should not be greater than about 200° Fahr., and need not exceed 150° to 155°. These pots are arranged in sets, as shown at D in the engraving.
The charge of a retort usually consists of about 70 to 72 lbs. of sulphate of ammonia or 57 to 58 lbs. of the hydrochlorate to 1 cwt. of chalk; or in these proportions. The product is about 40 lbs. of the crude salt, which, by careful resublimation, yields about 39 lbs. of marketable carbonate of ammonia.
Carbonate of ammonia, like the chloride and sulphate, is now scarcely ever prepared on the small scale, that of commerce being not only cheaper, but sufficiently pure for all the purposes of medicine and the arts.
Ammonium, Bicarbonate of. HNH4CO3. Prep. By digesting cold water on sesquicarbonate of ammonia in considerable excess, until the whole of the pungent neutral carbonate is dissolved out. If the salt is reduced to powder the operation is facilitated.
To powdered sesquicarbonate of ammonia add boiling water just sufficient to dissolve it, and immediately close the vessel; crystals form as the liquid cools, containing 21⁄2 equiv. of water.
Prop., &c. For the most part similar to the sesquicarbonate, except in having a taste and smell which is only faintly ammoniacal, and hence more palatable. Crystallises in oblique prisms, which, as usually obtained, contain about 23% of water. It requires 8 parts of cold water to dissolve it. It is distinguished from the previous carbonates by the almost entire absence of ammoniacal odour, and by its solution giving no immediate precipitate with chloride of barium, but by standing, or on the addition of a little liquor of ammonia, a white earthy precipitate, accompanied with the evolution of carbonic acid gas. A saturated solution of this salt, evaporated by a very gentle heat, or refrigerated, gives small prismatic crystals having neither smell nor taste.
Uses, &c. Similar to those of the other carbonates.—Dose, 6 or 7 to 20 or 25 gr.
Ammonium, Chloride of. NH4Cl. Syn. Muriate of ammonia, Sal ammoniac, Hydrochlorate of ammonia; Chlorohydrate d’ammoniaque, Sel ammoniac, &c., Fr.; Salmiak, Ger. A substance which, as already noticed, appears to have been originally obtained, by sublimation, from the soot of camels’ dung, in Egypt. In this country, at the present day, it is manufactured chiefly from the crude ammoniacal liquors obtained as secondary products in the manufacture of coal-gas and animal charcoal.
Prep. 1. From GAS-LIQUOR:—The crude ammoniacal liquor of the gas-works is, either at once, or after distillation,[48] neutralised with hydrochloric or sulphuric acid, the choice being given to the one which is the cheaper and more accessible at the place where the works are situated. When hydrochloric acid is employed, the SATURATION is usually effected by allowing the acid to flow from a large wooden vessel or tank lined with lead or gutta percha into a large underground reservoir or tank containing the ammoniacal liquor, and having an exit-tube passing into the chimney or shaft of the steam-engine, to carry off the sulphuretted hydrogen and other offensive gases liberated during the mixture. Sometimes the gas-liquor is accumulated in enormous covered wooden tuns, capable of holding from 10,000 to 20,000 gallons, or more; and the acid is added by raising the gutta-percha carboys containing it by means of cranes, and then thoroughly mixing it with the liquor by means of powerful ‘agitators,’ whilst the offensive fumes are either passed off as before, or made to traverse the fire of the steam-engine before entering the chimney-shaft. The quantity of acid employed to effect saturation must, of course, depend on the ammoniacal strength of the gas-liquor operated on. The usual proportions are 11⁄2 to 2 lbs. of the former, to each gal. of the latter; but in all cases sufficient should be added to impart a very faint acid reaction to the mixture. This last having been effected, the saline