HINDRANCES AND HELPS 



away place, and asks what is in it ; he can tell 

 upon examination, and if, after such exam- 

 ination he finds it to possess a large percentage 

 of soluble phosphoric acid, he will advise its 

 use as a manure, and can promise that it will 

 contribute largely to the vigor of a wheat crop ; 

 all this — not simply because phosphoric acid is 

 a constituent part of the grain, but because he 

 knows that other dressings containing a like 

 element, have invariably so contributed; the 

 fact being established by repeated farm-trials. 

 But it is not a result determinable, so far as a 

 field-crop is concerned, by simple chemical in- 

 vestigation; nor could it be so determinable, 

 unless you could establish the crop and feed it, 

 under those Conditions of alienation from all 

 other influences, by which or under which 

 alone, the chemist is enabled to establish the 

 severity of his conclusions. 



The power of the chemist to decompose, to 

 unravel, to tear in pieces, and to name and 

 classify every separate part, is something won- 

 derful ; but his power to combine is less mirac- 

 ulous. Give him all the carbonic acid in the 

 world and he cannot make us a diamond, or 

 a lump of charcoal. And when, with the natu- 

 ral combination is associated a vital principle, 

 (as in plants,) controlling, amplifying, decom- 



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