32 QUESTIONS AND ANSWERS 



until the operator can distinguish the dark lines on 

 the cylinder through the liquid. The graduations 

 at the surface of the liquid in the barrel then in- 

 dicate the percentage of fat in the milk. 



What is a pioscope? 



It is an instrument for determining roughly the 

 quantity of fat in milk or whether the milk is of a 

 high or low grade. It consists of a shallow recep- 

 tacle with a rim raised slightly above a surround- 

 ing hard, black disk. Into the receptacle a few 

 drops of milk are placed and covered with a cir- 

 cular cover-glass having variously tinted seg- 

 ments. The milk spreads out in a thin layer and 

 its color as seen against the dark background may 

 be matched by one of the tinted glass segments. 

 The different tinted segments represent different 

 grades of milk. 



Describe in brief the Babcock test. 



The test was perfected by Professor Babcock and 

 given to the public in 1890. It depends upon sul- 

 phuric acid to free the fat-globules and upon cen- 

 trifugal force to bring the fat together so that it 

 may be measured. A definite quantity of the milk 

 is placed in a glass bottle, sulphuric acid is added, 

 the mixture well shaken, then placed in a centrif- 

 ugal machine and whirled to bring the fat to- 

 gether. Water is then added to the bottles ur.til 

 the fat rises in the graduated part of the neck, 

 where the volume of the melted fat can be read 

 directly in percentage. 



