"Take of water of ammonia, sulphuret of iron, of each four ounces; muriatic acid, eight ounces; water, two pounds and a half. Pour the acid, previously mixed with the water, on the sulphuret, and transmit the gas evolved through the water of ammonia. Preserve the solution in well-stopped phials.

Ammoniae Hydrosulphuretum, Dub. Hydrosulphuret of Ammonia.

"Take of sulphuret of iron, in coarse powder, five parts; sulphuric acid, seven parts; water, thirty parts; water of caustic ammonia, four parts. Put the sulphuret into a retort, and gradually pour over it the acid, diluted with water; and in a proper apparatus transmit the gas evolved from it through water of ammonia. Towards the conclusion of the operation apply a moderate heat to the matrass."

The addition of the diluted hydrochloric acid, ordered in the Edinburgh process by oxidising the iron, enables it to decompose the water, the hydrogen of which, dissolving a part of the sulphur, escapes in the form of sulphureted hydrogen gas, which combines, at a low temperature, with the ammonia of the solution through which it is made to pass. Mr. Cruikshank1 advises the sulphuret of iron to be prepared "by raising a piece of iron in a smith's forge to a white heat, and then rubbing it against the end of a roll of sulphur; the iron at this temperature immediately combines with the sulphur, and forms globules of pyrites (sulphuret), which should be received into a vessel filled with water: these globules are to be reduced to powder, and introduced into the proof, to which a sufficient quantity of the muriatic acid is to be added."

Qualities. - Hydrosulphuret of ammonia is of a green colour; has a very fetid odour, and an acrid, disagreeable taste. It is decomposed by the acids.

Medical properties and uses. - This preparation is a powerful sedative, lessening the action of the stomach and of the arterial system in a remarkable degree; and even in moderate doses producing sickness, vomiting, and vertigo. It was first proposed as a remedy by Mr. Cruikshank, with the view of diminishing the morbid appetite and powerful action of the digestive organs, which attend those labouring under diabetes mellitus; and its subsequent use has been confined to the treatment of that disease. The dose, to an adult, should not at first exceed v. or vj., given in a large tumbler of water, three or four times a day; and the number of drops should be gradually increased, until a slight degree of giddiness take place, when any further increase must be stopped.