( 701 ) 



oxidation had set in, the absorption proceeded more rapidly so that 

 on the secoiid day, for instance, oxygen was being absorbed at the 

 rate of 2 cc. per hour. 



Still, I should not feel justified in saying that hops-terpene and 

 myrcene are not identical, merely on account of the difference in 

 oxygen absorption, because further experiments have taught me that 

 under certain undefined conditions even this hydrocarbon may some- 

 times be left in contact with oxygen for a day without absorbing a 

 notable quantity '). But as soon as the absorption has commenced 

 it proceeds at a fairly rapid i-ate. 



By the action of oxygen a colorless viscous substance is obtained. 



I hope to refer to these experiments more fully later on. 



In the same paper Chapman expresses some doubts as to the 

 "chemical individuality" of ocimene. Although I have already pointed 

 out in my previous communication that the boiling point at 20 mm., 

 the behaviour on distilling at the ordinary atmospheric pressure and 

 the index of refraction of ocimene and myrcene differ considerably, 

 I will now adduce additional facts which undoubtedly prove that 

 ocimene and myrcene are different compounds. 



Mr. C. J. Enklaar, who has taken up the study of ocimene in the 

 Utrecht laboratory, repeated in the first place the determination of 

 the index of refraction of this hydrocarbon and for a product care- 

 fully fractioned over metallic sodium he found y^,j9 = 1.4872 and 

 ??,^^ 1.4867, which values satisfactorily agree with 1.4861 previously 

 found by myself by means of another apparatus. For myrcene, Power 

 and Kleber have found 7^/^ = 1.4674 whilst I had, previously, found 

 1.4685. 



Semmi.er (loc. cit.) has shown that myrcene is reduced by sodium 

 and alcohol to dihydro-myrcene. On applying this reaction to ocimene, 

 Mr. Enklaar obtained a dihydro-ocimene, which not only differs 

 from dihydro-myrcene ^) as regards boiling point, specific gravity 

 and index of refraction, but also by the fact that it yields with 

 bromine a crystaUised additive compound. These investigations are 

 being continued. 



1) Nol improbably, traces of moisture or of products of oxidation exercise a 

 catalytic influence. A retardation was noticed when ocimene freshly distilled over 

 metallic sodium was placed in dry oxygen. 



2) Dihydro-ocw2e;?e boils at 1G8^ at 7G3 mm. At 21 mm. the boiling point is 

 65°. Sp. gr. at 15° 0.775. The boiling point of diliydrü-Wi//m'«(^ is 17r.5— 173°.5 

 at the ordinary pressure and its sp. gr. 0.7802. 



