10 



Milk containing blood will, on boiling, change its color from red 

 to brown, since hsemoglobine is decomposed on the application of 

 heat. Rennet and madder will color milk uniformly, and the color 

 thus produced does not undergo change on boiling. 



Yellow: The yellow color may be produced by certain vegetable 

 pigments. It is said to also accompany certain changes which are 

 characterized by the formation of stringy, skinny and lumpy 

 coagula, which sink to the bottom on standing. The supernatant 

 milk appears opalescent and stringy . This color is also observed 

 in jaundice. Cause : congestion and inflammation of the udder. 



Blue : A blue color in milk has rarely been observed at the 

 time of milking, unless it be produced by blue vegetable pigments. 

 The milk is in this case uniformly colored. Milk may, however, 

 after some time turn blue under the influence of certain ferments. 

 On the surface of the milk or the cream, beautiful indigo-blue 

 spots appear which gradually enlarge. After some time the color 

 ceases to increase, and then, even with the naked eye, the growth 

 of fungi can be observed. Already long before this the micro- 

 scope shows the presence of mycelium, vibrios and bacteria in such 

 milk. The original cause of this milk infection has been traced to 

 the growth of a certain fungus described by Fuerstenberg (see cut), 

 whereby the constituents of the milk are decomposed, giving rise, 

 as some believe, to the formation of aniline blue (tripheyyl- 

 rosaniline). 



