FERMENTS AND ARTIFICIAL FERMENTATIONS. 67 
properly so called, either by means of a nitrogenous 
substance of animal origin (Berthelot), or by other 
chemical and physical processes which we shall 
presently mention. But it may be questioned whether 
the nitrogenous substance of animal origin, which 
Berthelot considers to be dead, does not contain a 
living ferment. This is not admitted to be the case 
by Béchamp, whose theory will be given further on. 
Whenever fermentation is produced solely by the 
influence of physical and chemical agents, the action 
is very slow. But it is, on the other land, very rapid 
when effected by living ferments or yeast, and it is 
also much less costly, so that the latter mode of 
fermentation is preferred by manufacturers. Yeast is, 
therefore, the true agent in artificial fermentations. 
All the saccharine liquids which contain glucose or 
grape sugar, or a sugar which can be transformed into 
glucose, and also all nitrogenous substances, phos- 
phates, and ammoniacal salts, produce alcohol at a 
temperature varying between 25° and 100°, and the 
yeast of beer (of which the spores are carried through 
the air) appears and is developed at the same time; 
this occurs in the juice of grapes, beetroot, sugar- 
cane, etc. The alcoholic liquids thus produced are 
then subjected to distillation in order to extract the 
alcohol. The transformation of alcohol into vinegar 
is produced by another ferment. 
Fermentations are very common in nature. The 
transformation of sugar into lactic, butyric, and 
