118 YEAST 



IV 



hydrogen and carbon, brought to the state of an oxyd by means 

 of a certain proportion of oxygen ; and these three elements are 

 combined in such a way that a very slight force is sufficient to 

 destroy the equilibrium of their connection." 



After giving the details of his analysis of sugar 

 and of the products of fermentation, Lavoisier 

 continues : 



' ' The effect of the vinous fermentation upon sugar is thus 

 reduced to the mere separation of its elements into two portions ; 

 one part is oxygenated at the expense of the other, so as to form 

 carbonic acid ; while the other part, being disoxygenated in 

 favour of the latter, is converted into the combustible substance 

 called alkohol ; therefore, if it were possible to re-unite alkohol 

 and carbonic acid together, we ought to form sugar." * 



Thus Lavoisier thought he had demonstrated 

 that the carbonic acid and the alcohol which are 

 produced by the process of fermentation, are 

 equal in weight to the sugar which disappears; 

 but the application of the more refined methods 

 of modern chemistry to the investigation of the 

 products of fermentation by Pasteur, in I860, 

 proved that this is not exactly true, and that 

 there is a deficit of from 5 to 7 per cent, of the 

 sugar which is not covered by the alcohol and 

 carbonic acid evolved. The greater part of this 

 deficit is accounted for by the discovery of two 

 substances, glycerine and succinic acid, of the 

 existence of which Lavoisier was unaware, in the 



1 Elements of Chemistry. By M. Lavoisier. Translated ly 

 Robert Kerr. Second Edition. 1793 (pp. 186196). 



