154 MODERN METHODS OF TESTING MILK 



it is impossible to make the test promptly, add bi- 

 chromate of potash to preserve the sample, as directed 

 on p. 30. (5) In testing the milk of several cows at 

 the same time, label each sample- jar with the number 

 or name of the cow furnishing the milk. (6) If the 

 milk is to be tested also for solids by the lactometer, 

 take about a half-pint sample from each milking. 



More strictly accurate results are secured if each 

 milking is sampled by a tube, as stated on p. 27. 



Weighing milk. In testing a cow, the milk must 

 always be weighed on the testing day immediately af- 

 ter the milking is completed. As it is so easy to weigh 

 milk, it is desirable to weigh the milk at every milking, 

 or, at least, on two or three days each week. Accurate 

 spring scales of moderate cost are available. 



Keeping records. Records of each cow tested 

 should be carefully kept, the following facts being re- 

 corded: (i) Date, (2) name of cow, (3) pounds of 

 milk given, (4) per cent, of fat in milk, (5) lactometer 

 reading, if desired. 



Calculating results. The following data can be de- 

 rived by calculation from the facts recorded above: 

 (i) Pounds of fat produced on day of test, (2) pounds 

 of fat and milk produced each month, (3) pounds of 

 fat and milk produced for one period of lactation. 



The amount of fat on the day of the test is found 

 by multiplying the total number of pounds of milk 

 given by the per cent, of fat found and dividing by 

 loo. For example, if the day's yield of milk is 25 

 pounds and the per cent, of fat is 4, the day's milk 

 contains i pound of milk- fat. (See p. 193). 



The amount of milk and fat produced each month 



