During the investigation of the constituents of Polygonum Persicaria, L. (Ger. Knoeterich), the herb of which is much used in Russia as a popular remedy, P. Horst1) obtained 0,053 p. c. of volatile oil. It consisted in large part of a mixture of volatile, fatty acids, of which acetic acid and butyric acid were isolated in the form of their silver salts. The balance of the oil contained a crystalline camphor-like substance named persicariol, and a liquid body.