The experiment, showing the formation of sal ammoniac by a direct union of its component parts, may be made by bringing in contact, in a glass receiver, muriatic acid gas and ammoniacal gas. White clouds will form, a condensation take place, and muriate of ammonia be deposited on the sides of the vessel.
Sal ammoniac was altogether made, at one period, from the soot of camels' dung, or of other animals, which feed on saline plants. The excrement was burnt, the soot collected, and sublimed. This was the process practised in Egypt. The composition of sal ammoniac being known, the process for obtaining it was improved; so that, instead of using the soot of dung, it is now formed by the distillation of bones. The impure ammoniacal liquor, thus obtained, is combined with sulphuric acid, by an easy process, and the resulting sulphate of ammonia is then decomposed by muriate of soda, by which sulphate of soda and muriate of ammonia are produced. They are separated, and the latter is formed into heads by sublimation. In this state, it occurs in commerce. It was made in great quantity in the vicinity of the temple of Jupiter Ammon; and hence its name.
Mr. Minish, according to the English writers, is entitled to this method of converting impure liquid ammonia into sal ammoniac. The following is an outline of his process. He suffered the impure ammoniacal liquor to percolate through a stratum of bruised gypsum, and as carbonate of ammonia is contained in the liquor, the fluid, which filters, would contain sulphate of ammonia, the carbonate of lime being insoluble. This sulphate he evaporated, and the dry mass, mixed with muriate of soda, was sublimed. If I am not greatly mistaken, however, although I have not the work to refer to, this process is described in Dr. John Pennington's Chemical Essays, a work published in Philadelphia, about 1792. Dr. Pennington's work, we may observe, is the first chemical book which was published in the United States, and contains numerous important facts and observations. That this process was known in Philadelphia, and used at the Globe works, or rather Glaub works, (from the circumstance that Glauber's salt was made there,) is within the recollection of many. I heard the late professor Wistar speak of this process, and of the economy in using gypsum.
Mr. Lebanc (Annales de Chimie, vol. XIX.) invented a process, by which he brought the ammoniacal gas and muriatic acid gas in contact, in a chamber lined with lead. In one pot, he put common salt and oil of vitriol; in another pot, animal matter. Being conducted by pipes into the chamber, the gases united, and sal ammoniac was formed. Other improvements have been made, as obtaining ammonia from coal soot, &c.
Ammonia is generated in artificial nitre beds, and is at first united with nitric acid; which compound is subsequently decomposed, as the process of putrefaction goes on, by the potassa, calcareous earth, &c. present in nitre beds. See [Nitrate of Potassa.]
Sal ammoniac is ready formed in the soot of animal feces, twenty-six pounds of which yield six of the salt. According to Siccard, who published, in 1716, an account of the fabrication of sal ammoniac in Egypt, which Geoffroy, in the same year, proved to be a compound of the spirit of sea salt and volatile alkali, sea salt and urine were used in that country. The account, however, given by Lemery, in 1719, makes no mention of either sea salt or urine.
Sal ammoniac is found native. It occurs in the vicinity of burning beds of coal, both in Scotland and England, and is met with in volcanic countries. When triturated with quicklime, it exhales ammonia, which is a characteristic of all ammoniacal salts.
Sal ammoniac is often found in crusts of lava. Sir William Hamilton observes, that, in the fissures formed by the lava, this salt sublimes. He found, in the same locality, common salt.
Sal ammoniac is decomposed by a variety of substances. Sulphuric acid will disengage the muriatic acid from it, while lime, potassa, &c. liberates the ammoniacal gas, which, when combined with water by distillation or other means, forms the common spirit of sal ammoniac, or water of ammonia. Mixed with carbonate of lime and sublimed, it produces the carbonate of ammonia, usually called mild volatile alkali, or pungent smelling salts. Ammonia, in a separate state, unites with some metallic oxides, giving rise to certain fulminating powders, which have been already noticed. That iodine decomposes ammonia, we have shown, when on the preparation of iodide of azote, or fulminating powder.
Sal ammoniac enters into the composition of candles, to prolong their duration. The process recommended in the Archives des Découvertes is the following: Dissolve, in half a pint of water, a quarter of an ounce of sal ammoniac, two ounces of common salt, and half an ounce of saltpetre, and add the solution to three pounds of mutton tallow, and eight pounds of beef tallow, previously melted. Continue the heat until all the water is evaporated. It is then suffered to cool, and, when used, is to be melted with a quarter of an ounce of nitre, and formed into candles in the usual manner. This preparation of tallow is highly recommended on account of its economy, as well as the improvement itself. A candle, made of this tallow, will burn two hours longer than one of the ordinary kind.