BUTTER 87 



with alcohol and then with ether, and thoroughly 

 dried by heating in the water-oven. After 

 cooling, it is allowed to stand for about fifteen 

 minutes and weighed. (In ordinary operation 

 this preparation of the flask may be omitted.) 

 A pipet, graduated to 5.75 c.c, is heated to about 

 60° and filled to the mark with the well-mixed 

 fat, which is then run into the flask. After 

 standing for about fifteen minutes the flask and 

 contents are weighed. 20 c.c. of the glycerol- 

 soda are added and the flask heated over the 

 Bunsen burner. The mixture may foam some- 

 what; this may be controlled, and the operation 

 hastened by shaking the flask. When aU the 

 water has been driven off, the liquid wiU cease 

 to boil, and if the heat and agitation be continued 

 for a few moments, complete saponification will 

 be effected, the mass becoming clear. . The whole 

 operation, exclusive of weighing the fat, requires 

 about five minutes. The flask is withdrawn from 

 the heat and the soap dissolved in 135 c.c. of water. 

 The first portions of water should be added drop 

 by drop, and the flask shaken between each 

 addition in order to avoid foaming. When the 

 soap is dissolved, 5 c.c. of the dilute sulfuric acid 

 are added, a piece of pumice dropped in (this 

 must not be omitted), and the liquid distilled 

 until no c.c. have been collected. The con- 

 densing tube should be of glass, and the distilla- 

 7 



