342 THE HANDBOOK FOR PRACTICAL FARMERS 



Adding the water. — Hot water is then added to the bottles 

 until the contents come nearly to the lower part of the neck. 

 The whirling is then repeated for two minutes. Hot water is 

 again added until the fat reaches a point below the highest 

 graduation mark on the neck. It must never reach the top mark, 

 or some of the fat may be lost. This time the water should be 

 dropped directly into the fat in order to clear the fat of the light, 

 flocculent material which may be entangled in it and which would 

 later interfere ^^^th the reading of the test. The whirling is 

 repeated for another minute. The temperature at which the 

 readings are taken is between one hundred and thirty degrees 

 and one hundred and forty degrees F., and this should be borne 

 in mind when the water is added, the object being to add the 

 water at such a temperature that the temperature of the fat at 

 the close of the last whirling will be between these two figures. 

 The water used should preferably be soft water or condensed 

 steam. 



Reading the percentage. — Provided the test has been success- 

 fully conducted, the fat will be in a clear, yellowish liquid 

 column sharply separated from the clear and nearly colorless 

 acid solution inunediately below it and with no foam on top. 

 The bottles should be kept warm either in the tester or in 

 warm water until read, and the readings should always be 

 made at between one hundred and thirty degrees and one hun- 

 dred and forty degrees F. The fat at this temperature, 

 if other conditions have been correct, ^dll have a well-defined 

 meniscus at both the top and the bottom. The readings are made 

 from the extreme bottom of the lower meniscus to the extreme 

 top of the upper meniscus. An ordinary pair of dividers is 

 useful in making this reading. The points are placed at the 

 upper and lower limits, then lowered until one point is at the 

 mark ; the other point will indicate on the scale at the correct" 

 percentage for the sample tested. 



