22 METHODS OF QUANTITATIVE ANALYSIS. 



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scale should be from 1.025 to 1.646, with the marks indi- 

 cating the second decimal points at least 20 to 25 m. m. 

 apart. 



In order to obtain the normal specific gravity reading 

 and thus satisfy the market inspector, skimmed milk is 

 not infrequently adulterated with water. 

 In certain cases one may detect this adul- 

 teration in the following manner: The 

 milk in question is placed in a narrow, tall 

 cylinder and shaken thoroughly and tested 

 with the areometer, and then allowed to 

 stand quietly for 24 hours for the cream to 

 rise. After carefully skimming off the 

 cream, the milk is tested again. For good 

 cow's milk (whole milk), the first reading 

 should be from 1.028 to 1.033 ^"^ ^^'^'^ sec- 

 ond from 1.035 to 1.0365. For this purpose 

 the cream is allowed to separate from the 

 milk in a vessel provided with a faucet at 

 the bottom, through which one may readily 

 draw ofif the cream-free milk into another 

 vessel and then test it with the areometer. 

 The exact composition, however, may be 

 determined only by a complete chemical 

 analysis. 



The "lactodensimeter" designed by 

 Quevenne is an areometer with a scale 

 Tig. 1. of 14 degrees to 42 degrees. The de- 

 Lactodenfimete? grecs of the scale indicate th€ specific 

 kltlnspectorT" gravity, e. g., 14 represents the specific 

 gravity 1.014. Hence when the 



temperature is 15 degrees C, the reading shows directly 

 the density of the sample. For temperatures other than 

 15 degrees C. the proper correction must be made (see 

 tables pages 23 and 24). 



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