THE BABCOCK TEST 53 



When only one or a few pipettes need testing, 

 water can be used, running from a burette into each 

 pipette 17.6 cc. of water, which should just fill the 

 pipette to the mark, if accurate. (See p. 278). 



Testing accuracy of acid measure. Ordinarily the 

 acid measure does not need testing, since a little varia- 

 tion does not affect the results. When desired, it can 

 be tested by running in water or milk from a 17.6 cc. 

 pipette, known to be accurate. 



KEEPING GLASSWARE CLEAN 



It is very important that the test-bottles and the 

 pipettes used in the Babcock test should be kept as 

 clean as possible from fat adhering to the inside sur- 

 face. Unless a special effort is made, the bottles 

 quickly become covered inside with a film of fat, 

 which may be sufficient to increase appreciably the 

 results obtained when the bottles are used in testing. 

 The bottles should be kept entirely free from any fat- 

 film and the wall should be clear 

 and bright. This can be accom- 

 plished without serious trouble. 



As soon as a test is completed 

 and the amount of fat read, the 

 test-bottle, while still warm, should 

 be emptied. This' may easily be 



. 



TEST-BOTTLES ware jar or crock, covered with 



a board (Fig. 22), in which are 



several holes large enough to admit easily the necks 



of test-bottles. The bottle is inverted, the neck run 



down through one of these holes, and at the same time 



