Without attempting to examine at what time the art was discovered of converting the nitric acid into aqua regia by the addition of sal-ammoniac, I shall only remark that, at any rate, it was known in the sixteenth century; for Imperato says that sal-ammoniac is employed in the solution of gold; and Biringoccio[994], who is older, recommends nitrous acid prepared with sal-ammoniac for dissolving metals, and particularly gold. I will not either determine how old the use of this salt is in soldering and tinning; but I must observe, that it was known to Agricola[995] and Imperato. I however doubt whether it was very common, because Biringoccio[996] recommends borax for that purpose, without so much as mentioning sal-ammoniac; though it is possible that I may have overlooked it.
We are now arrived at the modern history, which I shall give in as brief a manner as I can, because it has been already fully treated on by others. What was long ago shown by the celebrated Mr. Boyle was proved in the year 1716 by Geoffroy the younger, that sal-ammoniac was composed of the muriatic acid and volatile alkali, and that it could be thence prepared in Europe by sublimation[997]. In the same year the jesuit Sicard gave the first certain account of the sal-ammoniac manufactories at Damayer, in the Delta, and described in what manner this salt was prepared there, by sublimation in glass vessels, from the soot of the burnt dung of camels and cows, which is used in Egypt for fuel, with the addition of sea salt and urine[998]. In the year 1719, the Academy of Sciences at Paris received from Lemere, the French consul at Cairo, an account of the process employed; but it contained no mention either of sea salt or of urine[999]. Afterwards this information was in part confirmed, and in part rectified and enlarged, by Paul Lucas[1000], Granger, or, as he was properly called, Tourtechot[1001], and the celebrated travellers Shaw, Pocock, Norden, Hasselquist, Niebuhr, and Mariti.
Several writers have asserted that sal-ammoniac comes also from the East Indies. It is mentioned by Tavernier among the wares which in his time were brought from Amadabat, in the territories of the Mogul, to Surat; and Geoffroy states, that when the trade of Marseilles was interrupted by the plague, the French obtained from Holland sal-ammoniac, which was shaped like a truncated cone, and was given out to be Indian[1002]. Pomet also says, that some of the same kind was formerly procured from Venice and Holland. But Gaubius asserts that he was never able to hear of any such sal-ammoniac in Holland[1003]; nor is it to be found in the price currents of the East India Company. I am almost inclined to suspect that these truncated cones were formed by the merchants from broken pieces or fragments of the Egyptian sal-ammoniac, by solution and imperfect crystallization or sublimation. In this manner the merchants at Marseilles convert the refuse of the Egyptian sal-ammoniac into cakes by a new sublimation, in order that it may become more saleable, though it is not readily purchased by artists. Gaubius, however, has described a kind of sal-ammoniac which he obtained from India, with the information that it was made in Hindostan from the soot of animal dung; but in my opinion this requires further confirmation[1004].
Where and at what time the first works for making sal-ammoniac were established in Europe, I am not able to determine. The account given by Thurneisser, that the first sal-ammoniac was made in the Tyrol in the ninth century, is truly ridiculous. It is not worth the trouble to inquire where he or Paracelsus found this foolish assertion. One might be almost induced to believe, that in the time of Boyle there were manufactories of sal-ammoniac in Europe[1005]. But perhaps there may be no other foundation for all this than the before-mentioned assertion of Cæsalpinus, that this salt came from Germany. At Bamberg, the Germans were long accustomed to boil the sediment of the salt-pans with old urine, and to sell it cheap for sal-ammoniac; and Weber asserts that some of the same kind is still made at Vienna. The hundred weight costs from twenty to thirty florins, but the refuse may be purchased for a mere trifle. If I am not mistaken, the first real manufactories of sal-ammoniac were established in Scotland; and the oldest of these, perhaps, was that erected by Dovin and Hutton at Edinburgh in 1756, and which, like many in England, manufactures this salt on a large scale[1006]. Among the later undertakings of this kind is Gravenhorst’s manufactory at Brunswick, and that which in the neighbourhood of Gothenburg manufactures sal-ammoniac from the refuse left in making train oil.
[Sal-ammoniac is now prepared either by the destructive distillation of bones or coal. The gas-liquor supplies, we believe, the largest part. This fluid contains hydrosulphuret and carbonate with some other salts of ammonia. It is decomposed with sulphuric acid, and on evaporation the sulphate of ammonia is obtained in a crystalline state. This is then mixed with common salt and the mixture heated in iron vessels, whereupon the muriate of ammonia sublimes.
Sal-ammoniac is exported in considerable quantities to Russia and other parts of the continent and to the United States.]
FOOTNOTES
[972] It is indeed a matter of indifference whether the name be derived from αμμος, arena, or rather from Ammonia, the name of a district in Libya, where the oracle of Jupiter Ammon was situated. The district had its name from sand. An H also may be prefixed to the word. See Vossii Etymol. p. 24. But sal-armoniacus, armeniacus, sal-armoniac, is improper.
[973] De Re Rust. vi. 17, 7.
[974] Lib. xxxi. cap. 7, sect. 39.