274 PHYSIOLOGY AT THE FARM. 



The sheep's dung contains 



Water, 68.0 



Animal and vegetable matter, . . . 19.3 

 Saline matter or ash, 12.7 



100.0 



Pigs' dung is less fermentable than that of the cow. It has 

 a very unpleasant odour, so that when used alone as a manure 

 it communicates to the crop, and especially to the root crops, 

 the same offensive smell. It is said that when tobacco is 

 raised on soil manured with pigs' dung its leaves are unfit for 

 smoking ; but for crops not designed for food, such as hemp 

 and flax, it is an excellent manure. It is best employed, how- 

 ever, when mixed with the other manures of the farmyard.* 



Pigeons' dung, being much prized wherever it can be obtained 

 in quantity, has been repeatedly analysed. Its effect as a manure 

 depends on the proportion of soluble material therein present. 



Davy found 23 per cent of soluble matter, and after fermen- 

 tation only 8 per cent. Sprengel found 16 per cent in pigeons' 

 dung six months old. The soluble matter consists of uric acid 

 in small proportion, of urate, sulphate, and especially of car- 

 bonate, of ammonia, common salt, and sulphate of potash ; the 

 insoluble matter chiefly of phosphate of lime, with a little phos- 

 phate of magnesia, and a variable admixture of sand and other 

 earthy matters. t When exposed to moisture, recent pigeons' 

 dung undergoes fermentation, and thereby losing a portion of 

 its ammoniacal salts, becomes less valuable. 



Hens' dung runs to waste in poultry-yards, when by a little 

 care it might supply some of the uses of pigeons' dung. 



Goose-dung is less rich than hens' or pigeons' dung. The 

 injurious effects of goose-dung on grass is but temporary it 

 arises from its being too concentrated when applied. When 

 the weather is humid, or rain succeeds, it is innocuous ; and 



* Johnston, 'Agricultural Chemistry, pp. 682, 683. f Ibid., p. 668. 



