56 . CHYMISTRY APPLIED TO AGRICULTURE. 



to agriculture, it is necessary at least to dig a deep ditch 

 to receive all the juices which flow from the dunghill, in 

 order that they may be used in the spring upon the corn 

 or grass lands ; or they may be preserved to water the 

 grass lands with, after the first mowing. A large cask, 

 fixed upon a small cart, and which can be filled by means 

 of a hand pump, is sufficient for this purpose. Beneath 

 the tap of the cask must be fitted a narrow chest about 

 four feet long, with the bottom pierced with holes, through 

 which the liquor may be scattered. This mode of water- 

 ing, when used after mowing, produces wonderful, effects 

 upon the crop of the following year. 



Before deciding upon the question, whether dung and 

 litter should or should not be made to ferment, it is neces- 

 sary to take into consideration the nature of the soil to be 

 manured. If this be compact, clayey, and cold, it is 

 better that fermentation should not have taken place, as 

 two effects will be produced by the application of the 

 manure in an undecomposed state. In the first plape it 

 will improve the soil by softening and dividing it, so as to 

 render it permeable by air and water ; and in the next 

 place it will, whilst undergoing the successive processes 

 of fermentation and decomposition, warm the soil. If, on 

 the contrary, the soil be light, porous, calcareous, and 

 warm, the thoroughly fermented manure, or short muck, 

 as it is called by farmers, is preferable, because it gives 

 out less heat, and instead of opening the earth, already 

 too porous, to the filtrations of water, it moderates the 

 flow of that fluid. Long experience has made these truths 

 known to observing, practical farmers. 



When it is required to apply dung to any particular 

 kind of soil, it is necessary that it should be used accord- 

 ing to a knowledge of its qualities. The dung of animals 

 bearing wool is the warmest; next, that of horses; whilst 

 that of cows and oxen contains the least heat of any. 



Soft or fluid animal substances change the most easily; 

 and the progress of their decomposition is rapid in pro- 

 portion to the diminution of the quantity of earthy salts 

 contained in them. Their decomposition produces an 

 abundance of ammonial gas. This circumstance distin- 

 guishes them from vegetable substances, the decomposition 

 of which gives rise to the production of that gas, only as 

 far as they contain a small portion of albumen. It is par- 

 ticularly to the developement of ammonial gas, which, 



