2Q2 PHYSIOLOGICAL CHEMISTRY. 



about 0.7 per cent in the mean. This amount appears small, 

 but still it is of the highest importance, as it makes up between 

 5 and 6 per cent of the total solids of the milk. The composi- 

 tion of milk ash has been the subject of many investigations. 

 While it cannot represent exactly the condition of the inor- 

 ganic substances in the original milk, the agreement is an ap- 

 proximate one and is probably near enough for practical pur- 

 poses. In obtaining ash for analysis, sulphur and phosphorus 

 in organic combination are thrown into oxidized form and 

 combined as salts, sulphates and phosphates, in which form 

 we find them in our subsequent tests. The following figures 

 from Konig represent the composition of milk ash as the 

 mean of 9 analyses : 



Per Cent. 



K 2 O 24.06 



Na 2 O 6.05 



CaO 23.17 



MgO 2.63 



Fe 2 O 3 0.44 



P 2 O 5 27.98 



SO 3 1.26 



Cl 1345 



Accepting these figures as fairly accurate, and they agree 

 pretty well with the results of all analysts who have dealt with 

 the question, i liter of average cow's milk would contain the 

 following amounts of the several constituents : 



K 2 O 1.74 gm. 



Na 2 O 0.44 gm. 



CaO 1.67 gm. 



MgO 0.19 gm. 



Fe 2 O 3 0.03 gm. 



P 2 O B 2.02 gm. 



SO 3 0.09 gm. 



Cl 0.97 gm. 



7-15 



Noteworthy here are the relatively large amounts of the 

 phosphates of calcium and potassium. These salts represent 

 all the mineral matters needed in nourishing the body. As 



