IMPROVED METHODS FOR FAT ANALYSIS. 



95 



Fatty Acids and Glycerides. 



Total fatty acids. 



Saponification (Koettstorfer ') Number. 



The saponification number indicates the number of milligrams of potas- 

 sium hydroxide required for the complete saponification of 1 gram of an 

 oil, fat or wax. 



Reagents. — Alcohol : * redistilled, free from acids and aldehydes. 



' The free soluble and insoluble acids should not be calculated to glycerides. 



' Are considered as constituting a portion of the soluble acids. 



' Ztschr. Analyt. Chem., 18, pp. 199-207, 431-437 (1879). 



* To purify alcohol for use as a solvent or reagent in fat analysis, 5 gallons are treated with at 

 least 10 grams of silver nitrate, thoroughly shaken, and allowed to stand to insure oxidation of 

 aldehydes; then, with 1,000 grams of calcium oxide (caustic), repeatedly shaken for several days 

 to remove acids and a portion of the water, filtered and redistilled. Fractionation is necessary if 

 the boiling point exceeds a range of 1° C., the distillate should be preserved in glass and protected 

 from sunlight. 



