CARBOHYDRATES, ACIDS, FATS, OILS 83 



a room, some are liquid and some are solid, olein belong- 

 ing to the former class, and palmatin and stearin to the 

 latter. Butter, lard, and tallow differ in hardness at a 

 given temperature, and it may easily be discovered that 

 their melting-points are not the same. As the animal 

 body fats are in all cases chiefly mixtures of olein, palma- 

 tin, and stearin, stearin and palmatin 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. Stearin melts at 71.7° C. and palmatin at 

 62° C. Tallow, having much more stearin than lard and 

 less olein, is consequently much more solid on a hot day. 



The composition and physical properties of the fat 

 from a beef animal seem to vary according to the age of 

 the animal and the locality of the body from which the 

 fat is taken. Fat from an old animal melts at a lower 

 temperature than that from a young animal, and the 

 same is true of fat taken from the outside of the body as 

 compared with that taken from the inside. Fat from 

 the herbivora is in general harder than that from the 

 carnivora. 



114. Milk -fat, — This contains not only the three 

 principal fats, but also the others mentioned, butyrin, 

 caprion, caprylin, caprin, lam-in, 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. 

 These special butter-fats are liquid at ordinary tempera- 

 tures. 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. 



