Though not officinal, this salt has attracted considerable attention of late as a remedy in hooping cough. it is made by dissolving bromine in water of ammonia. The liquid becomes heated with the reaction which takes place, nitrogen gas escapes with effervescence, and, when the ammonia is saturated, the solution has a yellowish colour from a little of the bromine remaining in solution. By evaporation quadrilateral crystals are obtained, sometimes crossing each other at right angles. The salt has the sensible properties of bromide of potassium, but differs from it in being sublimable. Exposed to the air, it loses bromine, gradually becomes yellow, and now acquires the property of reddening litmus, owing to the formation of hydro-bromic acid. (Berzelius.)* in its effects on the system, it is asserted to be identical with bromide of potassium (Lasegue, Begbie, etc.); and there would seem, therefore, to be no occasion for its introduction into the Materia Medica; but as, in the complaint in which it is specially recommended, it and not the bromide of potassium has been the subject of experiment, it would be improper to substitute the latter salt, until it also shall have been submitted to trial, and practically found to have the identity of effect ascribed to it. Dr. Belgrave, however, while admitting the similarity of effect between these salts, considers the bromide as the less powerful of the two. {B. and F. Medico-chir. Rev., Jan. 1866, p. 231.)

* For other modes of preparing it, said to be preferable, see the U. S. Dispensatory, 12th ed., p. 1477.

Bromide of ammonium was first brought into notice as a remedy in hooping cough by Dr. G. D. Gibb, who gave it in 22 cases, most of which were cured {Lancet, Sept. 26, 1863); was afterwards employed by Dr. Geo. Harley, of London {Med. T. and Gaz., Jan. 1864, p. 82); and still later has been recommended by Dr. R. Peel Ritchie, of Edinburgh. {Ed. Med. Journ., June, 1864, p. 1095.) The general testimony, however, is, that, while it sometimes acts very advantageously in the disease, it cannot be uniformly relied on, and often fails in effecting cures. Dr. Harley states that, though it may not remove the cough, it prevents the hooping; and this opinion seems to be shared by Dr. Ritchie, who says also that he has found the remedy most successful in children over two years of age, and considers it best adapted to pure cases of the disease, uncomplicated with bronchitis or pneumonia. Dr. Harley gives a grain for every year, three times a day; doubling the dose for very stout children. Dr. Ritchie recommends from three to twelve grains daily, given in divided doses, every six hours.

Other combinations of bromine have been tried, but no one hitherto with such success as to give it a foothold in the Materia Medica. Bromide of cadmium was found by Dr. Belgrave, of the Lincolnshire Asylum, to be violently irritant to the stomach and bowels, acting energetically as an emeto-cathartic, and resembling tartar emetic, only three times as strong. {B. and F. Medico-chir. Rev., Jan. 1866, p. 231.) Tor what may be said on bromide of iron, and bromide of mercury, the reader is referred to the 12th edition of the U. S. Dispensatory, page 1477. Chloride of bromine attracted at one time some attention as a remedy for cancer, being used both internally and externally; but it failed to maintain its reputation, and is not now employed.