CONTAMINATION OF MILK 63 



From twelve to twenty -four hours later pass through the machine 

 a definite quantity of water which has been boiled for a few moments, 

 in order to sterilize it, and then cooled. Catch samples of the water in 

 sterile test tubes and examine quantitatively. 



Repeat the trial by passing milk through a separator for four 

 days, cleaning the separator after each day's use by flushing with 

 cold water, then with a hot solution of washing powder, then with 

 hot water, to remove the washing powder. At the end of the period 

 pass sterile water through and examine as before. 



Washing utensils. The student should study the influ- 

 ence which the manner of washing utensils has on their 

 germ content. 



Few farms are provided with facilities for production of 

 steam, so it is much more difficult to clean utensils properly 

 on the farm than in the factory. 



Cans or pails should be washed in the same manner as on 

 the farm, and the results obtained compared with those ob- 

 tained from the examination of a pail or can washed in a 

 similar way and then steamed. 



Exercise. Each student will wash the cans furnished him in the 

 following manner : Rinse with cold water, wash in a warm solu- 

 tion of washing powder, and rinse with scalding water. One of the 

 cans should be examined as described in the previous exercise. The 

 other should be steamed for thirty seconds over a steam jet and then 

 examined. 



Plan for the production of sanitary milk. Each student 

 will prepare and submit for examination a plan for the 

 establishment of a plant for the production of milk of high 

 grade, and for the management of the plant. This plan 

 should include everything which may have a direct or 

 indirect relation to the milk as human food. The con- 

 struction of the stable has an indirect relation to the con- 

 tamination of the milk, the health of the animal to the 

 hygienic requirements, etc. 



