CREAMERY BUTTHR MAKING 39 



III. DETECTION OF MILK ADULTERATION WATERING AND 

 SKIMMING. 



A knowledge of the methods of detecting watering and 

 skimming of milk is in many cases of considerable value 

 to butter makers, even when the milk is bought on the fat 

 basis. Where the milk is bought irrespective of its fat 

 content, such a knowledge is simply indispensable for the 

 welfare of the creamery. 



In normal milk ranging in fat from 3% to 5%, it is 

 not difficult to detect a moderate amount of watering and 

 skimming. We speak of normal milk because this means 

 the milk from a full milking and excludes colostrum milk, 

 milk from diseased cows and those far advanced in lacta- 

 tion. Normal milk cannot be expected when cows are 

 either only partially milked, diseased, or very far ad- 

 vanced in lactation. 



The accuracy of determining the amount of watering 

 and skimming becomes greater in proportion as the sam- 

 ple represents more cows. " For example, no sample of 

 rnilk from a herd consisting of six or more cows has been 

 known to average below 3% fat. For this reason any 

 sample of milk testing below 3%, when taken from a 

 herd, is to be looked upon with suspicion. On the other 

 hand there are records of individual cows that show tests 

 as low as 1.7% and as high as 8%. It is owing to these 

 extreme variations in the composition of milk from indi- 

 vidual cows, that small amounts of adulteration cannot 

 be estimated with the same degree of accuracy in such 

 milk as in herd milk. 



Detection of Adulteration. The general procedure in 

 determining whether milk has been watered or skimmed, 

 or both, is as follows : 



