The specific rotations of crystallised eudesmol which we have prepared from the oils of the various Eucalyptus species enumerated below, taken in each case in about 12 per cent. chloroform solution, were not always of the same value, as seen from the following results: -

Eucalyptus hæmastoma ....

[a]D

+

38.43°

E.

Moorei...

"

35.50°

E.

Gullicki .....

"

33.65°

E.

Rossii ...

"

33.58°

E.

Macarthuri .....

"

31.75°

E.

ligustrina ......

"

30.02°

E.

phlebophylla ...

"

27.07°

After two years the comparatively unaltered sample of crystallised eudesmol from E. Macarthuri, mentioned previously, had however lowered slightly in specific rotation to [a]D + 30.46°. When distilled at 10 millimetres, the product had again risen to [a]D + 31.68°, and thus in agreement with that of the original determination. That two optical isomers are present in ordinary eudesmol is indicated from the above, and also from the results obtained with the sublimed crystals from the liquid eudesmol of E. Macarthuri, as illustrated previously. The specific rotation of the sublimed product was [a]D + 37'64°, and that of the transparent light amber coloured, brittle residue [a]D + 24.93°. The mean of these results is [a]D + 31.28°, almost identical with that for the original eudesmol.