Chemistry of Essential Oils

494 THE CHBMISTEY OF ESSENTIAL OILS

TROP^EOLACE^E.

OIL OF TBOP^OLUM.

The Nasturtium (Tropaolum majus) yields about

• 04 per cent, of a
  strongly smelling essential oil, when the green plant is distilled with
  steam. The vessel should be well tinned inside, on account of the sul-
  phur contained in the oil. Hofmann investigated this oil in 1874, prob-
  ably distilling it without previous crushing. In the oil he found benzyl
  cyanide. Gadamer l distilled the plant, first; well minced, with steam,
  and extracted the small quantity of oil from the distillate with ether.
  He found that it contained 86 per cent, of benzyl-thiocarbimide. He
  considers this is due to the fact that there is in the plant an enzyme
  which decomposes the glucoside present, with the formation of this body.
  He suggests that by not crushing the plant the enzyme is destroyed before
  it can decompose the glucoside which is distributed all through the cells,
  and that the benzyl cyanide obtained by Hofmann was a product of
  decomposition of the glucoside through the distillation.

MELIACE/E.

CEDRELA WOOD OILS.
One of the most useful woods in Jamaica is that obtained from
Cedrela odorata, an immense forest tree. It is a native of the Caribbee
Islands and the Barbadoes. Its timber has a pleasant odour of cedar,
hence it is frequently spoken of as Jamaica or Honduras cedar, and from
the wood most of the ordinary cigar boxes are made. The wood yields
from '5 to 1 per cent, of oil of a light blue colour, and having the follow-
ing characters :—

Specific gravity

Optical rotation

Refractive index

Acid value

Ester „.

0-923 to 0-950

very variable

1-5040

2 to 4

40 ,, 45

The cedar-wood oils from La Plata and Punta Arenas (Costa Eica),

which have been referred to under true cedar-wood oil, are probably

obtained from closely related trees of this order. The oil from La Plata

is of a light blue colour, has a specific gravity -928, and is optically in-

active. That from Punta Arenas is yellow, of specific gravity -915 and

optical rotation - 6°. It consists chiefly of cadinene.

Corinto cedrela wood yields an oil of specific gravity 0*906 and optical

activity - 17. A Cuban wood gave an oil of specific gravity 0*923 and

optical activity + 18°, consisting largely of cadinene.

An oil has also been distilled from the Brazilian cedrela wood (Cedrela

brasiliensis), which yields about 0*5 per cent, of oil of a pale bluish colour,

of specific gravity 0

*

9348 and optical rotation - 0° 22'. There is also a

cedrela tree in Brazil, Cedrela Velloziana, which yields a small amount

of essential oil having an odour recalling that of asafcetida, but whose

characters have not been investigated.

(^1) Arch. Pharm. (1899), 237.