6 FATS, OILS, AND WAXES 



the alleged occurrence in natural fats of acids with an uneven 

 number of carbon atoms has in every case, so far recorded, 

 been refuted on careful re-examination. 



It appears probable, moreover, that all naturally occurring 

 fatty acids have a straight and not a branched carbon chain, 

 so that it is open to question whether the iso-huty\ acetic acid 

 which is said to have been found in fats was not, in reality, 

 normal caproic acid of the formula CH3(CH2)4COOH. 



Besides acids of the fatty series whose general formula is 

 CnHgnOg, acids belonging to several other series, poorer in 

 hydrogen than the above, are found in fats. The simplest 

 example of such a series of acids is furnished by the acids of 

 the Oleic series, the members of which differ from the corre- 

 sponding members. of the fatty acid series in having two atoms 

 of hydrogen less. 



Some of the more important acids of this group are given 

 below. 



I. Acids of the Oleic or Acrylic series. 



General formula CnHgn _ o^a- 



CjHgOa Tiglic acid 



C18H34O2 Oleic acid 



CigHg^Oa Elaidic acid 



C18H34O2 Iso-oleic acid 



C22H42O2 Erucic acid 



C22H42OJ Brassidic acid 



The most widely distributed of these acids is undoubtedly 

 oleic acid, which, in the form of its glyceride triolein, 



Ci7H33COOCri5, 



C„H33COO 



in 



C„H33COOCH2 



forms an important constituent of most vegetable and animal 

 oils. 



2. Acids of the Linolic series. 



General formula CnHgn _ 4O2. 



(a) Open chain compounds, CigHgaOg Linolic acid and its various 



isomers. 



(b) Cyclic compounds, CigHggOa Hydnocarpic acid. 



CjgHggOg Chaulmoogric acid. 



