Chemistry of Essential Oils

252 THE CHEMISTEY OF ESSENTIAL OILS

Gibbs,^1 and the genuine patchouli, as its var. suavis, and it was not until 1896 2 that it was shown that the true patchouli (Pogostemon patchouli Pellet.) was a distinct species and a native of the Philippine Islands. The native Indian patchouli was then referred back again to Pogostemon Heyneanus Wall. It is practically certain that some other leaves from closely allied species are from time to time to be found in " Java patchouli leaves''. Distillation of the leaves in the Straits Settlements is carried out in stills with false-bottom cylinders, usually with steam at a pressure of about 1*3 atmospheres, when a yield of about 1*5 per cent, is obtained. By using higher pressure a larger yield of oil results, but the quality is inferior. By very prolonged distillation up to 2 * 6 per cent, has been obtained in the native distilleries, but in Europe, where most of the leaves are distilled for perfumery purposes, a yield of 4 per cent, is obtained from the true patchouli leaves, and of about 1 to 1*5 per cent, from the Java leaves. There appears to be no doubt that the question of fermentation of the leaves has an important bearing on the yield of oil. A. W. K. de Jong^3 has carried out an investigation in regard to the oil obtained from plants during various stages of their development. As

No.

1 2 3 4 5 6 7 8

>tate of the Leaves.

Fresh

Dried Fermented

Fresh

Dried Slightly fermented Strongly fermented

Colour.

bright yellow

Odour.

faint faint patchouli odour

terpene- like

faint patchouli odour calamus- like calamus- like faint patchouli odour

dlf.0. ax>.

I. Singapore Oils. 0-9655

0-9587

0-9628

II.

0-9344

0-9450

0-9168

0-9229

0-9210

- 51° 18'

-50° 58'

-52° 33'

Java Oils. -15° 20'

-15° 20'

+ 3° 15'

+ 2° 32'

- 0°26'

1-50820

1-50766

1-50784

1-50050

1-50483

1-50030

1-50058

1-50207

Acid No.

1-5

.—

0-9

0-8

—

Ester No

2-0

1-1

1-5

9*9

5-8

6-1

4-9

5-0

Solubility in 90 per Cent. AlcohoL

Soluble in 0'8 vol. if 1-5 to 5 vols. are added, the solution becomes cloudy and afterwards again clear. Soluble in 6 to 7 and more vols. Soluble in 7 and more vols.

Soluble in 0'3 and more vols. (soluble in about 10 and more vcls. 85 per cent, alcohol). Soluble in 0*6 and more vols. (insolu- ble in 10 vols. 85 per cent, alcohol). Soluble in about 10 and more vols. Soluble in about 10 vols. with separa- tion of paraffin. Soluble in 8 and more vols.

(^1) Pharm. Jour. (4), xxvi. 349. (^2) Ibid. (4), ii. 223. 3 Teysmannia (1906), No. 6.