PART II. 



OF THE CHEMICAL PROCESSES OF FERMENTATION, 

 DECAY, AND PUTREFACTION. 



CHAPTER I. 



CHEMICAL TRANSFORMATIONS. 



Woody fibre, sugar, gum, and all such organic 

 compounds, suffer certain changes when in contact 

 with other bodies ; that is, they suffer decomposition. 



There are two distinct modes in which these de- 

 compositions take place in organic chemistry. 



When a substance composed of two compound 

 bodies, crystallized oxalic acid for example, is brought 

 in contact with concentrated sulphuric acid, a com- 

 plete decomposition is effected upon the application 

 of a gentle heat. Now crystallized oxalic acid is a 

 combination of water with the anhydrous acid ; but 

 concentrated sulphuric acid possesses a much greater 

 affinity for water than oxalic acid, so that it attracts 

 all the water of crystallization from that substance. 

 In consequence of this abstraction of the water, an- 

 hydrous oxalic acid is set free ; but as this acid can- 

 not exist in a free state, a division of its constitu- 

 ents necessarily ensues, by which carbonic acid and 

 carbonic oxide are produced, and evolved in the 

 gaseous form in equal volumes. In this example, 

 the decomposition is the consequence of the removal 

 of two constituents (the elements of water), which 

 unite with the sulphuric acid, and its cause is the 

 superior affinity of the acting body (the sulphuric 

 acid) for water. In consequence of the removal of 



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