18 



a-. 



An imperfect test is caused by one of three things: 

 (1) Foam on the fat column obscuring the upper menis- 

 cus; (2) a dark-colored fat column containing dark parti- 

 cles and with dark particles obscuring the lower meniscus; 

 (3) a light-colored fat column containing white, curdy 

 material obscuring the lower meniscus. 



The first is caused by using hard water. Any one or a 

 combination of the following may cause the second trou- 

 ble: (a) The acid was too strong; (b) too 

 much acid was used^(c) the acid was too 

 warm when added to the milk; (d) the 

 milk was too warm when the acid was 

 added; (e) the acid was dropped directly 

 into the milk ; (/) the mixing of the acid 

 and the milk was interrupted before the 

 solution was complete ; or (g) the acid and 

 milk were allowed to stand too long in 

 the test bottle before being mixed. The 

 third trouble is caused by one or more of 

 the following: (a) The acid was too weak; 

 (b) too little acid was used; (c) the acid 

 was too cold when added to the milk; 

 (d) the milk was too cold when the acid 

 was added; or (e) the mixing was not 

 continued long enough to dissolve all the 

 serum solids. 



Tested Babcock glassware. Babcock-test 

 bottles and pipettes should always be 

 tested and found correct before being used. 

 It is now possible to purchase test bottles 

 and pipettes which have been tested and 

 approved by the United States Bureau 

 of Standards. Many States also have officials empowered 

 to test and approve Babcock glassware. The best way is 

 to purchase it already tested by the Bureau of Standards, 

 or to have it made to conform to the requirements of that 

 bureau and then tested by a State official. 



TESTING CREAM FOR FAT. 



While in a general way cream is tested by the Babcock 

 test in much the same manner as milk, there are some 



FIG. 15. Show- 

 ing method of 

 reading , fat 

 column in 

 milk testing. 

 Read from a 

 to &, not a to 

 c, nor a to d. 



