120 



GRADING AND TESTING MILK AND CR.'iA.M 



While the difference in the test of the samples under the two 

 methods was usually not great, yet the dipper method of sampling 

 proved unreliable. 



Sampling-tube. At creameries where milk is received, the 

 sampling-tube, or milk-thief, gives the best results and satis- 

 faction. It is very difficult in practice to get a proportionate 

 sample with a dipper, from day to day. To illustrate: A patron 

 who delivers 200 pounds of milk testing 3 per cent fat one day 

 may on another day deliver 100 pounds of milk testing 5 per cent 

 fat. If a dipperful is taken from each for a composite sample, the 

 test of that composite sample will be 3 + 5-^2, or 4 per cent. 

 According to this test, these 300 pounds of milk delivered will 

 contain 12 pounds of butter-fat. In reality 6 pounds of fat were 

 delivered in the 200 pounds, and 5 pounds of fat in the 100 pounds, 

 making a total of 1 1 pounds of fat. Thus we see that the dipper 

 method is not reliable, and in this case the patron was paid for 

 i pound of butter-fat too much for the two days' delivery. If 

 the sample taken from the 200 pounds of milk had been twice as 

 great as that taken from the 100 pounds of milk, then the com- 

 posite test would have been perfect, no matter whether it had 

 been taken with a dipper or with a sampling- tube. If the same 

 weighing-can is used every day, it is possible to maintain an 



