Fats or Oils 91 



properties. At the ordinary temperature of a room 

 some are liquid and some are solid, olein belonging to 

 the former class and palmatin and stearin to the latter. 

 It is a matter of common observation that butter, lard 

 and tallow differ in hardness at a given temperature, 

 and by the use of a thermometer it may easily be dis- 

 covered that their melting points are not the same. As 

 these animal fats are in all cases chiefly mixtures of 

 olein, palmatin, and stearin, stearin being a solid at 

 ordinary temperatures, and olein a liquid at anything 

 above the freezing point, it is evident that the relative 

 proportions of these compounds will affect the ease of 

 melting and the hardness of the mixtures of which they 

 are a part. Tallow having more stearin than lard and 

 butter and less olein, is consequently much more solid 

 on a hot day. 



Milk fat contains not only the three principal fats 

 but also the others mentioned, butyrin, caproin, caprylin, 

 caprin, laurin and myristin, in small proportions, and 

 these latter tend to give butter certain properties that 

 distinguish it from the other animal fats, which are 

 almost wholly palmatin, olein and stearin. Doubtless 

 the flavor, texture and resistance of butter to the effects 

 of heat are much influenced by the proportions of the 

 numerous fats it contains, but there is much connected 

 with this subject of which we are still ignorant. 



Free, fatty acids exist in nature. They are not found 

 in butter, lard and tallow unless these substances have 

 undergone fermentations, or, as we say, have become 

 rancid. The characteristic flavor of strong butter is due 

 to free butyric acid, which, because of fermentations, 



