\SSIMILATION OF HYDROGEN. 



on the contrary, is only decomposable by violent chemical 

 action. 



Most vegetable structures contain hydrogen in the form of 

 water, which can be separated as such, and replaced by other 

 bodies ; but the hydrogen essential to their constitution cannot 

 possibly exist in the state of water. 



All the hydrogen necessary for the formation of an organic 

 compound is supplied to a plant by the decomposition of water. 

 The process of assimilation, in its most simple form, consists in the 

 extraction of hydrogen from water, and of carbon from carbonic 

 acid, in consequence of which, either all the oxygen of the 

 water and of the carbonic acid is separated, as in the formation 

 of caoutchouc, the volatile oils containing no oxygen, and other 

 similar substances, or only a part of it is exhaled. 



The known composition of the organic compounds most gene- 

 rally present in vegetables, enables us to state in definite propor 

 tions the quantity of oxygen separated during their formation. 



36 eq. carbonic acid and 22 eq. hydrogen derived ) y_. Fibre * 



from 22 eq. water ) H - 



with the separation of 72 eq. oxygen. 

 3G eq. carbonic acid and 3G eq. hydrogen derived ) _ c W p. ,_ 

 from 36 eq. water ----- ) 



with the separation of 72 eq. oxygen. 

 36 eq. carbonic acid and 30 eq. hydrogen derived ) __ i e/ arc A 



from 30 eq. water y 



with the separation of ^2 eq. oxygen. 

 36 eq. carbonic acid and 1,6 eq. hrlroge.i derived ) .— j^ ann i c ji c {^ 



from 16 eq. water ) 



with the separati y\\ of 64 eq oxygen. 

 36 eq. carbonic acid and 13 eq. hydrogen derived j __ ^ artar i c j[ c jd 

 from 18 eq. water -----$ 



with the separation of 45 eq. oxygen. 

 36 eq. carbonic acid and IS eq. hydrogen derived > _ j^f a n c j a( j 



from IS eq. water ) 



with the separation of 54 eq. oxygen. 



* It is evident that both carbonic acid and water must be decomposed 

 to yield woody fibre of the above composition, C3 6 H2 2 2 2 ; that is, if 

 water is here decomposed. For 22 eq. of water can only yield 22 eq. of 

 oxygen ; and, therefore, supposing all the water to be decomposed, 25 of 

 the 36 eq of carbonic acid must also be decomposed, to yield, with the 

 oxygen of the 22 eqs. of water, 72 eq. of oxygen. The remaining 11 eqs. 

 of carbonic acid with the carbon of the 25 eq. decomposed, and the 22 eqs 

 of hydrogen will then yield the residue C3 6 H2 2 2 2. 



