314 MILK AND CREAM TESTING 



butter maker and occasionally encourages him to record a test 

 lower than the actual reading, to recover in the operation. 



If a cow is being tested and she yields 30 pounds of milk 

 for thirty days, she has produced 900 pounds of milk. If this 

 is sho'^vn to test 3.9 per cent fat, she will then be given credit 

 with having produced 35.1 pounds of fat, whereas a glass- 

 stoppered bottle which would prevent evaporation of water might 

 show her true test to have been 3.6 per cent fat. This would 

 credit her with having produced only 32.3 pounds of butter fat, 

 or a difference of 2.8 pounds of fat. If the fat is figured as 

 worth 30 cents per pound the cow has been given credit with hav- 



FiG. 107. — Composite milk sample bottles. Evaporation of moisture must be prevented. 

 The bottle at the right is preferable to the fruit jar, 



ing produced 84 cents' worth of product in one month more than 

 she is entitled to. At this rate each cow in the herd would have 

 been given credit during the year with having produced from 

 $5 to $10 worth of product more than was rightly her due. The 

 money value difference between a true test and one made too 

 high by the evaporation of water from the sample is better shown 

 in the case of the whole milk creameries. If a farmer have 

 twelve cows averaging 25 pounds of milk each, or 300 pounds 

 of milk per day, they will in fifteen days produce 4500 pounds 

 of milk. With the fat percentage in error as above mentioned, 

 the farmer will be given credit for having delivered 13.5 pounds 

 of fat in the 15 days, more than he had actually delivered. If 



