=Ammonium, Benzoate of.= _Prep._ 1. Dissolve benzoic acid in ammonia solution to saturation, then further add ammonia in slight excess, and crystallise by refrigeration, or in vacuo. 2. (LIQUID; SOLU′TIO AMMONIÆ BENZOA′TIS, L.) As the last, but without evaporating the solution. _Prop., &c._ Very soluble and very difficult to crystallise. If the solution is boiled for a short time and then abandoned to spontaneous evaporation, crystals of ACID BENZOATE OF AMMONIUM are deposited. It is used chiefly as a chemical test; but has been recently recommended in chronic bronchitis, old coughs, &c.; and to check the formation of chalk-stones and urinary calculi.——_Dose_, 10 to 15 gr.; (of the solution) 15 drops to 1 fl. dr., or more. See BENZOIC ACID. =Ammonium, Bromide of.= NH_{4}Br. _Syn._ AMMO′′NII BROMI′DUM, A. BRO′MIS, L.; HYDROBROMATE D’AMMONIAQUE, BROMURE D’AMMONIUM, Fr. A salt which is obtained from hydrobromic acid, bromide of iron, &c., by similar processes to those adopted for the iodide. The following process for the preparation of bromide of ammonium is from the formula for the new medicaments adopted by the Paris Pharmaceutical Society: “Add bromine very slowly to a solution of ammonia, with continual stirring, until the liquid remains faintly and persistently coloured by a slight excess of bromine.” It forms white prismatic crystals; and, in its general properties, resembles bromide of potassium. It is volatile, and easily decomposed. Used as a nervine in hysterics; especially useful for sleeplessness where there is no organic disease; given in epilepsy when bromide of potassium fails.——_Dose_, 2 to 20 grains. =Ammonium, Carbonates of=[47]—— [Footnote 47: For complete information respecting the various carbonates of ammonia consult Dr Divers’ papers in the ‘Journal of the Chemical Society.’] =Ammonium, Carbonate of.= _Syn._ NEUTRAL CARBONATE OF AMMONIUM. Equal parts of dry sal ammoniac and sodium carbonate are heated to form the neutral ammonium carbonate of commerce, which sublimes. Solid crystalline substance, with a strong ammoniacal odour, volatile and soluble. _Uses, &c._ In the solid form it is not now used in medicine; but it is indirectly employed in several liquid preparations in which the sesquicarbonate is ordered. It is superior to any other preparation of ammonia for filling smelling bottles; as it is not only more pungent, but does not lose its pungency by keeping. It volatilises more quickly than the sesquicarbonate, and the residuum, unlike that of the latter salt, continues as odorous as ever. It is the basis of several of the most popular and esteemed advertised smelling salts of the shops. Spirit of hartshorn is an impure solution of this salt, originally obtained by distilling hartshorn or bones.