336 odoeogeaphia. 



Volumetric, 

 salicylic methyl 



SPECIMEX. ^^jj^_ SALICYLATE. 



l.—Genuine oil of Gaultheria 90-15% = 99-30% 



2.— Genuine oil of Sweet Birch 90*20 „ = 99-40 „ 



3. — Commercial oil of Wintergreen 90-15 „ = 99*30 „ 



Gravimetric 



SALICYLIC methyl 

 SPECIMEN. ^^jp^ SALICYLATE. 



1.— Genuine oil of Gaultheria 89-56% = 98-65% 



2._Genuine oil of Sweet Birch 90-54 „ = 99-72 „ 



3. — Commercial oil of Wintergreen 90-65 „ = 99-85 „ 



" Three more specimens of the commercial oil obtained from 

 different manufacturers of natural salicylic acid, were estimated, 

 by the volumetric method, one of which proved to be absolute 

 methyl salicylate, the other two 99-10 per cent, and 99-50 

 per cent, respectively. The method has since proved effective 

 in one instance in detecting an oil offered for sale by a 

 travelling broker, which contained only 68 per cent, of methyl 

 salicylate."* 



The assay of essential oils by saponification formed the subject 

 of an interesting communication read before the Pharmacy 

 Section of the Xaturforscher Society at Cologne by Kremel, 

 in which it was proposed to utilise the differences in the 

 behaviour of essential oils towards alcoholic potash solution 

 as a means of determining their identity and purity.f The 

 author stated that he had applied this test to a large number of 

 essential oils, with the following general results : — Genuine rose 

 oil contains scarcely any saponifiable constituent, but eight 

 or ten samples of geranium oil, from diff'erent countries, each 

 gave tolerably high saponification numbers. Lavender oil gave 

 very high saponification numbers ; lemon oil, on the contrary, 

 did not. Artificial bitter almond oil gave higher saponification 

 numbers than the natural oil, and upon decomposing the saponified 

 mass from the latter with acids, a crystalline precipitate was 

 formed, amounting to 40 or 50 per cent, of the oil used. A 



* Pharmaceutical Eecord. 



t Pharm. Centralh., 4th October, 1888, p. 482. 



