CHAPTER VII. 



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 elements as the carbohydrates, i. e., carbon, hydro- 

 gen and oxygen, but the oxygen is present in smaller percentage 

 than in the carbohydrates and the hydrogen and oxygen are not 

 present in the proportion to form water. 



FIG. 35. 



BEEF FAT. (Long.) 



Chemically considered the fats are esters 1 of the tri-atomic alco- 

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

 these fats three molecules of water result. This water may arise 

 in either of two ways. First, by the replacement of the H of 

 each of the OH groups of glycerol by a fatty acid radical, giving 

 the following formula in which R, R' and R" represent fatty acid 

 radicals, 



1 An ester is an ethereal salt consisting of an organic radical united with the 

 residue of ari inorganic or organic acid. 



