IV 



YEAST 119 



fermented liquid. But about H per cent, still 

 remains to be made good. According to Pasteur, 

 it has been appropriated by the yeast, but the 

 fact that- such appropriation takes place cannot 

 be said to be actually proved. 



However this may be, there can be no doubt 

 that the constituent elements of fully 98 per 

 cent, of the sugar which has vanished during 

 fermentation have simply undergone rearrange- 

 ment ; like the soldiers of a brigade, who at the 

 word of command divide themselves into the 

 independent regiments to which they belong. 

 The brigade is sugar, the regiments are carbonic 

 acid, succinic acid, alcohol, and glycerine. 



From the time of Fabroni, onwards, it has been 

 admitted that the agent by which this surprising 

 rearrangement of the particles of the sugar is- 

 effected is the yeast. But the first thoroughly 

 conclusive evidence of the necessity of yeast for 

 the fermentation of sugar was furnished by 

 Appert, whose method of preserving perishable 

 articles of food excited so much attention in 

 France at the beginning of this century. Gay- 

 Lussac, in his " Memoire sur la Fermentation," l 

 alludes to Appert's method of preserving beer- 

 wort uiifermented for an indefinite time, by 

 simply boiling the wort and closing the vessel 

 in which the boiling fluid is contained, in such 

 a way as thoroughly to exclude air; and he 

 1 Antialcs dc Ohimie, 1810. 



