48 MODERN METHODS OF TESTING MILK 



point. It is often the custom simply to test the scale 

 as a whole, running in 2 cc. of water at once, in which 

 case the upper surface of the liquid should be on a 

 level with the 10 per cent, mark, if the graduation is 

 correct; for proper accuracy, the water should not 

 reach below or above the mark more than o.i cc. It is 

 possible that the results may show the scale to be ac- 

 curate at the 10 per cent, mark and yet be incorrect 

 at some point below. It is, therefore, desirable to 

 apply the test to several different points between the 

 zero and 10 per cent, marks. 



In the case of cream- testing bottles, the same oper- 

 ation is performed, but it must be kept in mind that 

 the relation of the volume to per cent, marks is differ- 

 ent in i8-grarn bottles as compared with g-gram bot- 

 tles; each cubic centimeter in the graduated neck of 

 an 1 8-gram bottle stands for one-half the percentage 

 that it does in a Q-gram bottle; or, stated in another 

 way, each per cent, in an 1 8-gram bottle represents 

 twice the volume or number of cubic centimeters that 

 it does in a g-gram bottle. This is shown clearly in 

 the following table: 



In 18-gram bottles In 9-gram bottles 



0.05 cc. equals 0.25 per cent. 0.50 per cent. 



o.i " " 0.50 " " 1.00 " " 



0.2 " " 1.00 " " 2.00 " " 



0.4 " " 2.00 " " 4.00 " " 



0.5 " " 2.50 " " 5.00 " " 



07 " " 3.50 " " 7.00 " " 



1.0 " " 5.00 " " 10.00 " " 



2.0 " " 10.00 " " 20.00 " " 



3.0 " " 15.00 " ." 30.00 " " 



5.0 " " ......25.00 " " 50.00 " " 



