42 



i 



Coloring matters : The use of colors for the coloring of butter 

 and cheese has become so common in dairies, that now we find 

 them occasionally used for the coloring of poor blue milk. They 

 may be detected in the following manner : 



500 c.c. of milk are coagulated with acid, or better, by the addi- 

 tion of 70 per cent, alcohol. 



The liquid is then filtered ofE and evaporated to 50 c.c. Addi- 

 tion of soda or ammonia produces a dark brown color in the pres- 

 ence of turmeric. 

 'Q Annato: A blue coloration on addition of concentrated sul- 

 phuric acid, would indicate the presence of annato. 



Preservatives : To prevent the souring of milk during the hot 

 season, various substances have been recommended. The appli- 

 cation of these by producers and dealers should not be tolerated, 

 but should be left to the consumer's choice. 



Producer and dealer should attend solely to cleanliness of treat- 

 ment and the cooling of the milk, which even during the summer 

 is sufficient to allow the safe transportation of the milk for con- 

 siderable distances. To prevent souring, the use of carbonate or 

 bi-carbonate of soda or potash is tolerated in France and England. 



To demonstrate their presence, 50 c.c. milk are coagulated with 

 70 per cent, alcohol. The fluid is filtered and evaporated to 

 dryness. The residue, on addition of hydrochloric acid, will 

 effervesce when these salts had been used. 



Neither normal whey nor milk ashes contain alkaline carbonates. 



For a qualitative and quantitative determination of the alkalies 

 in milk, at least 500 c.c. are required. In some cases, milk of lime 

 has been used as a means of preserving milk. The reaction of 

 such milk is alkaline. After coagulation with acetic acid, the 

 whey is evaporated to one-sixth of its volume, filtered, and tested 

 with sulphuric acid, which, in the case of lime having been used, 

 will produce a precipitate of gypsum. {Chalk has also been em- 

 ployisd. Of about 300 samples examined by Editor iov the Metro- 

 politan Board of Health, in New York, only one sample contained 

 chalk.) 



Salicylic acid and salicylate of soda have, of late, been 

 recolnmended and used for the preservation of milk. To deter- 

 mine its presence, 100 c.c. of inilk are coagulated by the addition 

 of 70 per cent, alcohol. The whey is filtered off, and evaporated to 



