Herodotus, Strabo, Arrian, and others, speak of rock-salt which was dug up in Ammonia, and carried thence as an article of merchandise. The first mentions a hill of salt; and we are told by the last, that native salt was brought to Egypt as a present to the king and others, from the neighbourhood of the oracle of Ammon, by the priests of that place, in boxes made of palms worked together. Many pieces were three inches in length; and because this substance was purer than bay salt, and as clear as crystal, it was particularly employed in sacrifices. This salt is certainly that which, under the name of sal-ammoniacus, was sent from Egypt to the king of Persia, like the water of the Nile, as is related by Athenæus from an historian long since lost[978].
It is also certain that the old Arabian physicians, Avicenna and Serapion, who both lived in the eleventh century, under the name sal-ammoniacus understood nothing else than rock-salt. The former says that it ought to split easily, and to be clear and transparent like crystal; and the latter states that this salt is cut from the solid rock, and that it is sometimes clear as crystal, sometimes reddish, sometimes blackish, sometimes of another colour, sometimes hard, and sometimes friable, or, as the translator expresses it, pulverulent. All these colours and properties are not uncommon in rock-salt, and always proceed, no doubt, from an admixture of ferruginous earth. Serapion says that this salt was obtained from Corasini. I shall leave it to others to determine where this country was situated. He often names it, and says that mala granata and bezaar were obtained from it. But who knows how the name was written in the original? And the Arabian author perhaps did not mention the place where the salt was dug up, but that from which, in his time, it was procured[979].
In regard to the purpose to which the ancients applied their sal-ammoniacus, it appears that it required only common salt and not sal-ammoniac. It is oftenest mentioned by the physicians, because it was the purest table salt that could then be procured. On that account it has been praised by Scribonius Largus, who lived in the first century, and by Aetius who lived in the fifth, as well as by Avicenna, Serapion, and others. I have however not yet met with it in the writings of Hippocrates or Galen. In the works of the Greek agriculturists it occurs in a recipe for the preparation of a cement employed to close up wine vessels[980]. According to a recipe of Apicius, in his book on cookery, sal-ammoniacus was to be roasted. By these means this rock-salt lost its water of crystallization and became stronger. On this account, in Transylvania, Siberia, and other countries, before it is brought to the table it is pounded and roasted. Of our sal-ammoniac, however, were it roasted, very little would remain. But whether the ammonium which Palladius recommends for a cement[981] be that salt, I will not pretend to determine. On the other hand, I have no hesitation to contradict the old commentator on Ovid, who, in a passage where the poet recommends sal-ammoniacus in making a cosmetic water, understands the resin or gum of that name. Ovid however had no intention that young women should lacker themselves.
For the reasons therefore already mentioned, I am convinced that the sal-ammoniacus of the ancients was rock-salt, and not our sal-ammoniac. The oldest commentators also on these writers had no idea of any other than rock-salt; and it was not till a later period, when our sal-ammoniac was introduced into commerce, and acquired that name, that the most learned commentators began expressly to remark, that the new sal-ammoniac, notwithstanding its appellation, was different from the sal-ammoniacus of the ancients. As this could not then be obtained, people used the former, which they considered only as an artificial substitute for the latter, though it was incapable of supplying its place. But in more modern times, when our sal-ammoniac became common, and physicians and mineralogists no longer took the trouble to read the works of the ancients, some of them, if not the greater part, spoke in such a manner as if our sal-ammoniac had been the sal-ammoniacus of the ancients; and it was then generally believed that it had been, at any rate, known and used since the time of Dioscorides and Pliny.
No one has maintained this with greater confidence and zeal than F. I. W. Schröder[982], whose judgement however was perverted by alchemistic conceits. According to his assertion, the Egyptians practised from the earliest periods the art of making sal-ammoniac, but they kept it a secret; and he obscurely hints at the purpose for which these great chemists used so much salt. He refers, on this occasion, to what Pliny says of flos salis[983], in which he thinks he can find the martial sal-ammoniac[984] flowers of our chemists, or the so-called flores salis ammoniaci martiales. Those who cannot make this discovery he declares to be ignorant and blind. This decision, however, when the character of the person who gives it is considered, cannot dissipate a single doubt. It is certain that what Dioscorides and Pliny call flos salis has never yet been defined. It was moist, oily, and saline; and in the vessels, in which it was sent from Egypt, was grey at the top, saffron-coloured at the bottom, and emitted a bad smell. The most ingenious conjecture was that of Cordus[985], who thought that it might be sperma ceti; but though I should prefer this opinion to that of Schröder, I must confess that, on the grounds adduced by Matthioli and Conrad Gesner, it has too much against it to be admitted as truth.
The first distinct traces of our sal-ammoniac which I have yet met with are to be found in the works of the Arabians[986]. In a writing of Geber, there is a prescription how to purify sal-ammoniac by sublimation, and in another a receipt for making it; so that there can be no doubt that the author was acquainted with our salt. But this furnishes very little towards the history of it. The period when that celebrated chemist lived is uncertain. If, as Leo says[987], he flourished a hundred years after Mahomet, that is to say in the eighth century, his works must have been interpolated with many additions, which criticism has not yet been able to separate. Many of them cannot be of great antiquity; and the uncertainty is increased by some of the editions differing from each other in important passages. Whole sections, which some have, are wanting in others; and the titles and order of the books and sections are different almost in each. When the same circumstances are found in several editions, it is observed that they essentially differ. What, therefore, is now found in the writings of Geber, as they are called, was certainly not all known in the eighth century.
The same uncertainty prevails in regard to the chemical works of Avicenna, who lived in the beginning of the eleventh century, and who certainly treats of sal-ammoniac. But when these are compared with the medical works of this author, which are subject to no doubt, it is evidently perceived that the former must have been the production of a very different and much younger writer. In the works of the physician Avicenna, sal-ammoniacus means always rock-salt. It is worthy of remark, that Avicenna the chemist says, that sal-ammoniac comes from Egypt, India, and Forperia.
We know with more certainty that Albucasis, or Bulcasis, was acquainted with sal-ammoniac, as well as the method of preparing it, which he describes, and also the preparation of medicines in general, in his book often printed under the title of Liber servitoris[988]. However unintelligible the translation often is, one can easily discover in what manner sublimation was formerly performed in earthen vessels. But the period when this Arabian writer lived is doubtful, though it is generally admitted that he died in the year 1122.
But whence did Europe obtain this salt, in the twelfth and succeeding centuries? When and in what manner was the preparation of it found out in Egypt? For what purpose was it first used by our ancestors? I have not yet met with any information to enable me to answer these questions, though it is probable that it might be found in old books of travels, and particularly in the works of Arabian writers. In the valuable but not altogether intelligible book of Pegolotti[989], from which I have learned many things respecting the trade of the fourteenth and fifteenth centuries, nothing is said in regard to the place where it was obtained, but that it was procured in white, hard, and opake cakes. It is mentioned in the custom-house tariff of Pisa for the year 1408.
Biringoccio, who lived in the end of the fifteenth and beginning of the following century[990], knew nothing more than that, according to report, it came from Cyrene or Armenia. Cæsalpin, his contemporary, gave, for the preparation of it, a prescription which is undoubtedly borrowed from the Arabians. This author says, very properly, that it is obtained in white transparent cakes, blackish on the outside; but adds, erroneously, that it comes from Germany, though the same thing has been repeated by Brasavolus and Matthioli. Porta says, with more truth, that it comes from the East. He asserts also, that he was the first person who found real sal-ammoniac on volcanic mountains, and he wishes that his discovery might be confirmed by skilful naturalists[991]. This may serve as an additional proof, were such necessary, in opposition to those who think that the first real sal-ammoniac introduced into commerce was the volcanic. Imperato considers Porta’s observation as generally acknowledged, but without naming him. The former has described, in a fuller and more correct manner than any of his predecessors, the properties of sal-ammoniac[992]; and he states, as does also Agricola[993], that it is entirely dissipated in the fire. He adds, that it promotes the production of a celestial blue colour, and in all probability he here alludes to a solution of copper.