THE TESTING OF MILK AND CREAM 



107 



cent points, so that with two testers, one can, if desired, test 

 the accuracy of the scale at the 4, 5, 8, and 10 points. There 

 are also testers of the same form made for cream bottles. 



"In using this bottle-tester, the following precautions are to 

 be observed : 



" (1) Have the upper surface of the liquid exactly on a level 

 with the zero mark in the neck of the test bottle before putting 

 the tester in. ^ 



" (2) Clean the inside walls of the neck of the 

 bottle from adhering liquid before testing. 



"(3) No air-bubbles should be allowed to ad- 

 here to the tester when it is below the liquid. 



" (4) The tester should be dry each time before 

 using." 



A special burette has been devised at the Uni- 

 versity of Wisconsin 1 by which the amount of 

 error can be read directly from the neck of the 

 test bottle, in percentage rather than in cubic 

 centimeters. 



"This burette (Fig. 6) has two sets of gradua- 

 tions, one designed for bottles for 18-gram and 

 the other for 9-gram samples, as in the case of 

 the 50 per cent 9-gram cream bottle. The bore 

 of the burette is so small that the space from 

 to 10 (on the 18-gram scale) is approximately 

 7|- inches. It has a capacity to deliver 2 c.c. 

 The length of the graduations on the neck of an 

 ordinary 18-gram test bottle, reading to 10, 

 is approximately 2-J inches. The graduations 

 on the burette occupy a length of approximately 

 18 inches from to 25 on the 18-gram scale. 

 It will deliver 5 c.c. The graduation on the 9-gram scale is 

 necessarily twice as large as on the 18-gram scale. As the 



1 Wisconsin Bui. 241. 



FIG. 6. A 

 burette which 

 shows error in 

 percent age 

 rather than in 

 c.c. 



