SCIENCE OF AGRICULTURE. 115 



power to decompose the earths that contain it, than 

 those of wheat have. And as by reference to the an- 

 nexed table of soils analyzed by Professor Hitchcock, 

 it will be seen that all our soils contain a larger quan- 

 tity of the sulphate and phosphate of lime, than any 

 one crop of either of these kinds of grain contains, 

 it may follow, that oats from their greater power of 

 searching for, and more easily digesting it, will 

 flourish better in a soil poor in its percentage of 

 lime than wheat will in the same soil. And as the 

 nourishment of plants is probably decomposed, cook- 

 ed, or prepared, in some measure, by currents of 

 galvanic electricity exterior to the roots themselves, 

 a very important question is suggested for our con- 

 templation in regard to mixed crops. May not the 

 roots of one kind commingling with roots of another 

 of stronger powers appropriate to themselves, in 

 some measure, the food prepared for their neighbors? 

 If so, it will account philosophically for what is con- 

 sidered a fact in some parts of our commonwealth, 

 viz: that wheat does better sown mixed with oats, 

 than it does alone. It will be seen by reference to 

 the foregoing table, oats must have vastly greater 

 power to decompose not only the salts of lime, but 

 silica, alumina and oxyd of iron likewise. Here 

 another thought occurs worthy of attention. Will 

 not agricultural chemistry by and by enable us to 

 understand, by teaching us the analysis of vegetables, 

 precisely how much one crop exhausts a soil of cer- 

 tain constituents more than another, and what must 

 be restored to that soil to enable it to produce 

 another crop of the same vegetable equal to the 

 preceding. And also what other crops would be 

 likely to do well on the same soil without the resto- 

 ration of such constituents? 



A still more important constituent of soils and 

 vegetables, of which we^have as yet only incidentally 

 spoken is carbon. Carbon enters largely into a 

 great variety of substances, mineral and vegetable, 

 assumes every mode or form in which matter exists. 



