34 ELFMENTS OF 



cess, and of which all the principles have entered into 

 new combinations. 



It is certainly a matter of indifference whether we 

 employ excrements, ashes, or bones, in carrying out the 

 principle of restoring to the soil those substances which 

 have been taken from it by the previous crop. But, 

 unless we know accurately what are those matters that 

 have been actually removed, how is it possible to supply, 

 otherwise than at random guess, the deficiency? Fer- 

 mented manure may be really useful, if no nitrogen be 

 demanded. A time will come when fields will be ma- 

 nured with saline solutions, with the ashes of burnt 

 straw, or with salts of phosphoric acid prepared in chemi- 

 cal manufactories. The same mixed mass of materials 

 may be useful in one state, less so in another and under 

 other circumstances. A knowledge of the actual wants 

 of the land, and of the exact composition of the proposed 

 manure, is obviously necessary to enable the farmer 

 to adapt the one to the other as a requisite and fitting 

 remedy. If our object be the development of the seeds 

 of plants, we know they contain nitrogen. Our manure 

 then must be rich in this material. If, by fermentation, 

 ammonia be formed in the manure — if it become dry, 

 rotten, and nearly devoid of smell, having lost its pre- 

 vious heat — although it may cut better with the spade, 

 we may be sure it has lost its nitrogen, and, conse- 

 quently, as far as our object is concerned, (the nutriment 

 of the seed.) nearly lost its utility. The leaves, which 

 by their action on the air, nourish the stem and woody 

 fibre — the roots, from which the leaves are formed — 

 in short, every part of tlie structure of a plant — contains 

 nitrogen in small and varying proportions. But the 

 ijeeds are always rich in nitrogen. 



The most imjiortant object, then, of farming opera- 

 lions, at least as far as grain is concerned, is the supply 

 of nitrogen to grain plants in a state capable of being 

 taken up by them — the production, therefore, of manures 

 containing the most of this element. Gypsum and ni- 

 trate of soda are as properly termed manures, as farm- 

 yard dung, bone-dust, or night-soil; but our present 



