FERMENTATION OF SUGAR. 313 



CHAPTER V. 



FERMENTATION OF SUGAR. 



The peculiar decomposition, which sugar suffers, 

 may be viewed as a type of all tKe transformations 

 designated fermentation.* 



Thenard obtained from 100 grammes f of cane- 

 sugar 0-5262 of absolute alcohol. 100 parts of sugar 

 from the cane yield, therefore, 103*89 parts of car- 

 bonic acid and alcohol. 'The entire carbon in these 

 products is equal to 42 parts, which is exactly the 

 quantity originally contained in the sugar. 



The analysis of sugar from the cane, proves that 

 it contains the elements of carbonic acicj and alco- 

 hol, minus 1 atom of water. The alcohol and car- 

 bonic acid produced by the fermentation of a certain 

 quantity of sugar, contained together one equivalent 

 of oxygen, and one equivalent of hydrogen, the ele- 

 ments, therefore, of one equivalent of water, more 

 than the sugar contained. The excess of weight in 

 the products is thus explained most satisfactorily ; 

 it is owing, namely, to the elements of water having 

 taken part in the metamorphosis of the sugar. 



It is known, that 1 atom of sugar contains 12 

 equivalents of carbon, both from the proportions in 

 which it unites with bases, and from the composition 



* When yeast is made into a thin paste with water, and 1 cubic centi- 

 metre of this mixture introduced into a graduated glass receiver filled 

 with mercury, in which are already 19 grammes of a solution of cane- 

 sugar, containing I gramme of pure solid sugar; it is found, after the 

 mixture has been exposed for 24 hours to a temperature of from 20 to 

 25 C. (68-77 F.), that a volume of carbonic acid has been formed, 

 which, at 0° C. (32° F.) and an atmospheric pressure indicated by 076 

 metre Bar. would be from 245 to 250 cubic centimetres. But to this 

 quantity we must add 11 cubic centimetres of carbonic acid, with 

 which the 1 1 grammes of liquid would be saturated, so that in all 255 

 -259 cubic centimetres of carbonic acid are obtained. This volume 

 of carbonic acid corresponds to from 0503 to 0*5127 grammes by 

 weight. — L. 



t The gramme equals 15-4440 grains. 



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