BUTTER. 73 



The distillation. After the fatty acids are complete- 

 ly melted, which can be determined by their forming a 

 transparent oily layer on the surface of the water, the 

 flask is cooled to room temperature, and a few pieces 

 of pumice stone added. The pumice stone is prepared 

 by throwing it, at a white heat, into distilled water, 

 and keeping it under water until used. The flask is 

 now connected with a glass condenser, slowly heated 

 with a naked flame until ebullition begins, and then 

 the distillation continued by regulating the flame in 

 such a way as to collect 1 10 c. c. of the distillate in, as 

 nearly as possible, thirty minutes. The distillate 

 should be received in a flask accurately graduated at 

 no c. c. 



Titration of the volatile acids. The 1 10 c. c. of dis- 

 tillate, after thorough mixing, are filtered through 

 dry filter paper and collected in a flask marked 

 at 100 c. c. 100 c. c. of the filtered distillate are 

 poured into a beaker holding from 200 to 250 c. c., 

 0.5 c. c of phenolphthalein solution added, and decinor- 

 mal barium hydroxid run in until a red color is produced. 

 The contents of the beaker are then returned to the 

 measuring flask to remove any acid remaining therein, 

 poured again into the beaker, and the titration contin- 

 ued until the red color produced remains apparently 

 unchanged for two or three minutes. The number of 

 cubic centimeters of decinormal barium hydroxid re- 

 quired should be increased by one-tenth. 



Many other methods of detecting butter adultera- 

 tion have been proposed. The specific gravity of the 



