- 46 - 



short time after it has been left standing for 24 hours. As already 

 mentioned above, the period during which the flask is heated, as well 

 as the actual temperature, are here of importance, and definite infor- 

 mation on this point is therefore required, if comparable results are 

 to be obtained. The method followed by ourselves agrees with the 

 one recommended by B. Fischer and C. Hartwich in the Commen- 

 tary to the Pharmacopoeia : About 5 gm. of a solution of 1 gm. mustard 

 oil in 49 gm. alcohol are mixed in a measuring flask of 100 cc. capa- 

 city with 50 cc. deci-normal solution of silver nitrate and 10 cc. am- 

 monia liquid (diso 0,960); the flask is then closed, and with frequent 

 agitation left standing for 24 hours with the light excluded. 



The flask is then placed for 1 / 2 hour 1 ) in water at 8o°, during 

 which time it is again repeatedly shaken, next cooled down to the 

 temperature of the room, filled up with water to the mark, shaken up, 

 and filtered. 50 cc. of the filtrate are titrated with 1 / 10 th normal solution 

 of ammonium sulphocyanide, after adding 6 cc. nitric acid (di5<> 1,153) 

 and a small quantity of solution of iron alum, until a change of colour 

 from white to red takes place. In order to ascertain the whole quant- 

 ity of silver solution which has entered into reaction, the number of 

 cc. of ammonium sulphocyanide solution used up is doubled, and the 

 product subtracted from 50. The percentage of allyl isothiocyanate 

 in the mustard oil is obtained by means of the following formula: — 



7 8 GSNC 3 H 5 Lil^5. 



a = number of cc. of deci-normal solution of silver nitrate used up. 

 b = spirit of mustard used up in grammes. 



Mustard oil determinations carried out by us in the manner described, 

 showed in the case of natural oil a content of about 94% allyl iso- 

 thiocyanate, whilst in artificial oil about 98°/ were determined. 



Myrrh Oil. As a continuation of his work on secretions, 

 A. Tschirch 2 ) gives some information on Herabol myrrh which he, 

 jointly with W. Bergmann, has submitted to a more detailed exam- 

 ination. Although the Pharmacopoeias pronounce themselves very 

 distinctly on the mother-plant of official myrrh, Tschirch considers 

 it premature to indicate any definite species; the only thing certain 

 is, that a Commiphora species of North East Africa yields the drug. 

 From the material under examination, the so-called myrrha electa of 

 commerce, the authors obtained 6 to 7°/ of an essential oil, by 



*) According to Firbas the conversion is not entirely completed within that 

 time, but we purposely do not heat for too long a period in order to avoid as 

 much as possible the co-determination of the contaminations which are more difficult 

 to decompose. 



2 ) Arch, der Pharm. 243 (1905), 641. 



