524 Bulletin 281. 



until the sample reaches constant weight. The loss in weight represents 

 the amount of water driven ofif. The loss in weight, divided by the 

 weight of the sample taken, and the quotient multiplied by 100, gives 

 the percentage of water in the butter. The test should always be run 

 in duplicate, one sample serving as a check on the other. By using 

 the water-oven and chemical balances, duplicates should be run which 

 will check within less than .1 of 1% of one another. 



This is the ideal way to test for moisture because the highest tem- 

 perature reached is 212° F. (100° C), that of boiling water. At this 

 temperature, none of the other constituents of the butter are volatile 

 and the only constituent driven off is the water. 



The dishes employed to hold the water are usually made of glass 

 or platinum. They should be flat bottomed, with rounded corners, 

 so that the butter will distribute itself evenly in a thin layer over the 

 bottom and allow the sample to dry more quickly. 



The disadvantages of the Chemical method in creamery practice are the 

 cost of the apparatus, the skill required in its manipulation, and the 

 length of time required to dry the sample. The balances are so delicate 

 that they would not long stand the treatment they would ordinarily 

 receive in a creamery. The length of time required to drive off all 

 moisture from a sample of butter is five to six hours. Sometimes the 

 sample will reach constant weight sooner, but usually not. 



THE GRAY BUTTER MOISTURE-TEST 



This test was invented by C. E. Gray of the United States Depart- 

 ment of Agriculture. The apparatus consists of a flask into which 

 is fitted by means of a rubber stopper a long, slender, graduated tube. 

 Into this tube the moisture from the sample is condensed. The upper 

 end of the tube may be closed with a ground glass stopper or a ground 

 glass stop-cock. The base of the condenser is enlarged into a bulb 

 for the purpose of catching and holding the condensed water which 

 is driven from the sample. Inside this bulb is a siphon tube which is 

 the outlet from the flask, and which prevents the escape of the water 

 back into the flask after it is condensed. Just above the bulb is a second 

 rubber stopper, over which is fitted a glass cylinder. This cylinder 

 makes a water-jacket around the condenser. The equipment includes 

 a balance for weighing the sample, although any accurate balance may 

 be used. The directions for using the apparatus are as follows: 



Balance two pieces of paper, one on each scale pan. Put the ten 

 gram weight on one side, and butter enough to balance the weight 

 on the opposite side of the balances. Then put the sample, including 



