Book II. APPLICATION OF MANURES. 241 



their dung. It is laid on as fresh as possible, and is found better the less it lias 

 fermented. . 



1 149. The dung of cattle, oxen, and cows, has been chemically examined by kmhof and 

 Thaer. They found that it contained matter soluble in water ; and that it gave in 

 fermentation nearly the same products as vegetable substances, absorbing oxygen, and 

 producing carbonic acid gas. 



1 150. The recent dung of sheep and of deer affords, when long boiled in water, soluble 

 matters wliich equal from two to three per cent, of their weight. These soluble sub- 

 stances, procured by solution and evaporation, when examined, contain a very small quan- 

 tity of matter analogous to animal mucus ; and are principally composed of a bitter 

 extract, soluble both in water and in alcohol. They give ammoniacal fumes by dis- 

 tillation, and appear to differ very little in composition. Some blades of grass were 

 watered for several successive days with a solution of these extracts ; they evidently be- 

 came greener in consequence, and grew more vigorously than grass in other respects 

 under the same circumstances. The part of the dung of cattle, sheep, and deer, not 

 soluble in water, appears to be mere woody fibre, and precisely analogous to the residuum 

 of those vegetables that form their food after they have been deprived of all their soluble 

 materials. 



1151. The dung of horses gives a brown fluid, which, when evaporated, yields a bitter 

 extract, which affords ammoniacal fumes more copiously than that from the dung of 

 oxen. 



1152. In the treatment of the pure dung of cattle, sheep, and horses, there seems no 

 reason why it should be made to ferment except in the soil, like the other pure dungs ; 

 or, if suffered to ferment, it should be only in a very slight degree. The grass, in the 

 neighbourhood of recently voided dung, is always coarse and dark green ; some persons 

 have attributed this to a noxious quality in unfermenting dung; but it seems to 

 be rather the result of an excess of food furnished to the plants. 



1 153. Street and road dung and the sweepings of houses may be all regarded as composite 

 manures ; the constitution of them is necessarily various, as they are derived from a num- 

 ber of different substances. These manures are usually applied in a proper manner, 

 without being fermented. 



1154. Soot, which is principally formed from the combustion of pit-coal or coal, 

 generally contains likewise substances derived from animal matters. This is a very 

 powerful manure. It affords ammoniacal salts by distillation, and yields a brown 

 extract to hot water, of a bitter taste. It likewise contains an empyreumatic oil. Its 

 great basis is charcoal, in a state in which it is capable of being rendered soluble by the 

 action of oxygen and water. This manure is well fitted to be used in the dry state, 

 thrown into the ground with the seed, and requires no preparation. 



Subsect. 3. Of the fermenting, preserving, and applying of Manures of Animal and 



Vegetable Origin. 



1155. On tlie management of organic manures depends much of their value as food to 

 plants. The great mass of manures procured by the cultivator are a mixture of 

 animal and vegetable matters, and the great source of supply is the farm or stable yard. 

 Here the excrementitious matter of horses, cattle, swine, and poultry, is mixed 

 with straw, haulm, chaff, and various kinds of litter. To what degree should this 

 be fermented before it is applied to the soil ? And how can it best be preserved when not 

 immediately wanted? 



1156. A slight incipient fermentation is undoubtedly of use in the dunghill; for, by 

 means of it a disposition is brought on in the woody fibre to decay and dissolve, when it 

 is carried to the land, or ploughed into the soil ; and woody fibre is always in great ex- 

 cess in the refuse of the farm. Too great a degree of fermentation is, however, 

 very prejudicial to the composite manure in the dunghill ; it is better that there should be 

 no fermentation at all before the manure is used, than that it should be carried 

 too far. The excess of fermentation tends to the destruction and dissipation of the most 

 useful part of the manure ; and the ultimate results of this process are like those of com- 

 bustion. It is a common practice amongst farmers to suffer the farm-yard dung to ferment 

 till the fibrous texture of the vegetable matter is entirely broken down ; and till 

 the manure becomes perfectly cold, and so soft as to be easily cut by the spade. Inde- 

 pendent of the general theoretical views unfavorable to this practice, founded upon the 

 nature and composition of vegetable substances, there are many arguments and 

 facts which show that it is prejudicial to the interests of the farmer. 



1157. During the violent fermentation which is necessary for reducing farm-yard 

 manure to the state in which it is called short muck, not only a large quantity of fluid, but 

 likewise of gaseous matter is lost ; so much so, that the dung is reduced one half, or two 

 thirds in weight ; and the principal elastic matter disengaged, is carbonic acid with some 

 ammonia ; and both these, if retained bv the moisture in the soil, as has been stated 



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