424 Chemical Properties of Animal Fluids. [Dec. 



the form of a grey powder, which fused with soda produced a 

 transparent glass, and which by the decomposition of the glass 

 was converted into the gelatinous state. The water we drink, 

 and which supplies the continual waste of that element by per- 

 spiration and by urine, always contains silex, which appears not 

 to separate from it in the body, and which thus makes its exit in 

 the same state in which it entered. It is evident that this earth 

 should be found dissolved in the other animal fluids, and that the 

 quantity must vary according to the quantity contained in the 

 water used as beverage. 



Milk. 



My experiments have chiefly been made on the milk of the 

 cow. The composition of this fluid is exceedingly analogous to 

 that of blood. It consists, like the blood, of a chemical solu- 

 tion, and an admixture of undissolved matter suspended in it. 

 By exposing milk for some days in a shallow vessel to the tem- 

 perature of 32° Fahr. I separated from it the cream as com- 

 pletely as I could. The lower portion of milk, decanted by a 

 hole at the bottom of the vessel, had a specific gravity of 1 "033, 

 and yielded by analysis the following constituents : — 



Water 92875 



Cheese, with a trace of butter .... 28*00 



Sugar of milk 35-00 



Muriate of potash 1*70 



Phosphate of potash 0'25 



Lactic acid, acetate of potash, with \ fi „- 



a trace of lactate of iron J 



Earthy phosphates 0*30 



1000-00 



Cream contains the emulsive matter which is not dissolved, 

 more concentrated and mixed with a portion of milk. This 

 emulsion is easily decomposed by agitation, absorbs oxygen, and 

 the butter separates : the milk becoming by this operation more 

 acid than it was at first. I found that cream of the specific 

 gravity 1-0244 was composed of • 



Butter 4-5 



Cheese 3*5 



Whey !)2*0 



As 32 parts whey contain 4 # 4 sugar of milk and salts, it follows 

 that cream "contains about 12-5 per cent, of solid matter. 



It is very remarkable that scarcely any other alkali than potash 

 is found in milk. I have burnt a quantity of dried milk, and 

 have dissolved the muriate of the ashes in spirit of wine; and the 



