64 CHTMISTRY APPLIED TO AGRICULTURE. 



as manure contain mucilage, gelatine, oils, sugar, starchy 

 extractive matter, and often albumen, acids, salts, &c, 

 with an abundance of fibrous matter, insoluble in water. 



The diflferent substances afforded by animals, including 

 all their excretions, are gelatine, fibrine, mucus, fat, albu- 

 men, urea, uric and phosphoric acids, and some salts. 



The greatest part of the substances, constituting ani- 

 mals and vegetables, are soluble in water ; and it is evi- 

 dent that in that state they can be employed as manures 

 without {wevious fermentation ; but it is necessary, that 

 those which contain much insoluble matter should be 

 decomposed by fermentation, because by that process their 

 nature is changed, and they form new compounds, which, 

 being capable of solution, can pass into the organs of 

 plants. 



Messrs. Gay-Lussac and Thenard have obtained, by an 

 analysis of the woody fibre, oxygen, hydrogen, and es- 

 pecially more carbon, than from any other part of the 

 plant, and they have determined their several proportions. 

 We know that fermentation carries off much carbon ; it 

 is then evident that, by causing the fermentation of the 

 vegetable fibre, the principle which forms its distinguish- 

 ing characteristic will be gradually diminished, and that 

 it will no longer be a body insoluble in water. It is in 

 this manner that woody plants and the driest leaves are 

 converted into manure. 



But as all the solid parts of plants contain fibres which 

 cannot be rendered soluble in water, but by a long period 

 of fermentation ; and as it is in the fibre that carbon, a 

 principle so necessary to vegetation, chiefly exists, the 

 fermentation of plants is indispensable to the procuring of 

 the best part of their manure. 



The custom of appropriating some crops whilst green 

 to the manuring of the ground, may perhaps be objected 

 to ; but I have observed, that in that case the plants are 

 buried in the earth at the time of flowering ; and whilst 

 they are succulent, and their fibres soft, and but little 

 formed ; and that warmth and the action of water in the 

 earth was sufficient to decompose them : this would not 

 take place if the stalks were dried and hardened by the 

 formation of the grain. 



The dung of quadrupeds may be mixed advantageously 

 with the earth at the time of being taken from the 

 ■table, if it contain no litter ; but if it does, it appears to 



