68 MILK HYGIENE 



maldehyde for testing it is important to know that, 

 according to the researches of Smith and Leonard, only 

 a small part of the formaldehyde is distilled over; if 

 the milk is rendered alkaline even less is collected, but 

 if the milk is acidulated a larger proportion goes into 

 the distillate. B. H. Smith (as reported by Leffmann) 

 has shown that if 100 c.c. of the milk sample be mixed 

 with 1 c.c. of dilute sulphuric acid, of a strength of one 

 of acid to three of water, and distilled, one-third of the 

 formaldehyde present will come over in the first 20 c.c. 

 of the distillate. L.P.] 



/. Alkalies. In connection with antiseptics, the ad- 

 dition of alkalies should be mentioned. To be sure, 

 these do not have an antiseptic effect, but still, by the 

 neutralization of the acid formed, they hide changes and 

 conceal the fact that the milk is, perhaps, already 

 spoiled. In this connection the substances to be consid- 

 ered are carbonate and bicarbonate of soda, also chalk 

 and potash. A distinct alkaline reaction of milk to lit- 

 mus paper points to such an addition of alkali and 

 demands a further test with rosolic acid. 



Ten c.c. of milk are mixed with 10 c.c. alcohol (96 per 

 cent.) and a few drops of a 1 per cent, solution of rosolic 

 acid are added. Pure milk will become brownish yel- 

 low, while milk treated with alkalies takes on a rose red 

 color. (Hilger, C. Schmidt.) 



III. ABSORPTION OF ODORS 



Milk possesses a peculiar power to absorb odors. It 

 was mentioned above that goat 's milk which is drawn in 

 the stable in which the bucks are stalled absorbs some- 

 thing of the same clinging, unpleasant, characteristic 

 odor. Likewise, cow's milk assumes a foreign odor and 

 a false taste when it stands in a place where there are 

 strongly smelling substances and especially when it is 



