Elements of the Theory and Practice of Chymistry, 5th ed.

by Pierre Joseph Macquer

The action of Fixed Alkalis upon Sal Ammoniac is so vigorous and sudden, that, as soon as these two matters are mixed together, the Volatile urinous Salt rushes out with great activity, even without the help of heat; so that much of it will be lost, if care be not taken to confine the mixture immediately in those vessels by means of which it is to be distilled.

The Volatile Salt obtained by this operation is white, pure, and very active; having been freed from the greatest part of its superfluous fat matter, both by the union it had contracted with the Marine Acid, and by the Fixed Alkali employed to separate it therefrom. This Salt is so quick and volatile, that if, on taking out the receiver, it be left a little too long exposed to the air, before it be put into the bottle in which it is to be kept, a great deal of it will exhale and be lost. For the same reason care should be taken, while the vessels are unluting, that the vapour of this Salt do not strike the organ of smelling, or be drawn into the lungs in respiration; for it affects those organs so powerfully, and makes such a quick impression on them, that the operator would be in danger of suffocation. Yet it is of great service, when cautiously smelled to, for exciting the vibrations of the Genus Nervosum, in Apoplexies, Fainting fits, and Hysterical disorders. But it must always be administered with great caution; for it hath a corrosive quality, and is no less caustic than a Fixed Alkali. This is proved by applying it to the bare skin, and keeping it on by means of a pitch-plaster, so that it cannot fly off in vapours: for, as soon as it begins to grow warm, it produces on the skin a smarting sensation, like that of burning, attended with much pain, and in a very short time makes an eschar like a caustic.

The Volatile Spirit, obtained in the decomposition of Sal Ammoniac by a Fixed Alkali, derives its origin from the Phlegm contained in the saline matters that are mixed together on that occasion. The moister those matters are, the more Spirit there will be. This also is very active and penetrating. But as it owes these qualities wholly to the Volatile Salt dissolved in it, the more of this Spirit comes off, the less Salt will there be.

If you desire to have much Volatile Spirit, a quantity of water, proportioned to the quantity of Spirit you want, must be mixed with the Salts. In this case the distillation begins with a humid vapour, which coagulates on the sides of the receiver into a concrete Salt, almost as soon as it comes over. There rises afterwards an aqueous vapour, not so saline or volatile as the former. This liquor dissolves the Salt that was coagulated before; and, if the water added was in sufficient quantity, it will dissolve the Salt entirely; otherwise it will dissolve but a part thereof, and then it is certain that the liquor is a Volatile Spirit as strongly impregnated with Salt as it can be. The reason why the liquor that rises first contains a great deal more Volatile Salt than the other, in so much that it coagulates and becomes solid, is because the Volatile Salt rises in distillation much more easily than water.

In whatever manner the Volatile Spirit or Salt be distilled from Sal Ammoniac, by means of a Fixed Alkali, we always find at the bottom of the retort, or cucurbit, when the operation is finished, a new Neutral Salt compounded of the Acid of the Sal Ammoniac, and of the Alkali used in the distillation. If the Salt of Tartar be used, this new Neutral Salt will be perfectly like that produced by combining this Alkali with the Acid of Sea-salt, to the point of saturation. The figure of the crystals of this Salt, though much like that of the crystals of Sea-salt, is nevertheless a little different. However, this Salt possesses the chief properties of Sea-salt. It bears the name of Sal Febrifugum Sylvii, because that Physician attributed to it the virtue of curing intermitting fevers. But its title to this virtue is very doubtful, at least in this country.

If the Salt of Soda be used, instead of Salt of Tartar, to decompound Sal Ammoniac, a Volatile Spirit and Salt will in like manner be obtained; and the Neutral Salt left in the retort, after distillation, will be a true regenerated Sea-salt, perfectly like native Sea-salt; because, as we have said before, the Salt of Soda is of the same kind with the natural basis of Sea-salt; and the inconsiderable differences, observable between the Sal Febrifugum and Sea-salt, can be attributed only to such as may be found between the Alkaline bases of those two Salts.

PROCESS V.

Sal Ammoniac decompounded by Absorbent Earths and Lime. The Volatile Spirit of Sal Ammoniac. Fixed Sal Ammoniac. Oil of Lime.

Let one part of Sal Ammoniac, and three parts of Lime, slaked in the air, be pulverized separately, and expeditiously mixed together. Put this mixture immediately into a glass retort, so large that half of it may remain empty. Apply thereto a capacious receiver, with a small hole in it to give vent to the vapours, if needful. Let your retort stand in the furnace about a quarter of an hour, without any fire under it. While it stands thus, a great quantity of invisible vapours will rise, condense into drops, and form a liquor in the receiver. Then put two or three live coals in your furnace, and gradually increase the fire till no more liquor will rise. Now unlute your vessels, taking all possible care to avoid the vapours, and quickly pour the liquor out of the receiver into a bottle, which you must stop with a crystal stopple rubbed with emery. There will remain, at the bottom of the retort, a white mass, consisting of the Lime employed in the distillation, together with the Acid of the Sal Ammoniac: this is called Fixed Sal Ammoniac.