THE ODOUR OF ROSE. 47 
some years past an “ essence of geranium” has been received from 
Java, possessing all the characters of Palma Rosa, but its exact 
botanical origin and method of production are unknown. Some 
samples of Palma Rosa have a decided odour of Lily of the Valley. 
An oil termed “ Huille essentielle de Pataque Malgache ”’ has been 
introduced from the Island of Réunion, described as distilled from 
** Andropogon fragrans”’ (evidently a fancy name), with an odour 
identical with Indian ginger-grass oil. 
The sp. gr. of “ Indian geranium oil,” according to Semmler*, 
is 0°8868 to 0°8871 at 16° C. (two specimens being examined), and 
the optical rotation 20’ to the left, in a column of 100mm. (Dr. 
Dymock found the oil to be dextrogyre, deviating the ray 39° to 
the right in a 100 mm. tube, and 78° in a 200 mm. tube ; he appends 
the remark that some samples of ‘‘ commercial” oil rotate the ray 
about 13° to the right, and some have little or no effect upon it. 
As he further remarks that all ‘‘ commercial” oil is more or less 
adulterated, it is inferred that the optical rotation is more or less 
active proportionately.) 
This oil, when pure, forms a clear solution in dilute alcohol in 
very nearly the same proportions as does oil of pelargonium, so 
that when fixed oils are present they can be easily detected. A 
process for the quantitative estimation of fixed oil by saponification 
with caustic potash has been recommended +. 
Geraniol, C,)H,,0.—This alcohol constitutes 92 per cent. of 
pure oil of “Indian geranium.” It is a colourless, strongly re- 
fractive liquid boiling at 120°5 to 122°5 C., under a pressure of 
17 mm.; by oxidation with potassium permanganate it yields 
valerianic acid, and by oxidation with chromic acid mixture it is 
converted into geranium aldehyde, C,,H,,O, which is identical 
with citral. By further oxidation with argentic oxide, Semmler 
prepared geranic acid, C,)H;,O,, a limpid oil, and by treating citral 
with acid sulphate of potassium Cymol was formed, a molecule of 
water being abstracted {. Geraniol is nearly related to, and iso- - 
meric with rhodinol, C,)H,,O, the aleohol which forms the prin- 
cipal constituent of otto of rose, and which, by oxidation, yields 
the aldehyde rhodinal, closely resembling citral as above observed. 
Geranyl chloride, C,)H,;Cl, is obtained by the action of hydro- 
chloric acid on geraniol. It is an oily liquid having an odour 
* Ber. Deutsch. chem. Ges. xxiii. p. 1098. +t Chem. News, xxx. p. 293. 
{ Ber. Deutsch. chem. Ges. xxiii, (1890) p. 3556, and xxiv. (1891) p. 203. 
