time behind their neighbours in this improvementin cookery, as it is not mentioned by Colerus, Florinus, and Heresbach. Hohberg* only speaks of it as a thing usual in France. It is not improbable that some of the French, driven from their native country by the revocation of the edict of Nantes, may have introduced it into Germany; and perhaps the well-known Von Eckhart† was the first who, in 1753, gave a complete description of this art to my countrymen, and rendered it clear by a wood-cut. He employs, on this occasion, the new-fashioned term poularderie, and says, that it was first known in the German courts, to which it was brought from France.

SALTPETRE. GUNPOWDER. AQUAFORTIS.

IN examining the question, whether Theophrastus, Pliny, and in general the ancient Greeks and Romans, were acquainted with our saltpetre, or at what period it became known, I shall perhaps meet with as little success as those who have pre

• Georgica curiosa. Nuremberg 1716. fol. ii. p. 377.

+ Experimental-Oekonomie. Jena 1754, 4to. p. 325. According to Suckow's edition, p. 326.

ceded me in the same research.* I shall therefore be satisfied if competent judges allow that I have contributed any thing new that can tend to illustrate the subject.

Our saltpetre, which is commonly called nitrum, and sometimes, though more rarely, sal nitræ, is a neutral salt from the acid peculiar to it, named the acid of saltpetre, and that vegetable alkali to which our pot-ash in general belongs. The marks by which it is most readily distinguished from the other salts are its cooling taste; its fusibility when exposed to a small degree of heat, and in par ticular, its so called decrepitation; that is, the

To this subject belong the following works: Ars magna artil leriæ, auctore Casim. Siemienowicz. Amst. 1650. fol. p. 61. The author thinks that the nitrum of the ancients is not at present known.

The Natural History of Nitre, by Will. Clarke. Lond. 1670. 8vo. Naturalis Historia Nitri. Francof. et Hamb. 1675, 8vo, p. 19. It is here said that the nitrum of the ancients was impure saltpetre, and that the latter is produced from the former by purification. The Latin translation is, in many parts, unintelligible.

G. C. Schelhameri de nitro, cum veterum tum nostro, commentatio, Amst. 1709, 8vo, contains good philological observations, particularly in regard to the period, but leaves the question undeter mined.

Saggi sul ristabilimento dell' antica arte de' Greci e Romani pittori, del Sig. Doct. Vincenzo Requeno, Seconda ediz. Parma 1787, 2 tomi in 8vo. ii. p. 95 and p. 131: a learned work, but spun out to such a length, that it requires some trouble to discover the author's meaning, and the grounds on which it is supported. He thinks that the nitrum of the ancients was our saltpetre; and what others consider as proofs of its being mineralised alkali, he understands as indicating

property it has when placed in the fire, or on an ignited body, or when melted in a crucible with an inflammable substance, of suddenly bursting into a very bright flame, by which it becomes alkalised, or in other words loses its acid, so that nothing remains but the vegetable alkali. The principal use of it is in making gunpowder, and for the preparation of that acid known under the name of aqua-fortis, which is employed in various ways.

Native saltpetre, or saltpetre completely formed by nature, is so rare, that Cronstedt was not acquainted with it. At present, however, it is known that it is found in the East Indies, in the lower

alkalised saltpetre. I am not, however, convinced. Before I ascribe to the ancients a knowledge of our saltpetre, I must be shown in their writings properties of their nitrum sufficient to convince me that it was the same substance, that is to say, properties not belonging to alkali, but to our saltpetre alone. It is to be observed also, that this Italian author is not always correct in quoting his sources.

Commentat. de nitro Plinii, in J. D. Michaelis commentationes, Bremæ 1784, 4to. The author only illustrates the account of Pliny, and states what, according to his opinion, we are to understand in it in regard to alkali, and what in regard to our saltpetre. When this dissertation was about to be printed the second time, the author requested from me some annotations; which, however, I did not give, because they must have opposed his assertions. I was unwilling to offend either my pupils or friends, by contradicting a circumstance which could have no influence on human happiness.

In Tromsdorfs Journal der Pharmacie, iv. 1. p. 129, professor Fuchs says, he had sent a dissertation on the natrum of the ancients to the Electoral Academy of Mentz, which however I do not find in their Transactions.

part of Italy, also in Portugal,* Spain,† America, and some other countries. § But almost all the saltpetre obtained in Europe is produced partly by nature and partly by art. The putrefaction of organised bodies gives rise, under certain circumstances, to nitrous acid, which in general combines with calcareous earth wherever it finds it, and forms the so called earthy saltpetre. This is decomposed by fixed vegetable alkali, and the latter uniting with the acid forms common saltpetre. Sometimes also it is found that the nitrous acid, instead of being united with calcareous earth, is united with the mineral alkali, which produces the so called cubical saltpetre.

I found the account of the Portuguese saltpetre in Mémoires instructifs pour un voyageur, a translation of which was published at Dantzic, 1755, 8vo, with the following title: Der gegenwartige staat von England, Portugal, und Spanien, i. p. 177. The author of this work was the well-known Theodore king of Corsica.

The proofs, in regard to Spanish saltpetre, may be found in my Physikal-Econom. Bibliothek, xi. p. 508. xiv. p. 122. xviii. p. 189.

A description of Patagonia, by Faulkner. Herford 1774, 4to. § More accounts of native saltpetre may be found in Recueil de mémoires sur la formation du salpetre. Par les commissaires de l'Academie. Paris 1776, 8vo. Del nitro minerale memoria dell' ab. Fortis, 1787, 8vo.

The first, or one of the first, who was acquainted with and made known the cubical saltpetre, was professor John Bohn of Leipsic, in the Acta eruditorum, 1683, p. 410; but with more precision in his Dissertat. chymico-physicæ, Lips. 1696, 8vo. p. 36: Inter alios aquam regiam parandi modos hic pluribus innotescit, ut spiritus nitri a sale communi cohobetur, sicque aliquid de spiritu

Both these saline substances, but the earthy more frequently than the cubical, are often found on effloresced walls; and both are then comprehended under the common names of mauersalz or mauerbeschlag, sal murale.

This efflorescence on walls was observed, in all probability, at a very early period, especially as it is produced in many parts in great abundance, and as it makes itself perceptible by the decay of walls, which it seems to corrode. It is the plague or leprosy of houses mentioned in the Mosaic code of laws.* As the ancients were so much inclined to expect medicinal virtue in all natural bodies, there is reason to think that they soon collected and made trial of this saline incrustation. That this indeed was actually the case, and that they gave the name of nitrum to this saline mass, may be proved from their writings. Their nitrum, however, must have been exceedingly various in its properties. For this incrustation is not always calcareous saltpetre; it is often mineral alkali, to which, at present, chemists rather give the am

salis recipiendo virtutem aurum solvendi acquirat, potentiam in argentum perdat; pauci vero profecto attenderunt, parum hoc menstraum amplius de spiritu nitri, plus autem longe de salis stagmate, participare; quippe sal in fundo retortæ remanens, si crystallisetur, figuram quidem salis cubicam præ se fert, quantum quantum tamen est, nitrum evasit, quod ejus inflammabilitas, sapor, ac spiritus inde elicere jubent.

• Levit. chap. xiv. ver. 33. See J. D. Michaelis Mosaisches Recht. Frankf. 1778, 8vo. Theil iv. p. 280.