HINDRANCES AND HELPS. 227 



is concerned, by simple chemical investigation ; nor 

 could it be so determinable, unless you could estab 

 lish 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 estab 

 lish the severity of his conclusions. 



The power of the chemist to decompose, to un 

 ravel, to tear in pieces, and to name and classify every 

 separate part, is something wonderful ; but his power 

 to combine is less miraculous. Give him all the car 

 bonic-acid in the world and he cannot make us a 

 diamond, or a lump of charcoal. And when, with the 

 natural combination is associated a vital principle, 

 (as in plants), controlling, amplifying, decomposing 

 at its will, his power shrinks into still smaller dimen 

 sions. Faithful and long-continued observation of 

 the mysterious processes of nature, will alone justify 

 a theory of plant-nutrition. A large part of this ob 

 servation is supplied by the history of farm-ex 

 periences, and another part is supplied by the earnest 

 investigations of special scientific inquirers. Where 

 the two tally and sustain each other, one may be 

 sure of standing upon safe ground. But where they 

 are antagonistic, one has need to weigh conflicting evi 

 dence well, not presuming hastily that either practical 

 experience, or a special science h s, as yet, a mo 

 nopoly of all the truths which lie at the base of tho 



