On the Application of Manures, 253 



of these two ingredients, as is shown in the following table of 

 M. Pajen:— 



Ligneous Bodies. 



Carbon. 



Hyd 



rogen. 



Oxygen. 



Incrusting 

 Matter. 



Incrusting matter of the wood .... 



53 



76 



6 



00 



40 



20 



100 







90 



6 



07 



41 



03 



90 





53 



85 



G 



00 



41 



15 



89 





51 



92 



5 



96 



42 



12 



82 





50 



00 



6 



20 



43 



SO 



61 



Ditto, according to Gay-Lussac and Thenard 



51 



45 



5 



82 



42 



73 







49 



25 



6 



10 



. 44 



65 



52 





44 



90 



6 



10 



49 



00 



00 



This then proves that, in the formation of the matter which 

 incrusts and fortifies the walls of the cellular tissue in wood, 

 though not in that of the cellular tissue itself, a decomposition of 

 water must have taken place ; since the 1 per cent, of hydrogen 

 which Paven has found in excess can only have arisen in this 

 manner. 



This increase of hydrogen becomes still greater when in the 

 progress of vegetation the plant begins to secrete oils, camphors, 

 and other analogous bodies — products which, it is to be remarked, 

 abound most within the tropics, where the light of the sun is most 

 intense. 



Hence the decomposition of water^ no less than that of carbonic 

 acid, seems due to solar influence, and accordingly the greater 

 sweetness of subacid fruits in a warm than in a cold summer 

 arises from the transformation of a larger amount of tartaric or 

 other vegetable acids into sugar, owing to that separation of 

 oxygen from the former which is accomplished by the agency of 



The process of assimilation of plants in its most simple form 

 may therefore be stated as consisting in the extrication of hydro- 

 gen from water, and of carbon from carbonic acid, in consequence 

 of which one of three things must happen' — either all the oxygen 

 of the water and of the carbonic acid are separated, as in those 

 bodies which, like caoutchouc, volatile oils, &c., consist of nothing 

 else but carbon and hydrogen ; or, secondly, only a part of it is 

 exhaled, as in the case of the incrusting matter of wood, and in 

 sugar ; or, thirdly, that belonging to the carbonic acid alone is 

 decomposed, whilst the water remains, as in starch and cellular 

 tissue. 



But there is yet another ingredient which is present, although 

 generally in minute proportions, in many vegetable principles, 

 and which therefore must be furnished to them from without, in 



