THE PASTEURIZATION OF MILK 



necessary requirement in order to equalize tem- 

 peratures. 



The ultra-violet rays have been suggested as a 

 means of killing bacteria in milk. Since, however, 

 these rays have but little penetrating power, it has 

 been found that the opaque character of milk pre- 

 vents obtaining the good results which have re- 

 sulted in the use of the ultra-violet rays in water 

 purification. 



The ozone process, which will by oxidation de- 

 stroy some forms of bacterial life, and which will 

 destroy odors, also acts upon the constituent parts 

 of milk and so changes them that it seems probable 

 that ozone can never be satisfactorily substituted 

 for the usual pasteurization process. 



An ingenious idea has been brought to the 

 writer's attention by which it was proposed to de- 

 stroy the bacteria by treatment in vacuum. It is 

 well known that when persons work under abnor- 

 mally high air pressure as in tunnel construction 

 under rivers, etc., it is necessary for them to exer- 

 cise the greatest care in coming out into the normal 

 air pressure. The air, which under pressure is 

 absorbed in the bodily tissues, suddenly expands 

 when the abnormal pressure is relieved. The cells 



92 



