DETECTION OF ADULTERATION 



By far the larger part of the laboratory work on 

 milk is for assistance in the sanitary control of the 

 supply, and the analyses are principally directed 

 to the detection of the ordinary forms of adultera- 

 tions. The most important of these are: skim- 

 ming, watering and use of coloring, thickening 

 and preserving agents. Skimming and watering 

 are detected by determining fat and total solids; 

 from these data the solids not fat are calculated. 

 For the ordinary purposes of milk control, fat 

 can be estimated with quite sufficient accuracy 

 by centrifugal methods. The total solids may be 

 estimated directly as described on page 12, or 

 calculated from the sp. gr. and fat as indicated on 

 page 21. 



Judgment whether a given sample has been 

 skimmed or watered depends in many cases upon 

 the standard for whole milk. Some irregularity 

 of standards for fat and solids not fat exists, and 

 the opinion of the analyst will be determined, 

 therefore, by the standard of the locality. In 

 most cases the standard for fat is between 3 and 

 4%, and that for total solids about 8.50%. 



As fat diminishes the sp. gr. of milk, and the 

 41 



