HYDROSULFHATE OF AMMONIA.

271

of the vapour of this substance in humoral asthma with temporaryadvantage.

Administration. —Tli e ointment of iodide of sulphur is composed ofiodide of sulphur and lard. The proportions vary according to circum-stances : usually from 10 to 30 grains of the iodide to an ounce of lard.Magendie ’s formula; are 1 part of iodide to 18 or 19 of lard.

Ammo'meB Hydrosul'phas.—Hydrosulphate of Ammo'nia .

History and Synonymes. —This compound is said to have been firstprepared in the seventeenth century by Boyle or Beguin: hence theterms Boyle's fuming liquor and Beguin's sulphuretted spirit, applied toone variety of it. The ordinary designation of it is hydrosulphuret ofammonia , or hepatized ammonia. Berzelius calls it sulphuret of ammo-nium.

Natural History. —It is evolved from decomposing animal matter,as in privies, with hydrosulpliuiic acid and nitrogen.

Preparation. —It is prepared, according to the Edinburgh , Dublin,and United States Pharmacopoeias , by passing hydrosulphmic acid gas(sulphuretted hydrogen) into water of ammonia to perfect saturation.

Properties. —-As thus prepared the solution of hydrosulphuret ofammonia is a liquid, having a greenish yellow colour, a very foetid odour,and an acrid disagreeable taste. The mineral acids decompose it, evolvehydrosulphuric acid, and precipitate sulphur. A considerable number ofmetallic solutions have precipitates produced in them by the addition ofliydrosulphate of ammonia. Thus with the salts of lead, bismuth,silver, and copper, the precipitates are blackish ; with those of antimony,red; with those of cadmium and tin (pcrsalts), and with the arsenites(on the addition of an acid), yellow; lastly, with the salts of zinc,white. In all these cases the precipitates are sulpliurets of the respectivemetals.

By exposure to the air it attracts oxygen and deposits sulphur: itsaction on metallic solutions is then considerably modified. For example,if two or three fluidrachms be exposed to the air, in a wine-glass, for aday or two, the solution will then be found to have the property ofcausing a red precipitate with the salts of lead, yellow with tartaremetic, and white with arsenious acid.

Characteristics. —Its odour will readily distinguish it. As a sul-phuret or hydrosulphuret it is known by its action on the metallic solu-tions already noticed. Caustic potash causes the evolution of am-monia.

Composition. —It is composed of hydrosulphuric acid and ammonia,in the following proportions:—

Eq.

Eq.Wt.

Per Cent.

Vol.

Hydrosulphuric Acid . . .

. 1 .

. 17 . .

. 50-00

Hydrosulphuric Acid gas . .

. . . 1

Ammonia.

. 50-00

Ammoniacal gas.

. . .2

Hydrosulphate of Ammonia

. 1 .

. 34 . .

. 100-00

The fuming liquor (liquor fuinans Boyli) obtained by distilling fourparts of slacked lime, two of hydrochlorate of ammonia, and one of sul-