New York Agricultural Experiment Station. 309 



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 adsorbing 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 com- 

 pared with serum obtained from whey which had been obtained from 

 another portion of the same milk by treatment with rennet-extract. 

 In the second experiment, serum direct from fresh milk was compared 

 with (a) serum obtained from another portion of the same milk 

 after souring, and (b) serum obtained from another portion of the 

 same milk to which some formaldehyde solution had been added. 

 Albumin was determined in each case by boiling after addition of 

 acetic acid, following the details given in the provisional method of 

 the Association of Official Agricultural Chemists. The results of 

 the experiments are given below. 



First Experiment. 



Fresh milk 



Serum from fresh milk 



Serum from whey 



Second Experiment. 



Fresh milk 



Serum from fresh milk 



Serum from sour milk 



Serum from milk plus formalde- 

 hyde . 



0.245 



92.21 



In the first experiment it is seen that when casein is precipitated 

 by rennet solution the curd (the precipitated casein or para- 

 casein) carries down part of the albumin with it; the amount 

 thus carried down is approximately equal in this case to that 

 retained along with the casein on the external surface of the 

 Pasteur-Chamberland filtering tube, when whole milk is filtered 

 through such a filter. 



In the second experiment we see that when the casein is precipitated 

 with acid, as in the case of natural souring, the adsorbing action of 



