178 MANURE. 



During this time four eggs were laid, whose 



shells weighed, ..... 

 And contained phosphate of lime, 



Carbonate of lime, . . . . ; 



Gluten, 



The excrements during the same time, gave 

 of ashes, ..... 



Composed of carbonate of lime, . 



Phosphate of lime. 



Silica, 



Thus voiding in eggs and excrements. 



Carbonate of lime, 



Phosphate of lime. 



Now this is 17.2265 grains of silica less; and in round 

 numbers, 110 grains of phosphate, and 315 grains of carbon- 

 ate of lime more than the food eaten contained. Probably 

 in all such experiments, where confined to food different from 

 usual, and deprived of their customary habits, all animals 

 draw upon, and, in such cases, may be said to eat themselves. 

 The daily amount of bone-dust, however, which one hen thus 

 produces in her various droppings, is about 18^ grains, and 

 of carbonate of lime, 3.9 or an annual amount in round 

 numbers, of these two salts, of 1 pound and 3 ounces. Esti- 

 mating the salts only, it is found that the agricultural value 

 of a single hen per annum, equals the salts contained in sev- 

 eral bushels of wheat. This places in a strong light, the 

 very great effects produced by a spoonful of guano, to a hill 

 of corn. In Belgium, the annual value of the dung of 400 

 or 500 head of pigeons, much used in manuring flax, is $25 

 to |30. Under the name of columbine^ pigeons' dung is 

 much used in the north of France, and it is stated by Dumas, 

 that the annual droppings of six to seven hundred pigeons 



