ASSIMILATION OF HYDROGEN, 



CHAPTER IV. 



On the Assimilation of Hydrogen. 



The atmosphere contains the principal food of plants in the 

 form of carbonic acid, in the state, therefore, of an oxide. The 

 solid part of plants (woody fibre) contains carbon and the consti- 

 tuents of water, or the elements of carbonic acid, together with a 

 certain quantity of hydrogen. It has formerly been mentioned 

 that water consists of the two gases, oxygen and hydrogen. We 

 can conceive the wood to arise from a combination of the 

 carbon of the carbonic acid with the elements of water, under 

 the influence of solar light. In this case, 72-35 parts of oxygen, 

 by weight, must be separated as a gas for every 27-65 parts of 

 carbon assimilated by a plant ; for this is the composition of car- 

 bonic acid in 100 parts. Or, what is much more probable, 

 plants, under the same circumstances, may decompose water, in 

 which case the hydrogen would be assimilated along with car- 

 bonic acid, whilst its oxygen would be separated. If the latter 

 change takes place, 9*77 parts of hydrogen must unite with 100 

 parts of carbonic acid in order to form woody fibre, and the 

 7235 parts by weight of oxygen, which was in combination with 

 the hydrogen of the water, and which exactly corresponds in 

 quantity with the oxygen contained in the carbonic acid, must 

 be separated in a gaseous form.* 



Each acre of land, producing 10 cwts. of carbon, gives 



* As far as regards the final results, it is a matter of perfect indiffer- 

 ence to which of these views we accord the preference. Hence we will 

 use both occasionally. The decomposition of carbonic acid, as well as 

 that of water, must be supposed in the formation of those compounds 

 in which oxygen is either entirely absent or insufficient to form water 

 with the hydrogen. 



