ATTEm>mG THE FORMATION OF COAL, &c. 253 



bon with 22 atoms of water. There can be no doubt, how- 

 ever, that the elements are intimately united with each other, 

 and do not exist as mere carbon and water; still this extreme 

 simplicity of constitution was designed for an allwise pur- 

 pose, and greatly facilitates the necessary changes which 

 must take place on the death of an organic body. 



When such a body dies, and is exposed to the action of 

 the air, it is probable that 2 atoms of the atmospheric oxy- 

 gen unite with 2 atoms of the hydrogen of the plant, and 

 form 2 atoms of water, which are eliminated, whilst 2 atoms 

 of the oxygen of the organic body being thereby Uberated, 

 immediately unite with one atom of the carbon of the 

 plant, and form one atom of carbonic acid, which is also 

 eliminated; so that, for every atom of carbon removed, 2 

 atoms of hydrogen and 2 atoms of oxygen are also displaced, 

 and in time nothing but carbon would remain, were the 

 process to go on in the atmosphere freely and undisturbed. 

 When the process is about half completed, what is called 

 vegetable mould, or humus, is formed. 



When a vegetable body decomposes under water, the 

 circumstances in which it is placed being different to its 

 condition when freely exposed to the atmosphere, the pro- 

 cess and order of decomposition are also very different. It 

 decomposes with limited access of air, and in contact with a 

 body (water) itself susceptible of decomposition in the 

 presence of decomposing organic matter. Water has the 

 property of absorbing a certain quantity of oxygen from the 

 atmosphere. 100 cubic inches of water at a temperature of 

 60° Faht., and under a pressure of 30 inches mercury, will 

 absorb about Z^ cubic inches of oxygen. It is well known 

 that all plants in a living state absorb oxygen united to 

 carbon or carbonic acid; and hence it is, that the herbage 

 on the brow of a hill, on which a rill of water trickles, looks 

 so bright and green, and fresh and vivid, from the incessant 

 supply of oxygen to its roots, in the best form for oxidizing 



