CHARCOAL ABSORBING GASES. 21 



solves very readily in water. By absorption from 

 the atmosphere, by the decay of organic substances 

 in the soil, etc., it finds its way into the soil water, 

 and with it into the plant. Besides this direct use- 

 fulness as plant food, it has the indirect value of 

 giving to the water which holds it in solution an 

 increased power of dissolving other mineral sub- 

 stances, and of those making them available for 

 plant food. 



Although it is true that charcoal, being insoluable 

 in water, can not directly enter into the circulation 

 of plant sap, and that plants can depend upon the 

 atmosphere for almost the whole of their carbon 

 supply, if neccessary; yet the application of pulver- 

 ized charcoal, or other finely- divided carbon in its 

 elementary form, shows often remarkable effects 

 upon plant growth. This is to be explained otherwise 

 than on the theory that the elementary carbon can 

 be utilized as plant food. Charcoal might be re- 

 garded as the skeleton of the wood from which it 

 was prepared. A large portion of the substance of 

 the wood has been driven off by heat, but the form, 



the structure, still remains, and con- 

 Ab8orbine*Ga8eB. sequently the charcoal skeleton is 



exceedingly porous. Like other 

 porous substances, it possesses the power of absorb- 

 ing and condensing gases. Hop growers know 

 what a large bulk of dried hops can be condensed 

 into the space of a bale by means of a good hop- 

 press; but a hop-press is next to powerless when 

 you compare it with charcoal. This substance will 

 absorb and condense in itself ninety times its own 

 bulk of ammonia, thirty-five times its bulk of car- 

 bonic acid, and other gases proportionately. It 

 catches plant foods, and brings and holds them for 



