_Prop._ Crystals, long, flattened, six-sided prisms; soluble in 2 parts of cold, and 1 of boiling water; fuses, with loss of one atom of water, at about 280° Fahr.; and is volatilised, with entire decomposition, at about 535°. Even its solution, by long boiling, becomes acid from loss of ammonia. The anhydrous salt does not exist. _Uses, &c._ Pure sulphate of ammonia is diuretic, aperient, resolvent, and stimulant.——_Dose_, 10 to 30 gr. It is now seldom employed in medicine. The crude sulphate is principally used in the preparation of sal ammoniac and sesquicarbonate of ammonia, and for manure. “A mixture of 10% of this sulphate with 20% of bone-dust, some gypsum, and farm-yard manure, forms a very fertilising compost, applicable to a great variety of soils” (Ure); and we may add——greatly superior to a very large portion of what is now so commonly vended under the name of ‘guano.’ _Concluding remarks, Patents, &c._ The manufacture of sulphate of ammonia, on the large scale, has been unavoidably explained in treating on the salts of that base already noticed. All that is necessary is to saturate with sulphuric acid the solution of ammonia, crude or otherwise, and obtained in any manner; and then to evaporate the solution until the salt crystallises out. At other times, however, instead of adding the acid to the ammoniacal liquor, the latter, either at once, or after treatment with lime, is submitted to distillation, and the evolved alkaline vapour is passed into the acid (previously somewhat diluted), contained in a large receiver or cistern, or a series of them; the salt being obtained from the resulting solution in the usual manner. By re-solution and a second crystallisation the sulphate is generally obtained sufficiently pure for all commercial purposes; but when the salt is intended for use as manure, or (unless very rough) for conversion into sal ammoniac, this need not be had recourse to. Among modifications and improvements, not previously noticed, may be mentioned—— 1. That of Dr Richardson (Patent dated Jan., 1850), who mixes SULPHATE OF MAGNESIA with the crude ammoniacal liquor, and thus forms a double sulphate of magnesia and ammonia, from which he obtains the SULPHATE OF AMMONIA by sublimation. 2. That of Michiel (Patent dated April, 1850), who prepares sulphate of ammonia by means of OXYSULPHATE OF LEAD obtained by roasting galena (sulphide of lead), by exposing it in a crushed state and thin layers for 2 or 3 hours, to the heat of a reverberatory furnace. The resulting mixture of sulphate and oxide of lead is reduced to the state of coarse powder, and well worked up with the ammoniacal liquor, when SULPHATE OF AMMONIA and sulphide and carbonate of lead are produced by the mutual reaction of the elements present. The first is removed by treatment with water; and the residuum serves for the manufacture of lead compounds, or may be reduced to the metallic state by fusion in the usual manner.