44 



Testing Milk and Its Products. 



The black stains that sometimes stick to the inside of 

 test bottles after prolonged use, can be removed with a 

 little muriatic acid. 



PIG. 17. Back for holding test bottles in tank shown In Fig. 16. 



48. Pipette. The difference in the weights of various 

 samples of normal milk generally falls within compara- 

 tively narrow limits; if a given volume of water weighs 

 one pound, the same volume of the usual grades of nor- 

 mal milk will weigh from 1.029 to 1.033 pounds, or on 

 the average 1.03 Ibs. 18 grams of water measures 18 

 cc. 1 ; 18 grams of milk will therefore take up a smaller 

 volume than 18 cc., viz: 18 divided by 1.03, which is 

 very nearly 17.5. This is the quantity of milk taken 

 in the Babcock test. A certain amount of milk will ad- 

 here to the walls of the pipette when it is emptied, and 



i Cubic centimeters (abbreviated: cc.) are the standard used for meas- 

 uring volume in the metric system, similar to the quart or pint measure 

 in our ordinary system of measures. One quart is equal to a little less than 

 1,000 cubic centimeters. In the same way, grams represent weight, like 

 pounds and ounces. One cc. of water at 4 Centigrade weighs 1 gram; 1,000 

 grams (=1 kilogram) are equal to 2.2 Ibs. Avoirdupois. (See Appendix for 

 Comparisons of Metric and Customary Weights and Measures.) 



