This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol2", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
This is made by simply precipitating a solution of corrosive sublimate with solution of ammonia, and washing the precipitate till the washings are tasteless. The most probable explanation of the reactions which take place is that given by Sir Robert Kane. Assuming the existence of a compound radical consisting of one equivalent of nitrogen and two of hydrogen (Nh2), which is ammonia deprived of one equivalent of hydrogen, and is denominated amidogen; it is only necessary to suppose that one of the two equivalents of chlorine, contained in the deutochloride of mercury, is replaced by one of amidogen, thus forming a chloro-amidide of mercury. To produce amidogen, one of the equivalents of hydrogen leaves a portion of the ammonia, and combines with the equivalent of chlorine lost by the corrosive sublimate, forming muriatic acid, which, combining with an equivalent of undecomposed ammonia, remains in solution as muriate of ammonia.
Ammoniated mercury is in the form of a white powder or pulverulent masses, inodorous, of a slight earthy and metallic taste, insoluble in water and alcohol, and soluble without effervescence in muriatic acid. it is decomposed and dissipated by a strong heat. it may be distinguished from calomel by undergoing no change on the addition of ammonia, and by not being blackened by trituration with lime-water. Like most of the other mercurials, it yields, according to Mialhe, corrosive sublimate to the alkaline chlorides.
Little is experimentally known of its operation upon the system; but there can be no doubt that it would produce the general effects of the mercurials. Fatal cases of poisoning by it have been reported. it is employed exclusively as a topical remedy, usually in the form of an ointment, which is officinal.
Ointment of Ammoniated Mercury, or White Precipitate Ointment (Unguentum Hydrargyri Ammoniati, US., Br.; Unguentum Hy-drargyri Ammonio-Chloridi, Lond.; Unguentum Precipitati Albi, Ed.), made by rubbing a drachm of ammoniated mercury with twelve drachms of simple ointment, is used to destroy pediculi, and as a stimulant alterative in indolent ulcers, Psorophthalmia, and various cutaneous eruptions, as scabies, chronic impetigo, and favus or scald-head.