- 132 - f 



quantity of thymol employed. 1 cc. decinormal thiosulphate solution 

 = 0,007506 grams thymol. 



On the estimation of cinnamic acid in storax balsam see p. 126. 



Physical Notes. 



As stated on p. 160 of our Report of April 1912, Hantzsch regards 

 the absorption-method as much more sensitive than the refraction method 

 which is employed by Auwers for constitutional determinations. Auwers 1 ) 

 disputes this and many other assertions of Hantzsch. Auwers holds that 

 it is unnecessary first to fractionate in vacuo the terpene hydrocarbons of 

 which the spectrochemical properties are to be examined, as is done by 

 Hantzsch, and he believes that distillation at ordinary pressure is sufficient. 

 While not at all doubting the great sensitiveness of the absorption-method, 

 Auwers believes that it is still very questionable whether by that method 

 it is possible to obtain the same definite information concerning questions 

 of chemical constitution as by the refraction-method. It is not yet possible 

 to say whether there is any prospect of such definite information being 

 afforded by the absorption -method, inasmuch as extensive systematic 

 investigation is needed to answer the question. 



Soon afterwards a reply by Hantzsch 2 ) made its appearance, from which 

 we will only abstract the points which apply to our particular industry. In 

 reply to a question by Hantzsch, Wallach has informed him that although he 

 regards it as desirable to state the boiling-point of the terpenes at ordinary 

 pressure, when it was a question of obtaining the body in the pure state, 

 and of determining its constants, he has always proceeded by distillation 

 in vacuo, and has laid stress upon the liability to change of, say, pinene, 

 phellandrene, terpinene, Sc, when distilled under ordinary pressure. 



In our last Report 3 ) we mentioned some papers by Golodetz 4 ) on 

 "New methods for the separation of mixtures with closely approximating 

 boiling-points, and of mixtures which boil without decomposition", and 

 we then stated that we intended eventually to return to the subject later 

 on. Now that Golodetz's publication is before us in its entirety, such a 

 further reference would be superfluous, seeing that those parts of the 

 work which interest us, but with which we were already familiar, have 

 already been dealt with in their essential points in another publication 

 by Golodetz 5 ) to which we referred at the time 6 ). We have nothing to add 

 to the particulars which we then gave. 



x ) Berl. Berichte 45 (1912), 963. 



2 ) Ibidem 1742. 



3 ) Report April 1912, 156. 



*) Chem. Ztg. 36 (1912), 273, 297, 302. 



5 ) Journ. Russ.phys. chem. Soc. 43 (1911), 1041. Quoted from Chem. Zentralbl. 1912, I. 68. 



e ) Report April 1912, 153. 



