Absorption of Odours by Milk. 497 



might not act in the same way as that which had been 

 heated up after once being cooled. To meet this possible 

 objection another set of experiments was instituted. 



In the second series the milk was drawn from the animal 

 and immediately submitted to the influence of different odours 

 emanating from certain kinds of volatile essential oils, as it 

 was thought that they would permit of a ready detection and 

 would better serve to illustrate the truth of the principle 

 involved. For this purpose trials were made with oil of 

 cinnamon, winter- green, and peppermint, as well as with 

 horse manure and urine of cows. The results of this second 

 series of tests also showed that the odour in the warm milk 

 is more intense than in the cold, signifying that absorption 

 takes place in a greater degree when the milk is warmer 

 than the surrounding air. In 148 cases out of 171, or 86 per 

 cent,, the observers decided independently that the odour 

 peculiar to the different tests was more apparent in the warm 

 than in the cold milk. 



Regarding the relative intensity of the odours absorbed, 

 the essential oils seemed to be taken up more actively by the 

 milk than the other substances. Peppermint was the most 

 readily absorbed ; after exposures lasting ten, fifteen, and 

 twenty minutes, a slight though distinct trace of this odour 

 could be detected in the warm milk. The odour arising 

 from fresh horse manure did not seem to be absorbed in so 

 marked a degree as that given off by the oils. 



The odour of fresh urine readily tainted the milk, but stale 

 urine did not seem to impart so marked an odour. As the 

 volatile ammonia which is generally evolved from decom- 

 posing urine is not absorbed so readily in warm as in cold 

 liquids, it was thought that this property might change the 

 general results ; but there is, it appears, a peculiar odour 

 arising from urine, independent of the ammonia contained, 

 which imparts to milk an undesirable taint that is readily 

 recognised. 



In the light of the above data, Dr. Russell states that the 

 common ideas of dairymen that milk gives off odours when 

 warm, and takes them up only when cooler than the 

 surrounding air, stand in need of modification. Undoubtedly, 



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