WIXTEKGREEX. 335 



but also by the odour, as the charateristic odour of the oil of winter- 

 green disappears completely during the process. 



A fictitious oil of wintergreen has been met with containing 

 large quantities of oil of sassafras and of chloroform. A mixture 

 of 4 parts of oil of sassafras and 1 part each of chloroform 

 and oil of wintergreen has a sp. gr. nearly the same as oil 

 of wintergreen. The presence of chloroform can easily be 

 detected by shaking the mixture in a moderately w^armecl 

 test-tube, when the odour of chloroform will be perceptible ; 

 by fractional distillation, between 60^ and 70° C, the chloroform 

 can be separated. The residue treated with nitric acid will 

 show the presence of oil of sassafras by turning it dark red.* 



A plan for the volumetric estimation of Methyl Salicylate 

 in oil of Wintergreen and Sweet Birch of commerce has been 

 devised by B. H. Ewing (of Ewingville, Ohio), and the results 

 communicated in a paper read before the American Pharmaceutical 

 Association. It consists in saponifying a weighed portion of 

 the oil wdth an excess of normal solution of soda and neutralisino- 



o 



the excess with normal hydrochloric acid: in detail it is as follows: — 

 Weigh 5 grams of the oil in a tared llask of 100 c. c. m. 

 capacity, and pour upon it 40 c. c. m. volumetric solution of 

 soda. Cork the flask securely and heat the contents at 60° C. 

 until the precipitate formed at first has totally disappeared. 

 Cool, remove the cork, and again apply and maintain heat at 

 the boiling point for five minutes : again cool, add enough 

 solution of phenolphthalein to impart a red colour, and then 

 enough normal hydrochloric acid to render the liquid neutral, 

 as will be sharply indicated by the disappearance of the red 

 colour. Subtract the volume of acid required from 40 and 

 multiply the remainder by 0-138 (one-thousandth of the molecular 

 weight of salicylic acid), and the resulting product by 20 to get 

 at the percentage of salicylic acid ; or multiply the remainder by 

 0*152 (one-thousandth of the molecular weight of methyl salicylate) 

 and the resulting product by 20 to get at the percentage of methyl 

 salicylate. 



This method w^as applied to three specimens of oil, the following 

 table showing the results compared with those obtained by a 

 gravimetric method : — 



* JacoLsen's Chemisch-Technisches Repertorium, p. 268. 



