23 



until there is evidence of a clear separation of the fat ; then place the 

 samples in hot water, at a temperature of from 160 to 170 deg-rees, for 

 from fifteen to twenty minutes. 



If the separation be complete, the fat will be clear and yellow, and 

 there will be three distinct colunms with snaro lijies of division between 

 them, viz., a column of clear fat on io]), one of whey next, and one of 

 curdy matter at the bottom. If there be not a clear separation, cool to 

 about 90 degrees, churn again and proceed as before. 



To Take a Reading. There is a chart prepared for the purpose. 

 Placing the bottom in an upright position on the "base line" of the 

 chart, move it along until, when looking by the right siae of the bottle, 

 the top of the column of fat comes even with the uppermost slanting 

 line on the chart. Next, still looking by the right side of the bottle, 

 obsenve the line to which the bottom of the fat comes ; the number on 

 this line gives the reading. 



A small rule made specially for the purpose is more convenient 

 than a chart. Thiis, however, will give a correct reading only when the 

 test-tubes have been filled precisely to the mark. The chart consists 

 of a sliding scale, and gives the proportion of oil regardless of the 

 depth of cream taken or the diameter of the test-tubes 



Sometimes the fat, though clear, is somewhat open. In such cases, 

 or when the fat is not clear, allow the samples to become cold, and 

 then place in water at a temperature of about 120 degrees F., before 

 taking a reading. About 120 degrees is a very suitable temperature 

 at which to take readings. 



Meaning or the Reading. Cream that gives a reading of 100 in 

 the oil test will make one pound of butter for every inch of such cream 

 in a cream pail 12 inches in diameter; cream testing 120 will make 

 1.20 pounds of butter per inch. To find the pounds of butter, multiply 

 thj- number of inches by the reading and divide by 100- 



Theory of the Test. A standard or creamery inch is one inch 

 of cream (in a twelve inch pail) testing 100. 



One inch, therefore, contains 113 cubic inches. One pound of but- 

 ter contains about 25 cubic inches of butter oil, which is 22 per cent, 

 of 113. Therefore, any cream which will yield 22 per cent, of its 

 volume in butter oil, will yield one pound of butter per inch. Tubes 

 filled to the depth of 5 inches with cream which gives 1.1 inches of but- 

 ter oil, will vield one pound per inch, as 1.1 is 22 per cent, of 5. 



a' reading of 100 by the oil test would, therefore, theoretically, be 

 equal to 22 per cent, of fat. 



The relation between the oil test and percentage of fat or Bab- 

 cock test, may be viewed from the Babcock side as follows : The over- 

 run in Collecting Creameries may vary from 12 to 13 per cent to as 

 high as about 18 per cent. Then 100 pounds fat would probably yield 

 about 115 pounds butter. ^^^ 



1 pound of butter would thus be obtained from j^^- pounds fat. 



I inch of cream weighs 4-1 pounds. 



