11)09.] PUBLIC DOCUMENT — No. 31. 121 



The metliods that follow will be treated under the following 

 headings : — 



1. Saponification (Koettstorfer) number. 



2. Acid number. 



3. Ether (ester) number. 



4. Calculated data from saponification, acid and ether numbers. 



5. Reiehert-Meissl number. 



(a) Mean molecular weight. 

 (6) Neutralization number. 



6. Soluble fatty acids. 



(a) Neutralization number. 

 (6) Mean molecular weight. 



7. Insoluble fatty acids and luisaponifiable matter, 



(a) Neutralization number. 



(b) Mean molecular weight. 



(c) Iodine number. 



8. Calcvdated data from the fatty acids. 



9. Iodine number. 



10. Calculated data from the iodine number, 



11. Neutral fat and unsaponifiable matter. 



12. Unsaponifiable matter. 



1. Saponification (Koettstorfer) N^ijmber. 



The saponifieation number indicates the milligrams of po- 

 tassinm hydrate required for the complete saponification of 1 

 gram of an oil, fat or wax. 



Reagents. — Alcoholic potash solution, 40 grams of potas- 

 sium hydrate, free from carbonate, to 1,000 cubic centimeters 

 of 95 per cent, alcohol,^ free from acid and aldehyde. The 

 solution should be allowed to stand at least twenty-four hours 

 and filtered immediately before use. 



Ninety-five per cent, alcohol, free from acid and aldehyde. 



"N/ 2 hydrochloric acid solution. 



Phenolphthalein solution, 1 gram to 100 cubic centimeters 

 of alcohol, neutralized. 



Method. — Into a 300 cubic centimeter Erlenmeyer flask are 



1 All alcohol used as a solvent in fat analysis or in preparation of the reagents should be 

 treated several days with caustic lime and redistilled. This insures the removal of acid, 

 aldehyde and a portion of the water. The distillate should be preserved in glass and pro- 

 tected from direct sunlight. Such alcohol permits of a more distinct end reaction in titra- 

 tion. A very dry alcohol sometimes requires the addition of a small quantity of water in 

 the preparation of alcoholic potjish. 



