Babcock Test for other Milk Products. 91 



The value of the divisions of the scale on the double- 

 necked test bottles has been a subject of considerable 

 discussion, and various opinions have been expressed 

 whether they show one-tenth or one-twentieth (.05) of 

 one per cent, of fat. By calibration with mercury the 

 value of the divisions will be found to be .05, or one- 

 twentieth, of one per cent., but as shown above, the re- 

 sults obtained in using the bottles for separator skim 

 milk generally come at least .05 per cent, too low, so 

 that, practically speaking, each division may be taken 

 to show one-tenth of one per cent., if the fat fills only 

 one division of the scale or less. 1 



The double-necked bottle is very convenient for the 

 testing of separator skim milk, thin butter milk and 

 whey. The milk, acid and water are added to the bottle 

 through the large side-tube ; the mixing of milk and acid 

 must be done with great care, so that none of the con- 

 tents is forced into the fine measuring tube and lost; it 

 is best to add half of the acid first and mix it with the 

 milk, and then add the rest. When the fat is in the 

 lower end of the measuring tube, it can be forced into 

 the scale by pressing with the finger on the top of the 

 side tube. 



In placing the double-necked bottles in the tester they 

 should be put with the filling tube toward the center so 

 as to avoid any of the fat being caught between this 

 tube and the side of the bottle when it resumes a verti- 

 cal position. 



This test bottle is more fragile and expensive than 

 the ordinary Babcock bottles, and must be carefully 



1 Wis. exp. station, bull. 52; Penna. exp. station," report 1896, p. 221. 



