This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
Solutions of ammonia gas in water, the former containing 32.5 per cent. and being about one-third stronger than the simple liquor; they are commonly called "spirits of hartshorn," because formerly prepared by heating scrapings of horns and hides.
By heating sal-ammoniac with slaked lime, and distilling, the gas being passed through wash bottles into a receiver containing water.
CaH1O2 + 2NH1C1 = CaCl2 + 2H1O + 2NH3
The stronger solution is colorless, of sp. gr. .891 to .900, of characteristic pungent odor and alkaline reaction. A piece of moist red litmus paper held in the neck of the bottle is at once turned blue. The tests for its purity are - When diluted with four times its volume of water, it gives no color or precipitate (a) with lime water, showing the absence of carbonic acid; or (b) with oxalate of ammonia, showing the absence of lime; or (c) with sulphide of ammonium, proving its freedom from lead, copper, and other metals; or (d) with ammonio-sulphate of copper, showing its freedom from sulphuretted hydrogen. (e) When rendered acid by excess of nitric acid it gives no precipitate with nitrate of silver or chloride of barium, showing its freedom from chlorides, bromides, iodides, cyanides, phosphates, and sulphates.
The properties of liquor ammoniae are similar, but weaker in degree.