MILK ADULTERATION 57 



in connection with samples suspected of being adulterated. 

 The index of refraction is reduced by the addition of water but 

 is unaltered by fat abstraction. The following are the mini- 

 mum figures for genuine milks when prepared by the usual 

 methods. 



TABLE XXXIII 

 REFRACTOMETER VALUES FOR MILK SERUM 



Although the above methods are capable of detecting the 

 abstraction of small quantities of fat, their possibilities regarding 

 the indication of added water are more limited, and it is doubtful 

 if they could be relied upon to detect additions smaller than 

 would be necessary to reduce the total solids or solids-not-fat 

 below the requirements of any reasonably high standard. 

 Even though these methods are reliable for the detection of the 

 abstraction of small amounts of fat, the advisability of using 

 them as a basis for the certification of adulteration, when the 

 fat exceeds the standard, is extremely doubtful owing to the 

 difficulty of securing a conviction. Those whose duties embrace 

 the analysis of public milk supplies meet many of these examples 

 and have, unfortunately, no option but to report them as gen- 

 uine, although they are undoubtedly sophisticated. This is 

 one of the inherent disadvantages of minimum standards. 



The addition of cane sugar or dextrin to watered milk for 

 the purpose of increasing the non-fatty solids is indicated by a 



low proteid value, an abnormally high - 4-r ratio, and a 



deficiency of ash. Methods for the detection and estimation 

 of cane sugar are given on page 88. Glycerine and starch 



