80 
of margarine and oleine; but has a different flavour from 
other fats, in consequence of the presence of three volatile 
oils, named butyrine, caprone, and caprine. These volatile 
bodies are probably formed from the odoriferous principles 
contained in the food consumed by the cow, as we find them 
very much modified by those acrid sulphur oils which exist 
in garlic, horse-radish, turnips, &c. The amount of butter 
contained in the new milk of the cow is by no means 
uniform, its quantity at all times depending on the kind and 
quantity of food consumed, the temperature to which she is 
exposed, the amount of exercise she takes, and the character 
of the animal itself. 
All those vegetable compounds which are called elements 
of respiration, such as starch, sugar, gum, and oils, may be 
considered conducive to the formation of butter, for butter is 
merely the superfluous carbon and hydrogen of the food, 
which, like ordinary fats, remain unconsumed during respira- 
tion. Exercise, therefore, which renders it necessary for the 
cow to oxidize more carbon and hydrogen, to produce 
motion, and cold, which renders it necessary for the animal 
to burn more for the purpose of keeping up the ordinary 
temperature of its body, are both opposed to the formation 
of butter, while rest and warmth will be favourable to it. 
Butter, then, will be that constituent in milk which mainly 
supports respiration, and produces heat and motion in the 
animals consuming it; and as the quantity of respiratory 
food required by all animals which take severe exercise is 
much larger than that required for forming the organised 
tissue of the body, the presence of such a rich principle in 
milk is of the greatest importance, and is the one on which 
the young animal which consumes nothing else is mainly 
dependent for the support of these important processes. 
There is another principle, however, in milk, which is 
also of considerable consequence in this respect, namely, the 
sugar. Sugar of milk is a white crystalline solid, possessing 
