CHAPTER IX 

 FATS 



Fats occur very widely distributed in the plant and animal king- 

 doms, and constitute the third general class of food-stuffs. In plant 

 organisms they are to be found in the seeds, roots, and fruit, while each 

 individual tissue and organ of an animal organism contains more or less 

 of the substance. In the animal organism fats are especially abundant 

 in the bone marrow and adipose tissue. They contain the same ele- 

 ments as the carbohydrates, i.e., carbon, hydrogen, and oxygen, but 

 the oxygen is present in smaller percentage than in the carbohydrates 



FIG. 56.^-BEEF FAT. (Long.) 



and the hydrogen and oxygen are not present in the proportion to form 

 water. 



Chemically considered the fats are esters 1 of the tri-atomic alcohol, 

 glycerol, and the mono-basic fatty acids. In the formation of these fats 

 three molecules of water result. This water arises by the replacement 

 of the H's of the carboxyl groups of the three fatty acid molecules by 

 the glycerol radical, thus yielding the following type of formula. In 

 this case the combination is with palmitic acid 



CH 2 



CH OOCCi 6 H 3 i 



I 



CH 2 OOCCi 5 H 3 i 



1 An ester is an acid, one or more of whose acid hydrogens is replaced by an organic 

 radical. 



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