This was adopted at the late revision of the XL S. Pharmacopoeia. it is an excellent vesicating preparation, and now much employed as a substitute for the cerate. it consists essentially of mixed ethereal and alcoholic extract of cantharides, dissolved in collodion, which is a solution of gun cotton in ether. For an account of the mode of preparing it, the reader is referred to the U. S. Dispensatory. It should be kept in glass-stoppered bottles accurately closed, so as to prevent the escape of ether. When it is applied to the surface, the ether rapidly evaporates, leaving a coating with powerful vesicating properties, closely attached to the skin. The application may be made by means of a camel's-hair pencil; and, as the ether evaporates in less than a minute, may be repeated once or oftener, without inconvenience, if the part has not received a sufficient coating. It produces a blister in about the same time as the cerate, over which it has the advantages, that it may be more easily applied, retains its place better, and may be made to fit unequal surfaces more accurately. If the ether be prevented from evaporating by means of oiled silk, its own stimulating property aids that of the flies, and vesication takes place more speedily.