515 



applied to the series of bodies homologous to marsh-gas. In fact, 

 we have learnt by the beautiful researches of M. Berthelot that ole- 

 tiant gas and its homologues are capable of being transformed into 

 alcohols by the absorption of two equivalents of water ; olefiant gas 

 furnishes by this reaction ordinary alcohol, and propylene, propylic 

 alcohol ; thus 



C 4 H 4 +2HO=C 4 H 6 O 2 , 



Olefiant gas. Ethylic alcohol. 



C 6 H 6 + 2HO = C 6 H 8 2 . 



Propylene. Propylic alcohol. 



Olefiant gas, then, and all its homologues are capable of furnish- 

 ing two mono-acid alcohols, exhibiting slightly different features, but 

 presenting in all their principal characters the most obvious analogy. 

 The alcohols formed by fixation of water, such as ethylic alcohol, 

 have long been well known ; in fact, the detailed study which has 

 been made during the last quarter of a century of most of their 

 derivatives, has exercised the most beneficial influence upon the 

 development of organic chemistry. 



The same remark does not apply to the alcohols produced from 

 these same hydrocarbons by fixation of oxygen. The history of 

 allylic alcohol, which we have endeavoured to trace in the preceding 

 pages, and to which of late important contributions have been fur- 

 nished, moreover, by MM. Berthelot and De Luca and by M. Zinin, 

 begins to throw light also upon this second group of alcohols. For 

 this reason the discovery of allylic alcohol appears to claim the 

 attention of chemists, even if it had not assisted in fixing, in the 

 system of organic compounds, the exact position of several very in- 

 teresting natural products, viz. the sulphuretted oils furnished by 

 the bulbs of the garlic (Allium sativum) and the seeds of the black 

 mustard (Sinapis nigra), which it had not been possible up to the 

 present time to group around a similar centre. 



