Condensed Milk and Milk Powder 



33 



Clean milk 



Fig. 6. Cotton Filters 



Dirty milk 



by rail, cards similar to Figure 7 may be mailed to the patrons. 

 The evidence is so conclusive that even the most obstinate patron 

 can not help admitting his guilt and can usually be induced to "clean 

 up." 



Fig. 7 



Fermentation Tests. — These tests, are of great value in the 

 rapid determination of the kind of bacteria with which the milk 

 from individual patrons is contaminated. Glass tubes are filled 

 one half full of milk from each patron. These tubes are set in a 

 constant water bath at 100 degrees F. and the changes which milk 

 undergoes are noted after six, twelve and twenty-four hours. 



A solid curd with a clear whey indicates that lactic acid bac- 

 teria are the chief organisms and that the milk has been produced 

 under cleanly conditions. These organisms are killed when the milk 



