ON VINOUS FERMENTATION. 
45 
ART. IX. — ON VINOUS FERMENTATION. 
By M. Cagniard de Latour. 
In the year 1799, the class of physical and mathematical 
science of the Institute proposed as the subject of a prize essay, 
the following question: What are the characters which distin- 
guish, in animal and vegetable substances, the matters which 
excite fermentation from those which undergo this action. 
The prize was a medal of the value of a killogramme of gold, 
or little more than three thousand francs; this prize was re- 
newed in 1800, but was withdrawn in 1802, in consequence 
of an unfortunate event which deprived the Institute of the 
funds out of which the expense of the prize was to be de* 
frayed. 
This question remained unanswered, although it may be 
considered as interesting at the present moment, as when the 
prize was proposed. Under the idea that the Institute had 
principally in view the most important fermentation, or that by 
which saccharine substances are converted into alcohol and 
carbonic acid, the vinous fermentation, I undertook a series 
of researches thereon, but by a different mode of proceeding 
than had yet been done, — that is to say, by studying the phe- 
nomena by the aid of the microscope. 
It is known to chemists that when fresh yeast is mixed with 
a solution of sugar, and the mixture put into a vessel deprived 
of the access of air, and exposed to the temperature of about 
SO F., in a short time the solution begins to ferment, and the 
process proceeds with greater or less rapidity according to 
the proportion of the yeast used; while under the same cir- 
cumstances, the vinous fermentation does not take place but 
after a long time, when the solution does not contain yeast, 
and the saccharine solution is pure. 
It is, therefore, proper to examine with the microscope, the 
matter which has the property of causing sugar to ferment; 
this examination, as will be seen by the letter which I had the 
honor to address to the Academy on the 27th of April, 1835, 
