THE OILS IN MILK. 19 



it stimulates every change from curding and curing to putre- 

 factive decomposition. In butter, it leads on all the changes 

 that occasion rancidity and the final destruction of the 

 butter. Taken in connection with the ferment or yeast 

 whose action evokes it, the dairyman finds in it his bitterest 

 and deadliest foe. But like Hercules, it has a vulnerable 

 point. A little heat dissipates the oil and kills the yeast that 

 forms it. In fact, it will escape and get out of the way at all 

 ordinary temperatures, if it has a chance to do so. But heat 

 drives it away effectually, and is a perfect antidote to taint in 

 all its phases. A second antidote is filtering through some 

 good absorbent, like charcoal. Passing milk through char- 

 coal will remove taint from warm milk, and give it a most 

 delicious flavor. Cold will silence the activity of the yeast, 

 but will not kill it, and acidity will neutralize the oil for a 

 time, but it will assert its sway upon the first favorable 

 opportunity. In the treatment of milk, airing is a more 

 efficient antidote. 



There is another kind of oleaginous matter in milk which 

 should not be overlooked. I allude to the light essential oils 

 derived from the grasses or other herbage on which the cows 

 feed. These oils have attracted but little attention from 

 dairymen, except in some of their most obnoxious forms. 

 The essential oils of cabbage, turnips, onions, garlics and the 

 like, are offensive, and we avoid them in the food of the milch 

 cow. Those in the grasses are more agreeable, and should 

 be preserved when they safely can be. The essential oils of 

 all the foods upon which milch cows subsist are taken up in 

 their milk, and exist in it in a free state, and not like the fat 

 of the globules, in a state of emulsion. They enter largely into 

 the flavor of milk, butter and cheese. When derived from 

 the sweet-scented grasses, they give a delicious aroma to the 

 products of milk, which epicures are often willing to pay a 

 high price for. Like the animal oil I have just described, 

 they stimulate all the changes in milk and its products, and 

 however agreeable they may be, are consequently unfavorable 

 to keeping quality. 



The most of these flavoring oils are so light that they can 

 be easily driven away by heat, but not all of them. The 

 lighter varieties may be thus expelled from milk by heat, or 



