SCIENCE OF AGRICULTURE. 127 



of lime. Experiments are wanting to prove the re- 

 lative value of lime and ashes. I should not deem 

 it extravagant to say, that a bushel of ashes is equal 

 to a cask of lime. The alkalies and their salts act 

 more powerfully than any other substance, in solving 

 and converting geine. Lime in all its forms ranks 

 next. These produce always decided beneficial ef- 

 fects. The alkalies never fail. Ashes show their 

 effects at once, due to the alkaline part, while their 

 carbonate of lime produces more permanent effect. 

 Lime, from peculiar states of the soil, may not show 

 any immediate good result, but ultimately, this result 

 is sure to follow. Permanent barrenness never is 

 produced by the free use of carbonates. It surely 

 follows the free use of all other salts, yet in small 

 doses, they all and ever act beneficially, whenever 

 their bases, combined with carbonic acid, would be 

 beneficial. 



"But how do the elements of soil act? As I have 

 stated in the report of Professor Hitchcock, by form- 

 ing galvanic batteries with the roots of living plants. 

 The most active element in the pile is the root. The 

 soil, like the rocks from which it is derived, is slow- 

 ly acted on by atmospheric agents. The effect of 

 this action annually is imperceptible. 



"A single plant in one season will effect a greater 

 amount of decomposition of a given portion of soil, 

 than that produced by all the atmospheric agents in 

 many years. The galvanic agency of plants is not 

 confined to the soil, in immediate contact with their 

 roots. It extends from these, in every direction, to 

 undetermined distances. Hence there is a transfer, 

 as is usual in galvanic decompositions, of substances 

 quite remote from the plant. The whole plant con- 

 tributes to this galvanic agency. It never exists in 

 full force, perhaps not at all, till the plant has push- 

 ed above ground — acted on by air and light. 



"The soil, as we have explained, consists almost 

 wholly of silicates, though it has been proved, that 

 carbonic acid slowly decomposes these, and an argu- 



