The residues obtained on rectifying, for commercial purposes, the oil of this species by steam, were employed for the purpose of determining the aldehydes of this Eucalyptus. The procedure adopted was that described above. A small amount of cuminal containing some aromadendral was isolated. This gave the following constants: Specific gravity at 200 C. = 0.9735; rotation aD - 3.6°; refractive index at 200 = 1.5250. The hydrazone melted at 126-127° C, and the semicarbazone at 210-2110.

The cryptal, when recovered from the neutral sodium sulphite, had a less rotation than that from E. hemiphloia, and gave a semicarbazone which melted at a slightly higher temperature, otherwise the figures were in agreement. To confirm this result, a fresh quantity of cryptal was isolated. The constants for these two samples were as follow: -

The oximes and hydrazones were liquid in both cases.

Although cryptal can thus be so well isolated, yet methods have not so far been devised whereby aromadendral and cuminal may be separated from each other in a pure condition; so that the true constants for aromadendral cannot be given with certainty. In the work undertaken for the first edition, the aldehyde was extracted from the oil of E. hemiphloia, distilled in September, and the purified crystalline sulphite compound decomposed by sodium carbonate. At that time of the year phellandrene was not detected, and cuminal was almost absent.

The constants for aromadendral from E. hemiphloia at that time were: - Specific gravity = 0.9477; rotation aD - 46.6°, and refractive index at 20° = 1.5086. The oxime melted at 84-85° C, the naphthocinchoninic acid at 247° C, and the acid at no° C. In the light of the present investigation it is apparent that a little cuminal was present also, and this is indicated by the figures given above. The analysis, however, gave results closely agreeing with those required for a C10HI4O aldehyde, and the acid was also in agreement with the C10HI4O2 molecule.

As the total amount of aldehydes extracted at that time only amounted to 3.3 per cent., it is evident that cryptal was not included.

The C10H14O aldehyde occurring in Eucalyptus oils was originally named aromadendral (Proc. Roy. Soc, N.S.W., Dec. 1900), derived from the name aromadendron given to the genus by Dr. W. Anderson, the surgeon of Captain Cook's second and third expeditions.

The constants for aromadendral from the oil of E. rostrata prepared from the crystallised sulphite compound were: - Specific gravity at 20° C. = 0.9534; optical rotation aD - 70.72; refractive index at 20° = 1.5066. The oxime melted at 84-85° C. It is thus apparent that a little cuminal was present here also. When aromadendral shall have been separated in a pure condition, it seems probable that the refractive index will be about 1.5 and the specific gravity about 0.95 at 20° C.