THE CHEMICAL CONSTITUENTS OF MILK 303 



Carbonates and sulphates probably do not exist in the 

 original milk, or only in minute quantities, but are formed by 

 oxidation of the compounds of carbon and sulphur during the 

 process of incineration. Aikman l says that " a portion of 

 the phosphoric acid is formed by oxidation of the phosphorus 

 present in the casein to the extent of o'8 per cent." It is 

 right, no doubt, to distinguish between the phosphoric anhy- 

 dride originally present in the milk as phosphates of potash, 

 calcium, etc., and the phosphorus which is present as a consti- 

 tutent of " organic " compounds such as casein, lecithin, etc. 

 The latter, however, is probably also fully oxidised in lecithin 

 (p. 45) it certainly is i.e. it is present as P 2 O 5 , and that 

 compound is not formed during the process of combustion. 

 Fleischmann deducts these amounts to get the composition 

 of what he calls the true ash (cf. p. 8), which he gives as 

 follows : 



Per cent. 



Potash 25-64 



Lime 24-58 



Phosphoric anhydride . . 21-24 (+2-4 in casein) 



Chlorine 16-34 



Soda 12*45 



Magnesia 3-09 



Ferric oxide 0-34 



103-68 

 Deduct oxygen equivalent 



to chlorine 3-68 



lOO'OO 



In fresh whole milk 100 parts of casein are united to about 

 1-55 parts of calcium oxide. Allowing for this, and adding 

 up all the acids and bases, there appears to be an excess of 

 the latter. It is evident, therefore, that in the original milk 

 there must have been other (organic) acids corresponding to 

 the surplus bases, and that these have been destroyed on 

 incineration. Indeed, Henkel has obtained positive evidence 

 1 " Milk, its Nature and Composition." 



