30 



INTRODUCTORY 



-THE CONSTITUENTS OF MILK. 



represents the figures obtained by Stohmann, Lebmann, and 

 Ritthausen ; it is probable that the last three observers did not 

 remove Storch's mucoid protein so completely as the others : — 



Hammarsten and Chittenden purified their casein by solution 

 in alkali and reprecipitation several times ; Ritthausen worked 

 on the copper salt ; and Lehmann used what he designated 

 " genuine " casein, which was separated from milk by the use of 

 a porous plate. 



Lehmann found that in "genuine" casein 1'45 to r75 parts 

 of lime were combined with 100 parts of casein ; one molecule 

 C'a(3 to one molecule C^jHossN^iSPOj., requires a proportion 

 1"5.3. Soldner has also shown that two lime compounds exist 

 containing r55 and 2'39 per cent. CaO respectively, which 

 correspond with CaO and 1 '5 CaO to one molecule of casein. 



N 



The author has found that —— sodium and potassium carbonate 



solutions treated with an excess of casein dissolve 1-86 and 1-83 

 parts per 100 c.c. respectively. The first formula would give 1-84. 

 It appears probable that casein exists in milk as a calcium 

 sodium salt combined with one molecular proportion of tri- 

 calcium phosphate. The author has found that by filtration 

 through a porous cell the compound separated has the com- 

 ijosition : — 



It was also found that on adding 8-6 c.c. of normal hydro- 

 chloric or sulphuric acid per litre the casein was precipitated 

 on boiling, and the acidity of the serum was equal to the acidity 

 of the milk after boiling. The quantity of acid required by the 



