Semmler and Tobias (loc. cit.) give the following constants which they had determined for eudesmol:- melting point 780 C.; boiling point 1560, at 10 millimetres pressure; specific gravity at 200 = 0.9884; specific rotation in a 12 per cent. solution of chloroform [a]D + 31.21°; refractive index at 20° = 1.516, molecular refraction calculated for CI5H26O with one double bond = 68.07; found 67.85.

They point out that from the molecular refraction eudesmol evidently contains two rings and one double bond.

When eudesmol was acetylated it yielded an acetate boiling at 165 to 170° at 11 millimetres pressure. Reduction with hydrogen and platinum black gave dihydro-eudesmol, an alcohol melting at 82° and boiling at 155-160° at 12.5 millimetres, and the acetate from this boiled at 158-164° at 10 millimetres.

When boiled with absolute formic acid dihydro-eudesmol gave dihydro eudesmene, a body boiling at 126-130° at 10 millimetres.

When boiled with go per cent. formic acid eudesmol was converted into eudesmene, which substance boiled at 129-132° at 10 millimetres; had specific gravity at 20° = 0.9204; specific rotation at 20° [a]D + 49°; and refractive index at 20° = 1.50738. The molecular refraction from this shows clearly that the sesquiterpene contains two rings and two double bonds, and belongs to that group of sesquiterpenes which is derived from hydrogenated naphthalene. When eudesmol was shaken with hydrogen chloride glacial acetic acid, eudesmene dihydrochloride was formed; this substance melted at 79-80° and was identical with the hydrochloride which was formed by the addition of hydrogen chloride to eudesmene.

Later, Semmler and F. Risse (loc. cit.) undertook further investigations with eudesmene, which they had prepared by saturating a solution of eudesmol in glacial acetic acid with hydrochloric acid. On evaporating this solution in vacuo at 50-60°, eudesmene dihydrochloride was obtained, and this when purified from alcohol melted at 70°. It was then boiled with alcoholic potash under a reflex, the resulting product being eudesmene, possessing the following properties: - Boiling point 122-124° at 7 millimetres pressure; specific gravity at 20° = 0.9196; specific rotation [a]D + 54.6°; refractive index at 20° = 1.50874. When the acetic acid solution was reduced with hydrogen in the presence of platinum, tetrahydroeudesmene was formed. This had boiling point 122.122.5° at 7.5 millimetres; specific gravity at 20° = 0.8893; specific rotation [a]D + 10.12°, and refractive index at 20° = 1.48278.

It was also shown that the reduction of eudesmol by hydrogen in the presence of platinum proceeded differently in an ethereal solution to what it did in the presence of glacial acetic acid; in the former case the hydrogenation only led to dihydroeudesmol, while in the latter case both the double bond and the hydroxyl group were replaced by hydrogen.

We have found the hydroxyl group in eudesmol to be very unreactive, except in the case of acetic anhydride, and have failed to combine it with phthalic anhydride, benzoic acid anhydride, benzoyl.chloride, or phenyl. isocyanate.