The Babcock Test. 37 



too high if the temperature of the fat is allowed to rise 

 to that of the exhaust steam^during the process of whirl- 

 ing. In such cases the test bottles must be allowed to 

 cool to about 140, by placing them in water of this 

 temperature for a few minutes, before readings are 

 taken. 1 



A pair of dividers will be found convenient for meas- 

 uring the fat, and the liability of error in reading is 

 decreased by their use. The points of the dividers are 

 placed at the upper and lower limits of the fat column 

 (from a to 6 in fig. 10). The dividers are now lowered, 

 one point being placed at the zero mark of the scale, 

 and the mark at which the other point touches the scale 

 will show the per cent, of fat in the sample tested.. 

 The dividers must be tight in the joint to be of use for 

 this purpose. 



B. DISCUSSION OF THE DETAILS OF THE 

 BABCOCK TEST. 



43. The main points to be observed as to apparatus 

 and testing materials in order to obtain correct and 

 satisfactory results by this test will now be considered, 

 and such suggestions and help offered as have been 

 found needful from past experience with a great variety 

 of samples of milk, apparatus, and accessories. * 



1. GLASSWARE. 



44. Test bottles. The test bottles should have a ca- 

 pacity of about 50 cc., or less than two ounces; they 

 should be made of well-annealed glass that will stand 



1 See Wis. experiment station rep. XVII, p. 76. 



