•48 



Milk Supply 



These cotton filters may be pasted on a sheet of paper similar 

 to a milk sheet, arranged so that the circles are placed opposite the 

 respective patron's name or number.' When shown to the patrons 

 who come to the factory, they furnish a most effective object lesson 

 to them. When the milk reaches the factory on route wagons or 

 by rail, cards similar to Figure 9 may be mailed to the patrons. 

 The evidence is so conclusive that even the most obstinate patron 

 cannot help admitting his guilt and can usually be induced to 

 "clean up." 



Fig. 9. , 



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 bacteria 

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

 cleanly conditions. These organisms are killed when the milk is 

 heated in the hot wells. Such milk therefore is safe, unless it con- 

 tains excessive acid, as shown by the acid test. 



A curd with gas holes, or that which is torn to pieces in the 

 tubes, shows the presence of gas-producing germs. These come 



