Butter Moisture-Tests. 527 



The cup is placed on the scales and balanced with the aid of the 

 weight. The sample weight is next placed in the scale pan opposite 

 the cup, and butter placed in the cup until the scales balance. The 

 sample is then heated, the cup being held over the flame by means of 

 the hot pan lifter. The butter will foam as it becomes heated, and 

 when the foaming begins to subside it is a sign that the moisture is 

 nearly all expelled from the sample. The mirror is now held over the 

 sample, and when moisture no longer collects on the mirror the water 

 has been driven off. During the process of heating, the sample should 

 be rotated in the cup from time to time. This is to break up the blanket 

 of casein which forms over the surface of the butter and prevents the 

 moisture from escaping. This covering of casein also prevents the 

 escape of heat, and the bottom of the sample is likely to char. When 

 the heat finally breaks through the •casein, some of the volatile parts 

 of the butter are carried off. After the moisture no longer condenses 

 on the mirror, the cup is allowed to cool to about room temperature 

 (6o°F. to 70° F.) and is then placed on the balances. It is lighter 

 of course than before heating, since the moisture which was in the sample 

 has been drawn off. The small weights which measure directly in 

 percentages are added to the scale pan with the cup until the scales 

 balance. By adding together the numbers on the weights, the percentage 

 of moisture driven off is obtained directly without other computations. 



The results obtained by use of this test were nearly always higher 

 than those obtained by the official method, although they are not so 

 high as to make a serious difference in the creamery work. The slightly 

 higher reading is probably due to the fact that exposing the sample 

 to the direct force of the flame drives off something beside moisture. 



The test is easy to operate and fairly durable, having no glass parts 

 except the mirror, and thereby not so likely to become broken. The 

 cup in which the sample is heated would be much better if it were 

 plainer and of heavier material. The top of the cup is bent over, and 

 when washed moisture collects under the rim. This is difficult to remove, 

 and therefore when weighed along with the cup makes a serious error 

 in the results. Some difficulty is also experienced in keeping the mirror 

 cool enough to condense the moisture. In operating the test, one has 

 to hold the mirror over the sample many times to make sure that the 

 butter is not being heated too long. This necessarily brings the mirror 

 constantly near the flame, and it soon becomes so warm that the moisture 

 passes off before one can observe it. It is best to heat the sample over 

 a low flame, and not allow the cup to become heated above the contents. 



