Chemistry of Essential Oils

318 THE CHEMISTEY OF ESSENTIAL OILS

OIL OF AJOWAN SEED.

This oil is the product of distillation of the fruit of the herb

Ptychotis Ajowan (Carum Ajowan), a plant cultivated in many parts of

Egypt, Persia, Afghanistan, and Bengal. The fruit yields from 3 to 4

per cent, of oil. It has the following characters :—

Specific gravity.

Optical rotation.

Refractive index

Phenols

0-910 to 0-930

+ 1° „ + 5°

1-4980 „ 1-6005

45 to 60 per cent

The characteristic odour of the oil is due to the presence of thymol.

In addition, cymene, a-pinene, dipentene, and y-terpinene are present.

The oil itself is used to a certain extent in India for medicinal purposes,

but its principal use is for the preparation of thymol. According to

Stohmann, carvacrol is also present, but this statement requires con-

firmation.

Experimental cultivations of ajowan seed have been made in the

West Indies, but, so far, not on a commercial scale. Ajowan seeds

grown in the Seychelles yield about 9 per cent, of oil containing 38 per

cent, of thymol, and seeds grown in Montserrat yield 3 per cent, of oil

containing 54 per cent, of thymol.^1

OIL OF ANGELICA.

All parts of the herb Angelica officinalis (Angelica Archangelica)
yield essential oils, of which the best known is that distilled from the
fresh root. The plant is a native of Europe, on mountains or river
sides, especially in Lapland, Sweden, Norway, Germany, etc. It is
cultivated to a considerable extent in Saxony, but is comparatively rare
in Britain. Although the root -oil is that mostly used, and held in high
esteem, according to Schimmel & Co. the seed oil is preferable to this.
Angelica root oil is a light yellow or reddish limpid liquid of strong
aromatic odour and pungent taste. The yield from dried roots grown
in the Saxon Erzgebirge is from 0

• 5 to 1 per cent, of oil. The specific
  gravity varies from -854 to '918, that from the dried root usually having
  a higher specific gravity than that from the fresh root.
  The oil has the following characters:—
  Specific gravity 0-854 to 0-918
  Optical rotation + 16° , + 41°
  Refractive index 1-4770 , 1*4880
  Acid value 1 , 4
  Ester „ 12 , 40
  ,, ,, (after acetylation) 50 ,, 75
  On long standing crystals are deposited, which according to Gior-
  dani have the composition C 32 H 62 O 6 , and melt at 74° to 77°. Beilstein
  2

showed that the oil contains one or more terpenes. Naudin^3 confirmed
this, and Schimmel & Co. have shown that amongst the lower boiling
fractions of the oil, dextro-phellandrene exists. Ciamician and Silber 4
showed that the crystalline bodies (of which they separated two) exist-
ing in the oil were probably oxyacid anhydrides. Hydrocarbons, prob-
ably sesquiterpenes, were also found, which distilled at 240° to 270°,

(^1) Bull. Imp. Ins*., xvi. 1, 30. (^2) Berichte, 15 (1882), 1741.
»Ibid, 16 (1883), 1382. 4 Ibid., 29 (1896), 1811.