STUDIES ON FERMENTATION. 



239 



which was sufficient to impregnate the saccharine liquid con- 

 tained in the flask. In this manner it is possible to introduce 

 as small a quantity of yeast as we wish, a quantity the weight 

 of which, we may say, is hardly appreciable. The yeast sown 

 multiplies rapidly and produces fermentation, the carbonic acid 

 gas from which is expelled into the mercury. In less than 

 twelve days all the sugar had disappeared, and the fermentation 

 had finished. There was a sensible deposit of yeast adhering 

 to the sides of the flask ; collected and dried it weighed 2*25 

 grammes (34 grains). It is evident that in this experiment the 

 total amount of yeast formed, if it required oxygen to enable it 

 to live, could not have absorbed, at most, more than the volume 

 which was originally held in solution in the saccharine liquid, 

 when that was exposed to the air before being introduced into 

 the flask. 



Fig. 59. 



Some exact experiments conducted by M. Raulin in our 

 laboratory have established the fact that saccharine worts, like 

 water, soon become saturated when shaken briskly with an 



