— 152 — 



In our last Report (p. 121) we mentioned a paper by Fuller 1 ), in which 

 he recommended Walther's hydroxylamine method (Report April 1900, 22) 

 for estimating the camphor-content of spirits of camphor. E. K. Nelson 2 ) 

 has now investigated the general applicability of this method to ketones, 

 and has found it to give tolerably satisfactory results with carvone, pulegone, 

 camphor, thujone, and menthone. He therefore regards it as suitable for 

 the quantitative estimation of the ketones in question, especially in cases 

 where these ketones constitute the principal portion of an oil. But in the 

 case of oils in which the ketones occur only as constituents of secondary 

 importance it is necessary to make further special investigations to de- 

 termine how the other constituents behave when attacked by the reagent. 



Several determinations made by Nelson with various oils have given 

 the following results: — 



Spearmint oil 58,4 or 53,1 °/o carvone 



» 65,5 „ 66,4% „ 



n 61,4 „ 60,7°/o 



Tansy oil. . . 68,6 „ 65,4% thujone 



Wormwood oil ..... 33,2 „ 31,2% 



Pennyroyal oil 81,9 „ — °/o pulegone 



Rosemary oil 30,3 „ 30,2% camphor 



Experiments made by Nelson with fenchone showed the quantitative 

 estimation of that body to be impossible by Walther's method. 



Judging from our own present experience with this method our attitude 

 towards Nelsons's optimistic views is somewhat sceptical, but we are not 

 prepared to express a definite view on the matter. In commenting upon 

 Fuller's article at the time (Report October 1911, 121) we stated that a 

 control-test made by us for determining the camphor-content of spirits of 

 camphor had failed to give satisfactory results. 



In our October Report of 1910, p. 139, we mentioned the method for 

 testing turpentine oil which has been worked out by Louise, and which 

 is based upon the miscibility of this oil with aniline, and the determination 

 of the so-called curve of miscibility. The same author 3 ) has recently 

 applied the same principle to the examination of lavender oil, neroli oil, 

 lemon oil, peppermint oil, sandalwood oil and copaiba balsam oil. It would 

 appear that by plotting a miscibility-curve it is possible to discover adultf f 

 ration in oils of lavender and neroli and to differentiate between French, 

 Japanese and American peppermint oils. 



*) Published also as Circular No. 77 of the Bureau of Chemistry, U. S. Dept. of Agriculture. 



2 ) U. S. Dep. of Agriculture, Bureau of Chemistry. Bulletin No. 137 (20. VII. 1911), p. 186. 



3 ) Journ. de Pharm. et Chim. VII. 4 (1911), 194. 



