DEVELOPMENT OF CITY MILK SUPPLY PROBLEMS 37 



carbon and passing it through a 100-mesh to the inch sieve. 

 The desired amount of this carbon is then weighed in a ground 

 glass slide and transferred to a small beaker containing 50 

 c. c. of milk. After stirring until uniformly distributed, the 

 contents of the beaker, while rotating, are poured quickly into 

 the sediment tester. The carbon is deposited upon the cotton 

 disk in the tester and this disk may be used as a standard 

 for comparison with disks resulting from the testing of milk 

 samples. 24 



Standards prepared in this way are quite uniform and in 

 the lower dilutions clearly show differences of 0.25 milligram. 

 A series of these standards may be conveniently mounted on 

 a card and protected from dirt by a strip of glass or celluloid. 

 With such a series of standards at hand, the making of a sedi- 

 ment test from a sample of milk and the estimation of the 

 amount of dirt present by comparison with these standards 

 occupies but two or three minutes. 



THE PROBLEM OF KEEPING QUALITY 



The first article prepared by Dr. Russell for his first annual 

 report was entitled The Source of Bacterial Infection and the 

 Relation of the Same to the Keeping Qualities of Milk. 2 * At 

 that time the idea was almost universal that the overshadow- 

 ing importance of bacteria in milk lay in their relation to 

 the health of the consumer. A portion of this fear of germ 

 life arose from the feeling that since certain germs cause 

 definite diseases, all germs must be dangerous. The faulty 

 logic in this reasoning is too evident to need discussion. The 

 nightshade is truly a poisonous plant while its near relative, 

 the potato, is one of our most important sources of food. 



The fact that the death rate of babies is highest during the 

 hot months when the germ content of the milk supply is also 

 highest early led to the belief that the high germ content 



34 The details of the preparation of these standards were worked out by 

 James D. Brew under the general direction of the author. 



25 H. L. Russell, The Source of Bacterial Infection and the Relation of 

 the Same to the Keeping Qualities of Milk in Annual Report, Wis. Agr. 

 Exp. Sta., 11 (1894), pp. 150-165, 1S95. 



