96 



MASS. EXPERIMENT STATION BULLETIN 166. 



Alcoholic potash solution : ^ 50 cubic centimeters of a saturated solution 

 of potassium hydroxide, free from carbonate, to 1,000 cubic centimeters 

 of alcohol. The alkali should be added to the alcohol slowly with agita- 

 tion in order to prevent any appreciable rise in temperature. The solu- 

 tion should be allowed to stand at least twenty-four hours and filtered 

 immediately before use. 



N/2 hydrochloric acid. 



Phenolphthalein solution: 1 gram to 100 cubic centimeters of alcohol, 

 neutralized. 



Cotton blue 6B ^ solution : 2 grams to 100 cubic centimeters of alcohol. 

 The indicator should be boiled in a flask under a reflux condenser for two 

 hours and then filtered. 



Method. — Into a 300 cubic centimeter Erlenmeyer flask are brought 5 

 grams of fat (care being taken to avoid getting any fat on the sides of the 

 flask), together with 50 cubic centimeters of alcohohc potash, ^ accurately 

 measured with a burette, 50 cubic centimeters of alcohol and several 

 glass^beads. The flask is connected with a spiral or other form of reflux 

 condenser and the solution boiled vigorously on a water bath (see Figs. 1 

 and 2) with occasional rotation until saponification is complete, — about 



Fig. 1. — Steam-heated water bath employed in the determination of saponification, 

 acid and acetyl numbers and insoluble acids. 



' Approximately 0.65 N solution. Alcoholic potash will dissolve about 0.04 gram of potassium 

 carbonate to 100 cubic centimeters, according to Holde. — Chem. Rev. Fett u. Harz Indus., 14, 

 pp. 105-107 (1907). . 



' Sodium salt of triphenylpararosaniline-trisulphonic acid. Obtained- from National Aniline 

 and Chemical Company, 100 William Street, New York, N. Y. 



3 For waxes, especially wool wax, potassium alcoholate is preferable on account of its greater 

 efliciency. The solution should be freshly prepared by dissolving 5 grams of metallic potassium 

 in 100 cubic centimeters of absolute alcohol. — Lewkowitsch, Analysis of Oils, Fats and Waxes, 

 1, p. 107 (1913). 



