BY H. G. CHAPMAN. 443 



is low, being 5° or less. Filtration through porcelain removes 

 not only the fat and caseinogen but also the greater part of the 

 phosphate which is present in suspension, not in solution. 



In 100 c.c. milk there has been found 0-236 gm. P 2 5 , while 

 in 100 c.c* of the filtrate through porcelain has been found 

 - 082 gm. P 2 5 . Since caseinogen contains phosphorus, a 

 determination of the phosphate not combined with caseinogen 

 has been made. 20 c.c. milk were heated to 70°C and mixed 

 with 20 c.c. 2 % "acetic acid, likewise heated to 70°C. After a 

 few minutes' standing the precipitate was filtered off. Of the 

 filtrate 32 c.c. were collected and considered to correspond to 

 Jf ths of the 20 c.c. milk. The phosphate was estimated by- 

 calcining with excess of pure soda, by precipitation with ammo- 

 nium molybdate and by weighing the phosphate in the latter 

 precipitate as magnesium pyrophosphate. The weight of P 2 5 

 uncombined with caseinogen in the milk has been found to be 

 0*175 gm. A little more than one-half of the uncombined phos- 

 phate was thus removed by filtration through porcelain. 



In the sample of milk under consideration the acidity was 12° 

 and the total phosphate equivalent to 0236 gm. P 2 5 % of which 

 0*175 gm. P 2 5 % was uncombined with caseinogen, while after 

 filtration the aciditv fell to 4° and the phosphate to 0*082 gm. 

 P,0 5 %. 



From these figures it is evident that the increased acidity of 

 the whole milk is due not only to the presence of phosphates but 

 also to the caseinogen which possesses similar powers of changes 

 from dicaseinate to monocaseinate and vice versd. 



In conclusion I beg to record my thanks to Professor Anderson 

 Stuart, in whose laboratory this investigation was carried out. 



* 100 c.c. filtrate corresponds more nearly to 112 c.c. milk than to 100 c.c. 

 milk. 



