PART II. 



OF THE CHEMICAL PROCESSES OF FERMENTATION, DECAY' 

 AND PUTREFACTION. 



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 

 decompositions take place in organic chemistry. 



When a substance composed of two compound 

 bodies, crystallised oxalic acid for example, is 

 brought in contact with concentrated sulphuric 

 acid, a complete decomposition is effected upon the 

 application of a gentle heat. Now crystallised 

 oxalic acid is a combination of water with the anhy- 

 drous acid ; but concentrated sulphuric acid pos- 

 sesses 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 abstrac- 

 tion of the water, anhydrous oxalic acid is set free ; 

 but as this acid cannot exist in a free state, a divi- 

 sion of its constituents 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 con- 

 sequence of the removal of two constituents (the 



