29 



can find customers who are willing to pay extra price if the quality 

 is assured, he can warrant that the customer will receive what he 

 pays for. With the Babcock tester the farmer can know what he 

 is selling. If he ships to the Boston contractors, he can, by the 

 use of the Babcock tester, remove much of the mystery which has 

 hitherto enveloped the statute standard. He can keep supervision 

 over the quality of his milk sales and can know whether he is send- 

 ing standard milk or not. If he receives complaint from the con- 

 tractors, he has proof from his own tests of the kind of milk that 

 has left his farm. 



In order to understand the use of the Babcock tester in the sale 

 milk business, a few fundamental principles about milk must be 

 understood. The milk of individual cows varies from day to day. 

 If the milk of a cow were to be analyzed every day, and the results 

 of those analyses represented pictorially by a line which should 

 go up as the quality of the milk increased, and vice versa., the 

 line would, speaking in a general way, be something like a row 



ofv's: My\j\j\j\jy. 



This is a somewhat exaggerated statement, because the irregu- 

 larities will not be as uniform as is indicated by the above, and 

 because, as the period of lactation increases, the amount of solids 

 in the milk will increase ; but in a general way the above is a repre- 

 sentation of the quality of milk from day to day of individual cows 

 under normal conditions. Ordinarily this variation is inside of one 

 per cent, and when a variation occurs in one direction one day, the 

 pendulum usually swings the other way, and about as far, the next 

 day. When the milli of several cows is considered we find that 

 these variations in the different animals do not coincide, but where 

 the milk of one shows an increase, this increase may be offset by 

 the decrease in the quality of milk of another. Hence the mixed 

 milk of a herd is more constant in quality than the milk of single 

 animals, and does not vary much from day to day. Where the 

 conditions of barn and feed are such that the cows can have an 

 adequate amount of food under comparatively uniform conditions, 

 when they are neither too cold in winter, nor obliged to tramp long 

 distances in a dry pasture under a burning sun, annoyed by flies, 

 for summer rations, the quality of the mixed milk of a herd is quite 

 uniform the year around. 



Variations in the quality of milk are largely due to variations in 

 the amount of fat. The amount of the other solids is compara- 

 tively constant. While we frequently find a variation of 3 per 

 cent or over in the fat, the variation of the other solids is usually 

 less than 1 percent. Ordinarily the amounts of solids not fat and 

 fat increase together, though not in the same ratio ; and speaking 



