NATURE OF FERMENTATION. 259 



hydrogen as the sugar of grapes, but two atoms 

 less of oxygen ; and it is highly probable that it is 

 produced from sugar of grapes, contained in those 

 plants, in precisely the same manner as indigo-blue 

 is converted into deoxidised white indigo. 



During the putrefaction of gluten, carbonic acid 

 and pure hydrogen gas are evolved; phosphate, 

 acetate, caseate, and lactate of ammonia being at 

 the same time produced in such quantity, that the 

 further decomposition of the gluten ceases. But 

 when the supply of water is renewed, the decom- 

 position begins again, and in addition to the salts 

 just mentioned, carbonate of ammonia and a white 

 crystalline matter resembling mica (caseous oxide) 

 are formed, together with hydrosulphate of am- 

 monia, and a mucilaginous substance coagulable 

 by chlorine. Lactic acid is almost always pro- 

 duced by the putrefaction of organic bodies. 



We may now compare fermentation and pu- 

 trefaction with the decomposition which organic 

 compounds suffer under the influence of a high 

 temperature. Dry distillation would appear to be a 

 process of combustion or oxidation going on in the 

 interior of a substance, in which a part of the carbon 

 unites with all or part of the oxygen of the com- 

 pound, while other new compounds containing a 

 large proportion of hydrogen are necessarily pro- 

 duced. Fermentation may be considered as a 

 process of combustion or oxidation of a similar kind, 

 taking place in a liquid between the elements of 



s2 



