240 



III. CHEMISTRY OF NEUTRAL FATS 



Olive and lard oils are appreciably lower (1.467), while the high-melting 

 fats have values from 1.452 (lard) to 1.441 (coconut oil) at 60°C. 



20 40 



IODINE NUMBER 



60 



80 



Fig. 4. The relationship between the refractive indices 

 and iodine numbers of some fats.'^ 



1.4560 



1-14640 



CC 



o 1.4520 



1.4500 



POINT 



r'ig. 5. The rehitionship between the meUiiig points of fats and their 

 refractive indices. '^^ 



(4) Saponification Number 



The saponification value furnishes a measure of the average length of the 

 fatty acid chains which make up any given fat. It is defined as the 

 number of milligrams of potassium hydroxide necessary to saponify one gram 

 of fat or oil. It is also sometimes referred to as the Koettstorfer number, 

 after the scientist who first employed this constant.^-'' 



The saponification number is inversely proportional to the molecular 



326 J. Koettstorfer, Z. anal. Chem., 18, 199-207 (1879). 



