Chemistry of Essential Oils

376 THE CHBMISTKY OF ESSENTIAL OILS

OILS OF THE ANGOPHORAS.

So far only six species of the genus Angophora have been described.

They are all Australian plants, and are closely allied to the Eucalypts,

and believed by Baker and Smith to be the prototypes of the latter;

these scientists have investigated the plants, and Smith

l

has examined

the essential oils.

The following table gives the yields of oil distilled from material

cut as would be done for commercial oil distillation:—

0-31

0-19

0-13

0-013

0-005

traces

Angophora Bakeri per cent.

melanoxylon

sp. undescribedbed.

lanceolata (S>ydney)

^Varialda)

inter media.

subvelutina.

cordifolia ,

The oil from Angophora Bakeri has the following characters:—

Specific gravity ........ 0*8719

Optical rotation + 35-6°

Refractive index 1-4660 at 22°

The crude oil was light lemon-coloured, had an indistinct odour at

first, but distinctly a secondary aromatic one. The chief constituents

were dextro-rotatory pinene, geraniol, geranyl-acetate, geranyl-valerian-

ate, a small amount of a sesquiterpene, together with a little volatile

aldehyde, and most probably a minute quantity of amyl-acetate. No

other terpene than pinene was detected and cineol was quite absent.

' The oil from Angophora melanoxylon has the following characters :—

Specific gravity

Optical rotation

Refractive index

0-8809

+ 24-9°

1-4678 at 21-5°
The constituents of this oil are identical with those of Angophora
Bakeri, the geranyl valerianate, and the sesquiterpene being present in
rather larger amount.
Angophora lanceolata yields an oil having, the following characters :—
Specific gravity ......
Refractive index ......
Saponification value
The constituents are similar to those of
described.
The approximate composition of the oils
and Angophora melanoxylon are as follows :—

Dextro-rotatory pinene .....

Free geraniol

Geranyl acetate

Geranyl valerianate .....

Water, volatile aldehydes, and low-boiling esters

Sesquiterpene and undetermined.

0-927

. 1-4946 at 20°

the otherspeci

24-2

• species just

from Angophora Bakeri

Angophora

Bakeri.

Per Cent.

. 78-0
4-5
6-7
6-1
1-0
3-7
100-0

Angophora

Melanoxylon.

Per Cent.

72-0

5-1

6-9

9-6

1-0

5-4

100-0

1

Jour, and Proc. Roy. Soc., N.S.W., xlvii. (1913), 106.