CHAPTER VI. 

 THE FATS, OILS AND LIPINES. 



These compounds are characterised physically by 

 having low melting points, a greasy feel, and by being 

 insoluble in water ; but soluble in ether, alcohol, chloroform, 

 and certain other organic solvents, and chemically by being 

 mainly composed of the radicles of the higher fatty acids. 

 A certain number of substances with the appropriate 

 physical properties have been found to belong chemically 

 to the terpenes. 



The following classification (after Gies) include all 

 those of known physiological interest : 



1. Fats. Neutral glycerides of fatty acids, solid at 



20C. 



2. Fatty oils. Neutral glycerides of fatty acids, liquid 



at 2oC. 



3. Essential oils. Volatile substances of varied chemi- 



cal nature, e.g. oil of cloves. 



4. Sterols. Alcohols of the terpene group, e.g. choles- 



terol. 



5. Waxes. Esters of sterols and fatty acids, e.g. bees- 



wax and spermaceti. 



6. Phospholipins or phosphatides. Compounds of 



fatty acids containing phosphorus and nitro- 

 gen, e.g. lecithin, kephalin. 



7. Galactolipins or cerebrosides. Compounds of fatty 



acids, galactose and a nitrogenous complex. 



The fats and fatty oils are glycerol esters of the higher 

 fatty acids. 





