DIFFERENCE OF FERMENTATION AND PUTREFACTION. 321 



the same number of equivalents of carbon and hydro- 

 gen 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 con- 

 verted into deoxidized 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 decompo- 

 sition begins again, and in addition to the salts just 

 mentioned, carbonate of ammonia and a white crys- 

 talline matter resembling mica (caseous oxide) are 

 formed, together with hydrosulphate of ammonia, 

 and a mucilaginous substance coagulable by chlorine. 

 Lactic acid is almost always produced by the putre- 

 faction of organic bodies. 



We may now compare fermentation and putrefac- 

 tion with the decomposition which organic com- 

 pounds suffer under the influence of a high tempera- 

 ture. 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 compound, 

 while other new compounds containing a large pro- 

 portion of hydrogen are necessarily produced. Fer- 

 mentation may be considered as a process of com- 

 bustion or oxidation of a similar kind, taking place 

 in a liquid between the elements of the same matter^ 

 at a very slightly elevated temperature ; and putre- 

 faction as a process of oxidation, in which the oxy- 

 gen of all the substances present comes into play. 



