796 Transactions of the American Institute. 



the operations of art and nature, nothing is created ; an equal quantity 

 of matter exists both before and after the experiment. The quality and 

 quantity of the elements remain precisely the same, and nothing takes 

 place beyond changes and modifications in the combinations of these 

 elements. Upon this principle, the whole art of performing chemical 

 experiments depends ; we must always suppose an exact equality 

 between the elements of the body examined and those of the product 

 of its analysis. Hence, since from must of grapes we procure alcohol 

 and carbonic acid, I have an undoubted right to suppose that must con- 

 sists of carbonic acid and alcohol. From these premises we have two 

 modes of ascertaining what passes during vinous fermentation : either 

 by determining the nature of, and the elements which compose, the 

 fermentable substances ; or by accurately examining the products 

 resulting from fermentation ; and it is evident that the knowledge of 

 either of these must lead to accurate conclusions concerning the nature 

 and composition of the other. From these considerations, it became 

 necessary accurately to determine the constituent elements of the fer- 

 mentable substances ; and, for this purpose, I did not make use of the 

 compound juices of fruits, the rigorous analysis of which is perhaps 

 impossible, but made choice of sugar, which is easily analyzed, 

 and the nature of which I have already explained. This substance 

 is a true vegetable oxide, with two bases, composed of hydrogen and 

 carbon, brought to the state of an oxide by means of a certain pro- 

 portion 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 pro- 

 ducts 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 favor of the latter, is 

 converted into the combustible substance called alcohol ; therefore, if 

 it were possible to re-unite alcohol 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 



* Elements of Chemistry. By M. Lavoisier. Translated by Robert Kerr. Second edition ; 

 1793 (pp. 186-196). 



