238 



Exaaiple : If sample contains 8 per cent, of solids not fat 

 and 2.5 per cent, of fat, and if 3 per cent, fat and 9 per cent, 

 of solids not fat are the legal standards, then 



3 __ 9x2.5 ^ ]g^ per cent, by weight of fat removed. 



o 



Chemical Adulterants or Impurities. 



Drags are added to milk as preservatives ; some are added 

 to change the specific gravity of milk and occasionally color- 

 ing matter is added to make the milk appear richer. 



Commercial milk, cream or butter may contain one or more 

 of the following adulterants : Boracic acid, borax, salicylic 

 acid, sodium salicylate, carbonate of soda, bicarbonate of soda, 

 lim'e water, formalin. The majority of commercial preserva- 

 tives are made up of one or more of the toUowing drugs : 

 Bjrax, b3rdcic acid, sodium salycilate, salicyhc acid, and for- 

 malin. As a rule, any preservative or coloring matter that 

 is used in milk without giving due notice to the purchaser 

 must be considered as a fraudulent adulteration. The follow- 

 ing test may be made to determine the presence or absence 

 of chemical adulterants. 



* 'Borax and Boracic Acid: lOOc.c. of milk are made alkaline 

 with lime water dried, and the mixture gently burned to ash. 

 Tae residue is acidified with concentrated hydrochloric acid, 

 and the mixture washed in a small flask with 20c.c. of methyl 

 alcohol. The flask is connected with a condenser and about 

 lOc.c. of the methyl alcohol distilled into a small platinum 

 dish. The dish is placed in a dark closet or room and the 

 alcohol ignited, when, if a trace of boric acid or borax were 

 present, it burns with a grass-green flame. Blank tests must 

 be made with the re-agents used to prove absence of boric acid 

 in them."* 



" Place in a porcelain dish one drop of milk with two drops 

 of strong hydrochloric acid and two drops of turmeric tincture ; 

 dry this on water bath ; cool and add a drop of ammonia by 



* N. Y. Board of Health Report, 1896, p. 160. 



