DAUBENY ON THE NITROGEN OF PLANTS. 265 



form may therefore be stated, as consisting in the extrica- 

 tion of hydrogen 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." 



Dependence of the nutritive Qualities of Plants on their JSTitrO' 

 gen; from Daubeny^s Lectures. 



(See page 139.) 



'*The dependence of the nutritive qualities of various 

 articles of food upon the proportion of nitrogen is well 

 shown in a recent memoir of Monsieur Boussingault,* who 

 gives, on the authority of the celebrated agriculturist Von 

 Thaer, a scale of the relative degree of nutriment afforded 

 by various plants to cattle, and then places by the side of it 

 a statement of the proportion of azote present in them, from 

 which it appears, that the nutritious quality of each bears 

 a pretty constant ratio to the quantity of nitrogen they 

 contain. 



"This may be seen by the following table : 



Equiv. 

 Ordinary hay . . 100 its azote being 001 18 



Red Clover 

 Beans 



Wheat- straw 

 Potatoes 

 Beet 

 Maize 

 Barley 

 Wheat . 



90 . . . 00176 



83 . . . 0-0141 



400 .. . 0-0020 



200 . . . 0-0037 



397 .. . 0-0026 



59 . . . 0-0164 



54 . . . 0-0176 



27 . . . 0-0213 



'*When we reflect, indeed, that animal matter, which so 

 abounds in nitrogen, is nevertheless derived, either directly 

 or indirectly, from vegetable, it follows, as a necessary 

 consequence, that existence can only be maintained by the 

 aid of those principles in plants, which contain a certain 

 proportion of the element alluded to. 



" * Annales de Chiraie, Vol. LXIII." 



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