726 EXPERIMENT STATION RECORD. 



the following day, and agaiu wliirled, aud this operation was repeated 

 for the third time. 



Partial analyses were made of the railk and the several products 

 obtained in the experiment, the results of whicli are given. The 

 deposit upon the bowl was very much larger the first day than upon 

 subsequent days, but the proportion of ash in the deposit increased in 

 the second and third whirlings. From this the author believes it is 

 evident that the ash is not chemically combined with the casein, for in 

 that case the proportion of ash would have been the same in all cases. 

 It is also evident that the casein is more easily separated from the milk 

 than the insoluble phosphates of the ash. 



"The analyses made in tbese trials indicate that the deposit upon the bowl con- 

 sists essentially of casein and insoluble phosphates, its other constituents being 

 easily accounted for by the soluble matter held mechanically in it. The sugar, albu- 

 men, and a large portion of the ash are evidently in solution, as their amount in the 

 milk is not diminished by whirling." 



To study the question whether the solubility of the nitrogenous con- 

 stituents of milk is changed by heat in ])asteuriziug, a quantity of skim 

 milk was divided, one portion being pasteurized and then whirled for 4 

 hours, and the other being whirled immediately. Analyses showed that 

 the solids-not-fat and the nitrogen were practically the same, in the milk 

 before and after whirling, indicating that '' neither the casein nor the 

 albumen have been changed in solubility by pasteurizing." 



"The fact that pasteurized milk is not as readily coagulated by rennet is satisfac- 

 torily explained by assuming that a portion of the lime salts have been removed 

 from solution by heat. This explanation is plausible, for the addition of a little cal- 

 cium chlorid, acid phosphate or other soluble salt of lime restores pasteurized milk 

 to its normal condition so far as its l>ehavior with rennet is concerned. It is also 

 restored by passing carbonic-acid gas into the milk or by the addition of any dilute 

 acid which dissolves phosphate of lime. For these reasons the writer is of the opin- 

 ion that the insoluble lime salts of milk are to some extent increased by heat and 

 that the larger amount of ash found in the residue from pasteurized milk in the last 

 experiment is due to this rather than to development of lactic acid in the fresh milk." 



The relation bet-ween milk solids and the yield of cheese, S. M. 



Babcock ( Wisconsin Sta. Bpt. 1895, pp. 100-119). — The insoluble con- 

 stituents of milk, i. e., fat, casein, and insoluble phosphates of lime and 

 magnesia, the author terms the cheese-producing solids. Since the 

 "proximate separation of these solids from milk by the coagulation of 

 casein may be regarded as the essential feature in the manufacture of 

 cheese," the cheese-producing cai)acity of a milk may be measured by 

 the amount of insoluble matter which the milk contains. The deter- 

 mination of these insoluble solids is believed to furnish an accurate and 

 convenient basis for calculating the relative yield of cheese from milk 

 supplied by different patrons of a cheese factory. To facilitate this, the 

 author presents formulas which he has worked out. Tlie necessary data 

 areobtained by determining the percentage of total solids in milk and in 

 the whey obtained from it in a definite manner. Omitting the details 



