Contamination of Milk. 41 



while in cans carefully washed and then steamed for 5 

 minutes, it was reduced to 880 per cubic centimeter. It 

 would not be worth while to institute measures that 

 would accomplish the destruction of this small residual 

 content. 



The use of steam, therefore, is of great service in elim- 

 inating bacterial life in all utensils. In apparatus of at 

 all complicated design, it is absolutely necessary. Of 

 course, ordinarily, steam can be applied only at the fac- 

 tory, as the farm does not usually afford facilities for its 

 easy generation. This fact has led in some cases to the 

 adoption of the method of cleaning and sterilizing the 

 cans at the factory rather than to await their arrival at 

 the farm. This custom is most frequently followed in 

 milk supply plants. 



It is also very important in cleaning dairy utensils to 

 see that they are rapidly and thoroughly dried after be- 

 ing washed and steamed. As pointed out above, the short 

 period of steaming that can be followed in practice does 

 not kill all the bacteria. If moisture is retained, condi- 

 tions permit of the growth of the undestroyed organisms. 

 Tests made on glass milk bottles showed that consider- 

 able growth occurred in the condensation water even 

 after quite thorough sterilization. Some of the devices 

 used for the sterilization of such utensils as milk cans 

 are so arranged that, after steam has been introduced, 

 hot air is passed into the can until it is thoroughly dried. 

 Other utensils such as cloth strainers become sources 

 of contamination unless the articles are thoroughly and 

 quickly dried after cleaning. 



In a general way, it may be said that whenever a uten- 

 sil is so constructed and in such a condition that every 

 portion of its surface can be reached by a cloth or a 



