32 



MANUAL OF MILK PRODUCTS 



were treated with chloroform at the rate of 50 c.c. to 1000 c.c. 

 of milk and the fat removed by means of a centrifugal machine ; 

 the removal of fat is necessary, since it clogs the pores of the 

 filter. The fat-free milk was then filtered through Pasteur- 

 Chamberland filtering tubes. Analyses were made of the milk 

 and of the serum. We did not determine those constituents 

 present in milk in traces only, such as iron, sulfuric acid, and 

 so on. 



A study of the data contained in the table enables us to show 

 the general relation of the constituents of milk to the constitu- 

 ents of milk-serum. The following form of statement furnishes 

 a clear summary of the facts : 



1. Milk Constituents 

 in True Solution in 

 Milk-serum : 



2. Milk Constituents Partly in 

 Solution and PartlyJ in Sus- 

 pension or Colloidal Solu- 

 tion: 



3. Milk Constituents 

 Entirely in Sus- 

 pension or Colloi- 

 dal Solution : 



(a) Sugar 



(b) Citric acid 



(c) Potassium * 



(d) Sodium 



(e) Chlorine 



(a) Albumin 

 (6) Inorganic phos- 

 phates 



(c) Calcium 



(d) Magnesium 



(a) Fat 

 (6) Casein 



The behavior of milk albumin attracts special attention on 

 account of marked lack of regularity in the results obtained. 

 We commonly think of milk albumin as readily and completely 

 soluble in water, and the question is therefore raised as to why 

 a considerable portion of it does not pass through the Pasteur- 

 Chamberland filter. In view of all the facts available, the 

 most probable explanation that has so far suggested itself is 

 that in fresh milk a part of the albumin is held by the adsorb- 

 ing power of casein. This suggestion is supported by results 

 obtained in the following experiments : Serum was prepared 

 from chloroformed fresh milk treated in different ways. In 

 the first experiment, serum direct from the fresh milk was 



