42 Milk and Its Products, 



amounts of butter so made were of inferior com- 

 mercial quality, could not be mixed with the whole 

 mass of butter, and entailed a considerable loss 

 upon the creamery. 



The oil -test churn was an outgrowth of this 

 method, intended to remedy its defects, and was in 

 a great measure successful. In operating the oil -test 

 churn, the individual samples taken from each patron 

 were very much smaller, and were taken in small 

 glass tubes. These tubes were put in a frame and 

 agitated until the fat was di-awn together in a solid 

 mass ; the tubes were then immersed in water suf- 

 ficiently warmed to melt the fat, and when so 

 melted the fat would float upon the surface of the 

 liquid in the tube. The tubes were allowed to 

 become cool, were then a second time agitated to 

 churn any particles of fat that had escaped the 

 first churning, and the fat remelted ; it then ap- 

 peared in the form of a clear layer of liquid upon 

 the top of the contents of the tube, and could be 

 readily measured. The proportion of melted fat 

 so obtained was taken as a measure of the butter 

 value of the cream of which it was a sample. 

 This test was generally used in cream -gathering 

 factories, and was a very fair measure of the 

 butter value of the cream. There was always a 

 portion of the fat remaining unchurned, but in 

 cream it was a small percentage. In milk, how- 

 ever, it was a much larger proportion, and the 

 oil -test churn was never successfully used for de- 

 termining fat in milk. 



