68 



MILK PRODUCTS. 



somewhat; this may be controlled, and the operation 

 hastened, by shaking the flask. When all the water 

 has been driven off, the liquid will cease to boil, and if 

 the heat and agitation be continued for a few moments, 

 complete saponification will be effected, the mixture 

 becoming perfectly clear. The whole operation, exclu- 

 sive of weighing the fat, requires less than five min- 

 utes. The flask is then withdrawn from the heat and 

 the soap dissolved in 1 35 c. c. of water. The first por- 



tions 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, s c. c. of the 

 dilute sulfuric acid are added, a piece of pumice drop- 

 ped in and the liquid distilled until 1 10 c. c. have been 

 collected. The condensing tube should be of glass, 



