The crystallizable substance, the existence of which in the bark of the horse-chestnut I noticed in a former communication to this Society, and to which I gave the name paviin, together with sesculin which it closely resembles in its properties, may be thus prepared.

A decoction of the bark having been made, and allowed to grow cold, there is added a persalt of iron, such as pernitrate, until on testing a sample by the addition of ammonia, the precipitate separates at once in distinct flocks, leaving a bright pale yellow highly fluorescent fluid, giving a mixture which filters readily. The whole is then precipitated by ammonia and filtered; about one-fourth of the ammoniacal filtrate is precipitated with acetate of lead, avoiding an excess, ammonia being added if required; the mixture is restored to solution by the addition of acetic or dilute nitric acid, added to the remainder of the first filtrate previously acidulated; the whole precipitated by ammonia and filtered; and the filtrate precipitated by ammoniacal acetate of lead and filtered. The two precipitates are collected separately, and treated with acetic acid until they are dissolved, or at least wholly broken up, filtered if need be, and set aside in a cool place. The second precipitate yields sesculin, which makes its appearance as a light precipitate, appearing under the microscope to consist wholly, of minute needles. The first precipitate yields paviin, which ordinarily crystallizes in tufts of very long slender silky crystals.