MILK IN DIFFERENT ANIMALS. 283 



portion than in woman's milk ; besides, while it has less sugar 

 it has more butter. The proportion of salts is greater, but the 

 excess chiefly affects the insoluble salts belonging to the 

 caseine, and therefore is the consequence of the presence of a 

 larger proportion of that proximate principle. 



Mares' milk is white, somewhat thick, and has a specific 

 gravity of 1.034 to 1.045. It contains 16 per cent of solid 

 residue ; it has a small proportion of caseine, a large amount of 

 fat, and a considerable proportion of sugar. 



Sheep's milk is thickish, white, and of an agreeable odour 

 and taste. Its specific gravity varies between 1.035 and 

 1.041. The solid constituents amount to 14.38 per cent, and 

 of these there are 4.02 of caseine, 4.20 of butter, 5.0 of sugar, 

 and 0.68 of salts. Compared with cows' milk, it appears to 

 contain less caseine and less butter, but more sugar of milk. 



Of the milk of the sow no account is to be met with. 



The milk of the bitch is somewhat thick, and on being 

 heated it becomes much thicker even without coagulation. 

 When the animal has been fed only on vegetable food the 

 milk is neutral, or has a faintly-alkaline reaction. When 

 animal food has been allowed, the milk has an acid reaction, 

 while the specific gravity varies from 1.033 to 1.036. It con- 

 tains, then, from 17.46 to 22.48 per cent of solid constituents, 

 of which from 8 to 11 per cent are caseine, and from 6.84 to 

 10.95 butter, besides which there is a small quantity of sugar 

 of milk. When the food is mixed, there is more butter and 

 also more sugar. The ash sometimes contains as much as 3 

 per cent of insoluble salts. 



According to Boussingault, a cow yields on an average, for 

 every thousand parts of her weight, 10.4 parts by weight of 

 milk. 



Table of the proportions of the several proximate principles 

 and salts in the milk of the cow : 



