts are picked out, and being again dried and besprinkled with water, the ley is put into salt-pans and boiled into salt.], from whose account it is seen that the glebæ marinæ, of which Lemnius speaks, consisted of mud mixed with roots growing in them; and that the salt when afterwards refined was called there Frisic, in all probability because the inhabitants had learned to make it from their ancestors the Frieslanders. I remember somewhere to have read that salt was made for a long time in this manner by the so-called Wurst-Frieslanders, in the country of Wurst, belonging to the duchy of Bremen. The inhabitants also of the Austrian part of Moldavia, or Buccowina as it is called, still use a salt, which they do not boil, but burn with their superfluous wood, in the like manner from the brine of a saline spring. A member of the former Academy of Brussels[1216 - Mémoires de l’Acad. de Bruxelles, 1777, i. p. 345.] took the trouble to examine the process as described by the ancients, and obtained, as might certainly have been expected, a highly alkaline kind of common salt, similar to that which Pliny, not without reason, considered as a sort of nitrum, because undoubtedly it may oftener have been an alkaline carbonate than common salt.

Boerhaave[1217 - Elementa Chemiæ. Lugd. Bat. 1732, 4to, i. p. 767.], in quoting the passages of the ancients, did not reflect that, during the incineration of the wood, salt water was poured over it. He considered the whole process as a burning of potash, and thought that the salt obtained was fit for use only because it was made according to the manner of Tachenius. That indeed gives a carbonated salt, which is almost saponaceous, and so mixed with various parts of the burnt plants that it is much milder, consequently fitter for use than common soda or pearlash can be; but that salt was not so much of the Tachenian kind as a species of common salt superabundant in alkali.

If the nitrum was carbonated alkali, there is reason to suppose that the ancients must have occasionally mentioned in their writings that it effervesced with acids. With the mineral acids indeed they were not acquainted; but they had vinegar, and that nitrum produced with this an effervescence had been known in the oldest times. A very clear allusion to this circumstance is found in the book of Proverbs, chap. xxv. ver. 20; where Luther however translates the word by chalk. Jerome, whose explanation I have already quoted, was in some degree acquainted with this phænomenon; and therefore to him the comparison of Solomon was intelligible[1218 - Boyle considered the words of Solomon as a proof that nether must be fixed alkali; and he was the more convinced of it when he saw nitre obtained from Egypt effervesce with acids.]. But at present I can produce no proofs from Greek writers; though they might have occurred during the use of nitrum in medicine, in consequence of which it was often put into vinegar.

We shall be further convinced what nitrum really was, when the uses to which it was applied, as mentioned in the works of the ancients, are considered. The most common, as soap was not then known, appears to have been in washing, a purpose for which our saltpetre would not be fit; besides, it is at all times too scarce and too dear. I shall not here adduce any proofs of its being employed in this manner, as they often occur, and as several have been already given in the preceding volume[1219 - See the History of Soap (#soap) in vol. i.]. Many salves and cosmetics were prepared with nitrum; and in all probability articles of this kind, used chiefly among the women, are to be understood by the term nitron parthenicon, which occurs in Nicholas Myrepsius, in the beginning of the fourteenth century; matronicon, mentioned by the same, and by Alexander of Tralles, about the year 565; and the nitrum matronale of Marcellus Empiricus, in the fifth century. That the use of it for washing still continues in the East, is confirmed in various books of travels.

The oldest glass, of the preparation of which any account is to be found in history, was made by means of nitrum or mineral alkali. For though I doubt that it could have been produced on the sandy banks of the Belus, where some merchants, when cooking, supported their pots with lumps of nitrum[1220 - Plin. xxxvi. 26, § 65. The use of nitrum in making glass is often mentioned.], because sand is not so easily brought to a state of fusion; it at any rate remains certain, that this supposed fusion with our saltpetre is altogether impossible.

The use of nitrum for painting announces, without doubt, an alkaline carbonate, and not saltpetre[1221 - Plin. xxxi. 10.]; and the case is the same with the various uses in the cookery of the ancients, many of which we have still retained. It was added to bread in baking, according to Pliny[1222 - Lib. xxx. 10.], in the stead of salt, but probably to promote its rising, for which purpose it is still employed by the Egyptians, as potash was by our bakers. For this use the mineral alkali was formerly brought from the Levant to France, till it was declared by the physicians to be injurious to the health[1223 - Forskäl Flora, p. xlvi.].

When meat which was too fresh was to be dressed, it was put into nitrum[1224 - Plutarchi Sympos. lib. vi. at the end.], in order to make it tender; and, according to Forskäl and others, this is still practised in the East. Our cooks also know that smoked meat, fish and other dried provisions become more tender when placed in a ley of potash, or when a little potash is added while they are boiling.

Nitrum, however, was employed for curing articles of food which people wished to preserve. This appears to contradict what has been mentioned above; but in all probability a caustic sort was used for the former purpose; but for the latter a mild kind, mixed with a great deal of common salt. There were so many species, that some of them might have been applied to quite contrary purposes.

As I conjecture, the use of nitrum for causing chestnuts and other husky fruits to boil soft, was also known: to produce the same effect, potash is at present thrown among boiling lentils and peas. I am inclined to think that for this reason Apicius caused chestnuts to be boiled with nitre.

It is highly probable that this effect of alkaline carbonates induced agriculturists to believe that beans, peas, lentils and other leguminous fruits, if steeped, before they were sown, in water in which nitre had been dissolved, or if the dung spread over the earth had been mixed with nitre, the future product could be more easily boiled soft[1225 - Theophrasti Histor. Plant. ii. 5. – Geopon. ii. 35, 2; and ii. 41. – Palladius, xii. tit. i. 3, p. 996.]. However useful this addition may be in cookery, it would produce little effect on seed; and it appears to me that the old agriculturists placed little confidence in the last-mentioned use, because they were not agreed in regard to the result. Virgil and others seem to expect from it an increase of the fruit[1226 - Virg. Georg. i. 193. – Plin. xviii. 7. 845. – Geopon. ii. 36, p. 184.]; but others, security against beetles, which eat the fruit and leave the husks empty[1227 - Columella, ii. 10, 11.]. When cabbages were transplanted they were strewed over with nitre, and by these means were said to come sooner to maturity[1228 - Plin. xix. 8, § 41. – Pallad. iii. 24, 6. – Geopon. xii. 17, 1. – Theophrast. de Causa Plant. vi. 14.]. Radishes also were treated in the same manner, or besprinkled with nitrous water, in order to make them more tender[1229 - Plin. xxxi. 10; and xix. 5, § 26, 10.].

A common method employed by the ancient cooks to give a beautiful green colour to pickled or boiled vegetables, was to add nitrum to them while boiling; but this effect could be produced by natrum, and not by the nitrum of the moderns, or that neutral salt called saltpetre[1230 - Apicius, iii. 1, p. 70. – Martial, lib. xiii. ep. 17. – Plin. xix. 8, § 41, 3; xxx. 10. – Columella, xi. 3, 23. [Carbonate of soda, as is well known, is still frequently used for this purpose in culinary operations.]].

Among the oldest accounts of nitrum is that where it is mentioned as being employed for embalming dead bodies. It would be tiresome to read over and examine everything written on that subject by the learned; but this much I think is clear, that either the flesh, and in general the softer parts of the body could be corroded in the course of seventy days by the Egyptian nitrum[1231 - Herodot. ii. 87.], which, as above shown, was burnt, and in general mixed with unslaked lime, and consequently caustic[1232 - Our tanners use unslaked lime for a similar purpose.]; or that the moist parts could be desiccated by carbonate alkali, in the same manner as the manufacturers of parchment purify and dry their skins by the application of chalk. That saltpetre in no case could be useful for this purpose needs hardly be mentioned.

The ancient physicians, who were unacquainted with our numerous class of salts, employed their nitrum in many ways, and for a great variety of mixtures; but no writer, as far as I know, ever took the trouble to examine these recipes, though it has long since been declared that nitrum must have been potash or salt of tartar. Matthioli[1233 - Annot. to Dioscorides, v. 89, p. 951.] asserted, that those physicians would act very improperly who should prescribe our saltpetre where the ancients employed their nitrum; and indeed those in the least acquainted with the effects of salts must know, that all those extolled by the ancients announce carbonated alkalies. Thus burnt nitrum was employed for cleaning black teeth, as at present many use tobacco ashes instead of tooth-powder. It is seen by the works of Aretæus and others, that burnt nitrum was used as a caustic, till people learned in modern times to prepare the more active causticum potentiale, or sal causticum.

What the ancients say of the taste of their nitrum seems, however, not entirely applicable to pure carbonated alkali; and much less, or not at all, to our saltpetre. Had they meant the latter, they would certainly not have failed to mention the sensation of coolness which it occasions when applied to the tongue. Galen and Aetius say, that nitrum is as bitter as gall; but Serapio ascribes to it a saline taste, with a small degree of bitterness; as does also Pliny, only that for bitterness he substitutes the word sharpness. The names of tastes, however, are as uncertain as the names of the colours which occur in the works of the ancients. Both certainly deserve to be more accurately examined, and to be defined by comparing the things to which these names are given. Prosper Alpinus, however, is of opinion that what the ancients called amarum, is not inapplicable to the taste of natrum.

The ancients mention various springs and streams which contained what they called nitrum[1234 - A catalogue of such waters may be found in Baccii Liber de Thermis. Patavii, 1711, fol. v. 5, 6, 7, p. 160. [Carbonate of soda occurs for instance in the celebrated mineral waters of Seltzer and Carlsbad, and also in the volcanic springs of Iceland, especially the Geyser.]]; but nitrous water, according to the present acceptation of the word, that is, water which contains saltpetre, does not exist; and if credit is to be given to Marggraf and others, that they observed traces of saltpetre in some kinds of water, the instances must have been so rare that mention of them could not be expected among the ancients. Their nitrous water was undoubtedly alkaline, and this indeed is not scarce. Such water was recommended by the ancient physicians, both for bathing and drinking[1235 - Plin. xxxi. 6, § 32, p. 556. Vitruv. viii. 3, p. 158.]; and Pliny says, it was singular that the salt of such water would not shoot into crystals, like common salt, which is undoubtedly true[1236 - xxxi. 10.].

Alkaline water of this kind, such as that of Armenia, was used for washing, and also by fullers. In Egypt, at present, people wash in the same manner with nitrum.

It appears to me that many kinds of water, which were only impure and not potable on account of their nauseous taste, were considered by the ancients as nitrous. This seems to be proved by the means which they propose for rendering nitrous water fit to be drunk; that is, by throwing into it clay, or some grains of barley[1237 - Plin. xxiv. 1; xxxi. 3, § 22. Geopon. ii. 5, 14, p. 85.]. In the like manner, I saw the brewers at Amsterdam improve their dirty water, in some degree, by putting into it kneaded clay, and allowing it to sink to the bottom.

One foundation more for my assertion may be found, I think, in the name borax. The ancient nitrum by the Arabians was called Bauracon or Baurach. When that salt, which at present is everywhere called borax, became known to the Arabians, it was at first generally considered as a kind of nitre, and on that account called Baurach, because in most of its properties it approached near to the nitrum of the ancients, that is, the natrum of the present day. But afterwards, when the difference became known, our borax, at least in Europe, retained exclusively the general name of Baurach, from which at length was formed the present word borax. My conclusion therefore is, that the nitrum of the ancients must have been mineral alkali; otherwise it is impossible that our borax, which till modern times was reckoned to be mineral alkali, should have been considered as a nitrum.

For many centuries past, the people in Africa and Asia, and also in Spain and Sicily, have cultivated some kinds of plants, which they dry and then burn to ashes. By regulating the fire in a particular manner, they cause these ashes to assume a certain degree of concretion, or vitrification, by which means they are formed into solid cakes of a grey colour, interspersed with many white and black spots. This substance, which in consequence of the vitrification does not become moist in the air, is broken into fragments, and sent to every part of Europe under the name of soda, for the use of the glass-houses, soap-boilers, dyers, and for other purposes.

These plants were undoubtedly first cultivated and employed in Europe by the Arabians, who made known the use of them. Those first or chiefly employed were named by them axnan, usnan, usnen, or uscnanon; and also Hasciscio alcali, that is, herba kali, the plant or herb kali, because the name kali, or, with the article prefixed, al kali, was not given to the plant but to the half-vitrified ashes kali. Hence the chemists call salts obtained from the ashes of plants, alkaline salts. I do not know how old this appellation may be; but it is to be found in Vincent Bellovacensis and in the interpolated writings of Geber and Avicenna, and particularly in a passage quoted by the former from an old alchemist named Jahie, where it is called sal alchali[1238 - Speculum Naturæ, vii. 87, p. 480.]. All these salts formerly were considered as nitrous salts, or a kind of nitrum. It was indeed soon observed that soda and wood-ashes, which from the earliest periods had been burnt in woody districts, and which are now called potash, were not all of the same nature; but when the difference between the mineral and vegetable alkalies began to be studied, it was then known that soda contains the former, that is, our natrum, and potash the latter, but both indeed often rendered impure by earthy and foreign saline particles; and that there are many plants from the ashes of which mineral and not vegetable alkali is obtained. A question now arises, How old in the Levant is the method of preparing this natrum from the ashes of plants?

Michaelis is of opinion that it is mentioned in Malachi, chap. iii. ver. 2; which passage I shall give according to Luther’s translation: “Who shall stand when he appeareth? for he is like the fire of the goldsmith, and the soap of the scourer. He will sit and melt and purify the silver, and make pure like gold and silver.” This learned man here seems to think that the sacred writer alludes to refining the noble metals, and that the word borith means soda, which indeed may serve as a flux in the purification of them. I at first considered this meaning as true; but, on closer examination, I am fully convinced that we have both erred.

Those who read without prejudice the above passage of Malachi, must remark, that a double comparison or double image is employed. The messenger there promised was to separate the good from the bad, the clean from the unclean. The first occupation is compared with the labour of the gold-refiner; the other, with that of the scourer of clothes. The first image is afterwards heightened, because the poet, in all probability, was desirous of applying the separation of the ignoble parts, such as slag, by means of fire, as being the stronger image which denotes punishment, in a closer manner to the Levites and priests. At the time of the poet, before the invention of soap, people employed for washing either nitre or the saponaceous juice of certain plants, which I have already endeavoured to determine. The borith of the washer there expressly named, was undoubtedly one of these soap plants, and not the half-vitrified ashes either of soda or potash.

This passage of Malachi was so understood in the oldest times. Professor Tychsen, a true pupil and intimate friend of Michaelis, to whose opinion I subjected my doubts, assured me that Michaelis was never able to convince him of the justness of his exposition; especially as Jerome[1239 - Hieronym. ad Jerem. ii. 22.], without the least hesitation, understood borith to be a plant growing in Palestine, and used there for washing; and as the Greek translators, who were much nearer to the period of the poet, and could not be unacquainted with a thing so much used, have translated borith by the word ποα, a plant.

In Jeremiah, chap. ii. ver. 22[1240 - “For though thou wash thee with nitre, and take much soap, yet thine iniquity is marked before me, saith the Lord God.”], both the substances formerly used for washing, nitrum and the soap-plant, are so clearly named, that Michaelis was obliged to admit that we cannot understand there soda or potash, but a ley or soap, the last of which however was not at that time known. But, to speak the truth, potash and soda would not be altogether unfit for washing; at any rate, not less fit than the nether or nitrum there named. What may serve, however, to refute entirely the opinion of Michaelis is, that no proof has yet been found that soda is of so great antiquity. For my part, I am acquainted with no older mention of it than that which occurs in the works of the more modern Arabian physicians, Avicenna, Serapio, and others[1241 - In regard to the two plants usnee, asne, and usnem, assuan, see Avicennæ Canon. Medic. Venet. 1608, fol. pp. 338, 406, 407. Serapio de Temperam. Simplic. p. 164. In Du Cange’s Gloss. Gr. p. 12, addend. ἀλκαλη, and in Gloss. Lat. v. the word alcali is quoted only from modern writers. That kali, however, does not mean the plant, but the concrete ashes, is proved by the explanation in Castelli’s Lexicon.].

All these grounds afford sufficient proof that the nitrum of the ancients was our natrum, and not our saltpetre. But still, in the account given by the ancients of that salt, there remain many things inexplicable. Thus, for example, no one can accurately define the epithets, chalastricum, halmirhaga, agrium, spuma nitri, aphronitrum, and others, because they do not indicate different kinds, as already said, but accidental properties of the same salt. Without enlarging further on this subject, I shall only remark that Pliny admits a natural and an artificial kind of nitrum, and this division is adopted by Serapio; but the latter term has not the meaning which we affix to it at present. The ancients were acquainted with no other than native nitrum, which they called artificial only when it required a little more trouble and art to obtain it.

Most of the physicians recommend red nitrum, which is mentioned also by many of the modern travellers. When Prosper Alpinus was in Egypt the rose-red nitrum cost twice as much as the white. The red colour, in all probability, arises from a metallic admixture; yet the red nitrum may be purer than the other, as red or violet rock-salt is often clearer and purer than that which is colourless.

One of the darkest parts in the history of nitrum is the following passage of Pliny: “Faciunt ex his vasa, nec non frequenter liquatum cum sulphure, coquentes in carbonibus.” The latter words he seems soon after to repeat: “Sal nitrum sulphuri concoctum in lapidem vertitur.” From these words J. Rhodius[1242 - In the annotations to Scribonius Largus, p. 228.] concludes that nitrum fixum was at that time known, because he considered nitrum to be saltpetre; but in that case with the sulphur, Glaser’s sal polychrest must properly have been produced. This, however, was not the case, because nitrum was fixed alkali. The ancients therefore, when they placed it with sulphur in a crucible upon burning coals must have obtained liver of sulphur, which when it cools is hard, but soon becomes moist when exposed to the air. But I will not venture to determine whether anything of this kind is to be supposed in Pliny, who did not himself fully understand the subject on which he touches.

The account of vessels made of nitrum is still more singular. Michaelis conjectured[1243 - Commentationes, p. 145. Recueil des Questions, &c., p. 231.] that articles of various kinds were cut out of this substance, not for real use but merely for ornament, in the same manner as similar things are cut out of rock-salt in Transylvania, many specimens of which I have in my collection[1244 - Such things were known to Aristotle. See Mirab. Ausc. c. 146.]. But even if nitrum had been compact and strong enough for this purpose, there could not be the same inducement to employ it as rock-salt, which, in consequence of its solidity, transparency, brightness and smoothness, appears to be capable of furnishing vessels equal to those made of the most beautiful crystal. Dalechamp seems to explain the whole as applicable to glazing; but in this case nitrum could serve only as a flux.

Though it can be certainly proved that the nitrum of the ancients was an alkaline salt, it is difficult to determine the time when our saltpetre was discovered or made known. As many have conjectured that it was a component part of the Greek fire, invented about the year 678, which, in all probability, gave rise to the invention of gunpowder, I examined the prescriptions for the preparation of it. The oldest, and perhaps the most certain, is that given by the princess Anna Comnena; in which however I find only resin, sulphur and oil, but not saltpetre. Klingenstierna[1245 - Dissertat. de Igne Græco. Upsaliæ, 1752.] therefore judged very properly, that all recipes in which saltpetre occurs are either forged or of modern invention. Of this kind are those which Scaliger, at least according to his own account, found in Arabic works, and in which mention is made of oleum de nitro and sal petræ[1246 - De Subtilitate, xiii. 3. p. 71. ed. Francof. 1612, 8vo.]. But it does not occur in that prescription given by Marcus Græcus, and copied by Albertus Magnus, who died in 1280[1247 - De Mirabilibus Mundi, p. 201; at the end of the book De Secretis Mulierum. Amst. 1702, 12mo.].

I must still believe that the first certain mention of saltpetre will be found in the oldest account of the preparation of gunpowder, which, in my opinion, became known in Europe in the thirteenth century, about the same time that the use of the Greek fire, of which there were many kinds, began to be lost. Among the oldest information on this subject is that found in the above-quoted work of Albertus Magnus, and the writings of Roger Bacon, who died in 1278. It is doubted whether the first-mentioned treatise belongs to Albertus; but it is certain that the author, whoever he may have been, and also Bacon, both derived their information from the same source.

When M. von Arretin lately announced that he was about to publish a manuscript preserved in the electoral library at Munich, which contained the true recipe for making the Greek fire and the oldest for gunpowder, the same writing, as appears, was printed from two manuscripts in the library at Paris. I have now before me a copy of it, which was transmitted to the library of our university by M. Laporte Dutheil, conservateur des Manuscrits de la Bibliothèque[1248 - Liber Ignium ad Comburendos Hostes, auctore Marco Græco; ou, Traité des Feux propres à détruire les Ennemies, composé par Marcus le Grec. Publié d’après deux manuscrits de la Bibliothèque Nationale. Paris, 1804, three sheets in quarto.].

It contains many recipes, but only with a few variations, as in Albertus Magnus; and it may be evidently seen that Roger Bacon employed this writing, which is mentioned by Jebb in the preface to his edition, from a copy preserved in the library of Dr. Mead. Of this Marcus Græcus nothing at present is known. According to some, he lived in the ninth century; but others, with more probability, place him in the thirteenth. Of his work, perhaps, we have only a translation; for, from the surname Græcus, there is reason to think that the original was written in the Greek language. I must, however, remark that Cardan, where he gives directions for making a fire which can be kindled by water, names Marcus Gracchus, but not Græcus. Scaliger, who, as is very probable, had this writing also, makes no mention of it or its author.

This Marcus speaks of saltpetre three times; first under the name of sal petrosum, which occurs also in the same prescription in Albertus Magnus; but the addition, which Albertus does not repeat, is very remarkable. In my opinion, scrophulæ contra lapides means the incrustation found on walls, which was represented as a kind of leprosy. The addition of ashes, or alkaline salts, the author either forgot or omitted, because perhaps he did not consider it as indispensably necessary. In another place it is said, Lapis qui dicitur petra solis, or, as it is in other manuscripts, salis; but whether saltpetre is here understood I will not venture to determine. In a third passage we find the words de sale petroso, or de salepetro.

In the works of Bacon the term sal petræ occurs at least three times. According to Casiri, the term pulvis nitratus is to be found in an Arabic manuscript, the author of which lived about the year 1249[1249 - Biblioth. Arab. Hisp. Escurial, ii.]. If the work of Geber, already quoted, be genuine, and if this writer lived, as some think, in the eighth century, it would be the oldest where saltpetre is mentioned, in a prescription for an aqua solutiva or dissolutiva, which almost seems to be aqua regia. I have not observed the name sal petræ in the works of Vincent Bellovacensis, who lived in the thirteenth century.

In a word, I am more than ever inclined to accede to the opinion of those who believe that gunpowder was invented in India, and brought by the Saracens from Africa to the Europeans, who however improved the preparation of it, and found out different ways of employing it in war, as well as small arms and cannon[1250 - See the works quoted in Fabricii Bibliograph. Antiquar. p. 978. In the year 1798, M. Langles proved, in a paper read in the French National Institute, that the Arabians obtained a knowledge of gunpowder from the Indians, who had been acquainted with it in the earliest periods. The use of it in war was forbidden in their sacred books, the Veidam or Vede. It was employed in 690 at the battle of Mecca.]. In no country could saltpetre, and the various uses of it, be more easily discovered than in India, where the soil is so rich in nitrous particles that nothing is necessary but to lixiviate it in order to obtain saltpetre; and where this substance is so abundant, that almost all the gunpowder used in the different wars with which the sovereigns of Europe have tormented mankind was made from Indian saltpetre[1251 - The following may be advantageously consulted: – Archæologia, v. p. 148; Henry’s Hist. of Great Britain, vol. iv.; Muratori Antiq. Italiæ Medii Ævi, ii. p. 514; Watson’s Chemical Essays, i. pp. 284, 327; Histoire de France, par Velly, xvi. p. 330; Dow’s Hist. of Hindostan, vol. ii.; Erdbeschreibung der entferntesten Welttheile, ii. p. 159; Stettler Schweitzer Chronik. p. 109. The inhabitants of Berne purchased the first gunpowder from the people of Nuremberg in 1413.]. If it be true that saltpetre was not known in Europe till the thirteenth century, neither gunpowder nor aquafortis could have been made before that time; for the former cannot be prepared without saltpetre, nor the latter without nitre. But if it be true that this salt was known at a much earlier period in India, it is not improbable that both gunpowder and aquafortis were used by the Indians and the Arabians before they were employed by the Europeans, especially as the former were the first teachers of chemistry to the latter. In my opinion, what I have already related proves this in regard to gunpowder; and what I shall here add will afford an equal proof in regard to aquafortis.

It is difficult to discover the first mention of mineral acids in the writings of the ancient chemists. In the course of their numerous experiments they obtained indeed, at an early period, acids, the utility of which they extol; but each concealed the process by which they were made; and as they had no method of obtaining them pure, they were for a long time unacquainted with the difference between the kinds. Their prescriptions, when they are found, are so contradictory and so carelessly written, that it is almost impossible to conjecture which of the known acids forms the principal component parts in their recipes or mixtures.

It appears to me, that the first intelligible account of aquafortis occurs in the writings of the Arabians, or of the pupils of Arabian chemists. At present I am acquainted with none older than that to be found in the works of Geber. For though I do not believe that those of which we have Latin translations belong to a Geber of the eighth or ninth century, I am ready to admit that they may be, at any rate, of the twelfth. This appears probable, because about that period aquafortis and various arts are oftener mentioned, and in a much clearer manner, in these writings.

It is to be regretted in the history of chemistry, that it is impossible to determine the period of the Greek chemist or alchemist known under the name of Synesius; but it cannot be doubted that he borrowed a great deal from the works of the Arabians. This Synesius, among the chemical solvents, mentions water of saltpetre, which might be considered as aquafortis[1252 - A fragment from the writings of Synesius was printed, for the first time, in Frabricii Bibliotheca Græca, viii. p. 236, where the words occur.]. But, as he mentions at the same time aqua fæcis, he appears to me to allude to the nitrum of the ancients, not to our saltpetre, and in general to strong alkaline leys, which indeed are capable of dissolving many bodies.

The monk Theophilus, of whom I have already spoken, and who in all probability lived in the twelfth century, appears also to have been acquainted with aquafortis; for in some of the passages quoted from his works by Raspe[1253 - Raspe on Oil-painting. London, 1781, 4to, p. 145.], he speaks of an acid which dissolved all metals. In the writings of Vincent Bellovacensis, in the thirteenth century, some traces, but very doubtful, are found of aquafortis. Where he mentions the different sorts of gold he speaks of dissolving it, but by this expression he does not allude to its treatment with fire, which he speaks of separately[1254 - Speculum Naturale, vii. cap. 13, p. 432.]. In another place he mentions the different solvents, and among these names vegetable acids, a water of sal-ammoniac, and a water obtained from alum by distillation. He here means undoubtedly a mineral acid[1255 - Lib. vii. cap. 88, p. 480.]. Michael Meier, the most learned chemist of the seventeenth century, says that Vincentius speaks of aquafortis as of a secret; but the passage I have not yet been able to find[1256 - Symbola Aureæ Mensæ. Francof. 1617, 4to, lib. vii. p. 335.].

Spielman states that Lullius, who died in 1315, in the eightieth year of his age, gave an account of his obtaining aquafortis from saltpetre by the addition of vitriol, and that Basilius Valentin was acquainted with the use of clay for the same purpose. Picus Mirandula however declares it to be uncertain whether Arnoldus de Villa Nova was acquainted with the acid of saltpetre in the fourteenth century.

It appears to be an old tradition that this acid was first employed at Venice, by some Germans, for separating the noble metals, and conveyed thence as an article of merchandize to every part of Europe. The persons who prepared it were there narrowly watched, in order that the process might not become known. They were employed chiefly for separating the gold from the Spanish silver, and by these means acquired great riches. Hence arose the report that the people of Venice understood the art of making gold; and it is certain that in many countries the gold refiners were for a long time considered as gold makers; but in no period were there more gold makers than in that when separation in the moist way became known. I can however give less account of this art of the Venetians than of the introduction of it into France in the fifteenth or the beginning of the sixteenth century.

William Budæus, who was born in 1467, and died in 1540, speaks of it in his book, printed for the first time in 1516, as a thing entirely new at that period[1257 - De Asse, 1556, fol. lib. iii. p. 101.]. A man of low extraction, named Le Cointe, first undertook to separate gold from silver at Paris, by means of a water which Budæus calls aqua chrysulca. It is very remarkable, that by means of this water he could separate the smallest particle of gold from silver, and from every other metal; nay, he could even take from vessels their gilding without altering their form. By this art he acquired great wealth; which together with his secret descended to his son, who at the time was the only gold refiner at Paris.

He adds, that the art was exceedingly dangerous as well as unhealthy, and required great precaution. The possessor of it, when he became rich, left the execution of the work to a servant, whom he directed at a distance, that he might not expose himself to the pernicious fumes of the effervescing liquor. The fumes of the acid derived from saltpetre are indeed prejudicial to the health; but the danger has been much exaggerated, and no doubt with a view to deter people from attempting to discover the art, and to furnish a pretence for raising the price of the production[1258 - Les Anciens-Minéralogistes de France, par Gobet. Paris, 1779, 2 vols. 8vo, i. p. xxxiv. i. p. 51, 284; ii. p. 847.].

Budæus relates also, that the gold was left behind undissolved. The silver only was dissolved, and by another art was separated from the water and washed. It may here be easily perceived that Le Cointe employed aquafortis; but if he was able to loosen the gold from gilt vessels without destroying them, he must have used aqua regia, which consequently was not then unknown.

From other information, it appears that the mint at Paris purchased the art from Le Cointe’s son, but still kept it a secret. On this account Francis I., by a decree issued at Blois on the 19th of March 1540, authorized the raising the value of coin, in order to defray the expense of fuel and assaying-water. In the middle of the seventeenth century, the preparation of aquafortis and the process of assaying in the moist way were fully known in France. At any rate, in the month of January 1637, the distillers obtained a guild letter, in which aquafortis is mentioned among the articles sold by them.

When saltpetre became necessary to governments for the manufacture of gunpowder, they endeavoured to obtain it at as cheap a rate as possible. No one before suspected that rulers would be justified in exclusively carrying away the incrustation of walls from private houses, which, when it could be used, became accessorium fundi. But the idea of regalia, so often abused, was extended so wide under various pretences, that the saltpetre regale and the letting of it was one of the severest oppressions to which the people were exposed by their rulers, and which occasioned almost as bitter complaints as the hunting regale, founded on no better grounds. I shall not here attempt to delineate the sufferings which were thus occasioned in many countries; they are still fresh in remembrance.

The oldest mention of this hated regale which I myself have found is of the year 1419. At that time, Gunther, archbishop of Magdeburg, granted to some person the right of searching out saltpetre and boiling it, during a year, in the district of Gibichenstein, for which he was to pay a barrel of saltpetre, and deliver to the archbishop the remainder at the rate of five cross-groschens per pound. The succeeding archbishop, Frederick, let in the year 1460, to a burgher of Halle, all the earth and the saltpetre that could be collected from it in the bailiwick of Gibichenstein, for four years, at the annual rent of a barrel of good refined saltpetre. On the same conditions, bishop Ernest, in 1477, let to some one for his lifetime the collection of the saltpetre. In 1544, a certain person obtained the collection of saltpetre from two heaps of rubbish before the gates at Halle. The magistrates of Halle also in 1545 had a saltpetre-work and a powder-mill. In the year 1560, John VI., archbishop of Triers, gave to some one permission to search for and dig up saltpetre. In 1583, the saltpetre regale was confirmed by a Brandenburg decree as a thing long known, and the case was the same with a Hessian of the year 1589.