52 ORIGIN AND ACTION OF HUMUS. 



formations, whether the Vital Principle, Increase 

 of Temperature, Light, Galvanism, or any other in- 

 fluence, the act of transformation is a purely che- 

 mical process. Combination and Decomposition can 

 take place only when the elements are disposed to 

 these changes. That which chemists name affinity 

 indicates only the degree in which they possess this 

 disposition. It will be shown, when considering 

 the processes of fermentation and putrefaction, that 

 every disturbance of the mutual attraction subsist- 

 ing between the elements of a body gives rise to a- 

 transformation. The elements arrange themselves 

 according to the degrees of their reciprocal attrac- 

 tion into new combinations, which are incapable of 

 further change, under the same conditions. 



The products of these transformations vary with 

 their causes, that is, with the diiferent conditions 

 on which their production depended; and are 

 as innumerable as these conditions themselves. 

 The chemical character of an acid, for example, 

 is its unceasing disposition to saturation by means 

 of a base ; this disposition differs in intensity in 

 different acids ; but when it is satisfied, the acid 

 character entirely disappears. The chemical cha- 

 racter of a base is exactly the reverse of this, but 

 both an acid and a base, notwithstanding the great 

 difference in their properties, effect, in most cases, 

 the same kind of transformations. 



Hydrocyanic acid and water contain the elements 

 of carbonic acid, ammonia, urea, cyanuric acid, 



