( 716 ) 



The three aliphatic terpenes investigated by nie (the isomer of 

 ocimene proved later on to be also an aliphatic terpene) form together 

 a closely related, natural group which, according to my struc- 

 tural formulae, embraces the dehydratation products of the terpene 

 alcohol, linaloöl, which occurs so widely in the vegetable kingdom. 

 The ocimene obtained by distillation in vacuo over metallic sodium 

 is an optically inactive liquid of an agreeable ester-like odour, which 

 possesses the following constants : 



sp- gi'-is "d.jg b.p. at 30 mM. b.p. at ordinary pressure. 



0,8031 1,4857 81° 172°,5. 



Whilst it boils constantly at diminished pressure, the boiling point 

 at the ordinary pressure does not remain constant for a minute, and 

 after 25 minutes the original product is found to be nearly wholly 

 converted into an isomer, which boils 17° higher than ocimene. By 

 fractionation in vacuo it may be obtained pure, and it then possesses 

 the following constants ') : 



sp. gr.,s nd. b.p. at 12 niM. b.p. at 750 mM. 

 0,8182 1,5296 81° 188^ 



The myrcene was partly prepared by myself from the oil of Bay, 

 for another part I used a myrcene, most willingly held at my 

 disposal by the firm of Schimmel and Co. In accordance with others, 

 I found for the myrcene the following constants : 



sp. gr.i5 nd.ij b.p. at 760 mM. 

 0,8013 1,4700 166° 



At the ordinary temperatui-e these terpenes are stable, except 

 myrcene, which then undergoes a slow polymerisation; the isomer 

 of ocimene is pretty soon altered in strong daylight. The chemical 

 i-eagents which can be absorbed by unsaturated compounds are 

 readily taken up by these terpenes. Up to the present, however it 

 has not been possible to isolate Avell-defmed additive products, with 

 the exception of the compound formed from myrcene and hydrogen. 

 Crystallised derivatives of these terpenes are as j^et quite unknown, 

 which very much impedes their detection in ethereal oils and their 

 investigation. If the chemistry of the aliphatic terpenes is not to 

 experience the same fate as that of the cyclic terpenes before Wallace's 

 researches, it now becomes all important, to devise a further charac- 

 teristic, based, if possible, on crystallised derivatives. The following 



1) This change of ocimene into an isomer has been noticed and already communi- 

 cated by VAN RoMBURGH (l.c). The constants I found agree with those previonsyl 

 observed by im. I followed his directions for the preparation of ocimene from 

 the ethereal oil. 



