372 ODOROGRAPHIA. 
oil has been found to be 0:901, of Sussex oil (1889) 0-911, ditto 
(1890) 0:924%*. It rotates polarized light to the left; several 
foreign oils of rosemary rotate it to the right. Between 16° and 
17° C, it dissolves in all proportions in 90-volume per cent. 
alcohol, forming a clear solution. The admixture of turpentine, 
which in commercial oils is often found to the extent of 50 per 
cent., may be sought for by Langbeck’s test +. He states that 
oil of rosemary should dissolve one-tenth part of salicylic acid, but 
if it contain 10 per cent. of turpentine the solubility is reduced to 
1 in 24; oil of turpentine, when freshly distilled, dissolving only 
G25 part. | 
Oil of rosemary is very frequently adulterated with petroleum 
(necessarily the heavier portions of petroleum). It may be 
detected and approximately estimated by exposing the oil to the 
heat of a water-bath in an open dish until the odour of rosemary 
is practically lost, the residue consisting of petroleum and a slight 
resinous portion which is always left by the oil. Oil so adulterated 
is of course less soluble in alcohol proportionately to the amount 
of adulteration. Pure English oil is soluble in 5 volumes of 
rectified spirit of 0°838; some adulterated samples tested in this 
way required from 20 to 30 volumes of such spirit to effect 
solution. Samples of rosemary oil adulterated with alcohol 
naturally require a less volume of the solvent than pure oil; some 
samples tested required 34 and 43 volumes, according to the amount 
of adulteration. Alcohol may also be detected by agitating the oil 
with a particle of “ magenta: if pure no colour is imparted to the 
oil, but if adulterated the dye dissolves, the colour being deeper 
the greater the quantity of alcohol present ¢. These tests may be 
apphed to other oils; but the magenta-test is not applicable to 
all—for instance, oil of cloves. 
The sp. gr. of pure Italian (Dalmatian) oil of rosemary has been 
found to be 0-901 to 0:907 at 15° C., and it requires 12 volumes 
of alcohol of 0°864 to effect solution§. The sp. gr. of Spanish oil 
has been observed as 0°892 at 15° C., and the French at various 
figures between 0°88] and 0-907, but there seems some diversity of 
opinion as to the true sp. gr. of pure French oil. Messrs. Schimmel 
* Cripps, Pharm. Journ, [3] xxi. p. 987. 
+ Year-Book of Pharmacy, 1885, p. 126. 
t Cripps, Pharm. Journ. [8] xx. p. 415. 
§ Bericht, Oct. 1888. 
