MANURES. 27 



and of the alkalies soda and potassa, but chiefly the latter. 

 Now all these bodies, or the elements of these bodies, exist in 

 animal and vegetable manures; for these being animal and 

 vegetable substances, are resolved into carbon, hydrogen, 

 oxygen and nitrogen, with the intermixed earthy and other 

 bodies existing in the living plants. 



In supplying, therefore, animal and vegetable substances to 

 the soil in a decomposing state, we, in truth, supply the same 

 substances which enter into the composition of the living 

 plants. These substances indeed exist in the dead matter of 

 the manures, in states of combination different from those in 

 which they exist in the living vegetable. But still they are 

 present, and no doubt supply the nutritive matter which the 

 plants require in growing. 



Science has made known to us the truth, that the living 

 plant and the dead manure are resolvable into the same ele- 

 mentary substances; but experience has not the less taught the 

 husbandman in every age, that all animal and vegetable sub- 

 stances, mixed with the matter of the soil, tend to fertilize it 

 by affording nourishment to the plants which it produced. 



Vegetable and animal substances deposited in the soil, as is 

 shown by universal experience, are consumed during the pro- 

 cess of vegetation, and they can only nourish the plant by 

 affording solid matters capable of being dissolved by water; or 

 gaseous substances capable of being absorbed by the fluids in 

 the leaves of vegetables; but such parts of them as are ren- 

 dered gaseous, and pass into the atmosphere, must produce 

 comparatively small effect, for gases soon become diffused 

 through the mass of the surrounding air. 



The great object, therefore, ia the application of manure, 

 should be to make it afford as much soluble matter as possible 

 to the roots of the plant, and that in a slow and gradual man- 

 ner, so that it may be entirely consumed in forming its sap 

 and organized parts. Water is apparently the medium by 

 which all the matter of nutrition, in whatever form, is con- 

 veyed into the roots of plants, and without which, accordingly, 

 vegetation is never known to take place. Therefore it is, that 

 the substances which form animal and vegetable manures, be- 

 fore they can be made available as nutriment to plants, must 

 be rendered soluble in water. 



Till within a few years past, the state in which vegetable or animal matter 

 exists in the soil, and the changes through which it passes before being taken 

 up by the roots of the plant, were almost entirely unknown to chemists. Long 

 ago, however, KLAPROTH had discovered a peculiar substance in the elm tree, 

 which he denominated ulmin. More recently it was found by BRACONNOT in 

 starch, saw-dust, and sugar and by the distinguished Swedish chemist, BER- 

 ZELIUS, in all kinds of barks. SPRENGEL, and POLYDORE BOULLAY, have ascer- 

 tained, also, that it constitutes a leading principle in manures and soils. Hence 

 they called it Humin (or, as is generally written. Humus); but BERZELIUS adopts 



