Musk is not a substance of a constant chemical and physical constitution, the reason for this being found in the age and the different foods of the musk animal, the season in which it is killed, and the degree of dryness of the musk-substance. Water dissolves ¾ of good musk and 90 per cent. alcohol ½. The alcoholic solution is not precipitated by water. Musk further contains fat-like substances, wax, gall-substances (together 10 to 12 per cent.), glue-substances and albumen (6 to 9 per cent.), traces of lactic and butyric acids, phosphates, sulphates and hydrochlorates of the alkalies and alkaline earths, frequently strong traces of ammonium carbonate and a volatile oil, further moisture, humus-substance, and fibrous matter.
Musk, when dried, has a weak odor, which gradually becomes stronger on moistening. There are several substances which destroy the musk odor, especially bitter almonds, camphor, sulphur, acids and sulphates. The odor adhering to a mortar in which musk has been rubbed can best be removed by pounding bitter almonds in it.
Since, on account of the high price of musk, the musk animal is much hunted, there is a possibility of it becoming in time extinct. For this reason a substitute has been long searched for, and is believed to have been found, especially, in the American musk-rat (_Fiber zibethicus_), which is chiefly hunted for its skin. In this animal the musk is found in two small sacs located between the anus and generative organs, and is emitted when the animal becomes excited. According to R. S. Cristiani, this musk is invaluable for the toilet soap industry of America, it being nearly as good and strong as genuine musk. Cristiani has formerly used much of it for scenting soaps, powders, etc., but does not recommend it for essences. When used for soaps, some time is required for the odor to become refined, and if a piece of soap scented with it is stored for a few months, it would, according to Cristiani's assertion, be difficult even for an expert perfumer to distinguish the odor from that of genuine Tonkin musk.
As possible substitutes for the musk deer may further be mentioned a species of rat indigenous to the West Indies, and an antelope of North Africa. It is also said that musk derived from the Mississippi alligator has been brought into commerce. The sacs are said to be small, the odor somewhat different from that of genuine musk, resembling that of civet, but suitable for perfuming purposes.