148 On the ylpjj/icatlon 



seen, that the proportion of g-luten to starch, as well as the aggre- 

 gate amount of the crop itself, is augmented by manuring the soil 

 with those materials which are richest in ammonia, such, for in- 

 stance, as blood, pigeons' dung, &c. 



Now the practical inference I would deduce from this is, first, 

 that it must be of the highest possible importance to preserve in 

 tanks, or at least to detain, by the admixture of absorbent ma- 

 terials, the liquid manure which is so often allowed to run to 

 waste on your dunghills ; and, secondly, that it might be worth 

 trying whether a better distribution of the manure at the disposal 

 of the farmer might not be made, by adding the solid portion of 

 his dung-heap, which is richest in the phosphates, to the turnip 

 crop, and reserving the drainings, to be scattered, after the Bel- 

 gian fashion^ in water-carts, over the ground intended for his 

 wheat. 



May not this also serve to explain, why the nitrates of soda and 

 of potass are in general found to be less serviceable to the 

 turnip crop than to the cereal and other grasses ? 



Whatever other function these salts may discharge in agricul- 

 ture, there is one at least which will probably not be denied to 

 them, that, I mean, of furnishing an abundant supply of nitrogen 

 to the crop. This arises from the decomposition of their nitric 

 acid by the organs of the plant through the agency of light; and 

 as it requnes a greater expenditure of chemical force to resolve 

 into its elements a compound so stable as nitric acid than to effect 

 the same with ammonia, we may understand why the influence of 

 these manures should be so capricious in climates like our own, 

 where the solar intensity is often interrupted ; and why Nature 

 has provided that the products of animal decay should present 

 themselves most commonly, in the form of nitric acid in hot 

 countries, and in that of ammonia in cold ones. 



Now it appears from some recent researches of M. Pay en, in 

 France,* that the rudiment of every vegetable tissue, the sub- 

 stance ])rimarily produced in all instances during the development 

 of the seed or bud, is a matter containing azote, and having some 

 resemblance to the material which constitutes the muscular fibre 

 of animals. 



Access, therefore, to a certahi amount of nitrogen is a necessary 

 condition for incipient vegetation ; and a supply of animal manure, 

 or of some substitute for it, such as the nitric salts, must clearly 

 be indispensable for the rapid development of every kind of plant. 

 But it is equally manifest, that if a manure rich in nitrogen merely 



" In the cambium, preceding the formation of the vegetable, appears 

 first a granular contractile substance, containing azote. It fills the cells, 

 the membranes of which are composed of carbon, oxvgen, and hydrogen 

 only."— Comptes Rendu.s 1839, vol. ii., p. 3Q9. 



