150 MODERN DAIRY PRACTICE. 



exceedingly fine, suspended condition. The difference 

 between the milk and the fluid passing the filter is so great 

 that the latter hardly can be called milk. Its most nutri- 

 tious constituent is gone. By this filtration the steriliza- 

 tion of the milk is therefore obtained at the expense of its 

 nutritive value. 



In the experiments which I have made in filtering milk 

 by means of Chamberland's filter the fat globules of the 

 milk have furthermore often caused difficulties, as they 

 will not easily go through the filter at a rather low 

 temperature, and usually clog its inner portion so that 

 the cleaning is very difficult. The same must, of course, 

 also be the case when other methods of filtration are 

 applied. The method of sterilizing the milk through 

 filtration must then, at least* in its present phase, be re- 

 jected.* 



Sterilization of Milk by Heating. Before entering on 

 this subject it may be proper to state briefly the chemical 

 changes which milk undergoes in heating. These changes 

 are not noticed until the heating rises to about 185 

 F. (85 C.), when a small separation of albumen may be 

 observed as a white precipitate. Small quantities of 

 casein also seem to separate at the same time. If the tem- 

 perature is increased above 185, the albumen will be pre- 

 cipitated more heavily, and the power of coagulation of 

 the casein will be decreased. A. Mayer states that this 

 power is decreased even at 167 F. (75 C.). If, however, 

 the temperature of the milk is slowly raised to 167 F., yes, 



* While the apparatus mentioned are of no practical value for 

 sterilization of milk, they serve in an excellent manner as water-fil- 

 ters, and are extensively used as such, especially in larger cities, or 

 where the drinking-water available is not above suspicion. W. 



