BUTTER. 69 



and the distillation conducted at such a rate that the 

 above amount of distillate is collected in 30 minutes. 



The distillate is usually clear; if not, it should be 

 thoroughly mixed, filtered through a dry filter, and 

 100 c. c. of the filtrate taken. To the distillate, about 

 0.5 c. c. of the phenolphthalein solution are added, and 

 the standard barium hydroxid run in from a burette 

 until a red color is produced. If only 100 c. c. of the 

 distillate have been used for the titration, the number 

 of c. c. of barium hydroxid should be increased by one- 

 tenth. 



When it is intended merely to distinguish pure but- 

 ter and pure oleomargarin it will be sufficient to meas- 

 ure into the flask three or six c. c. of the clear fat, 

 and operate upon this directly. 



A blank experiment should be made to determine 

 the amount of decinormal alkali required by the ma- 

 terials employed. With a good quality of glycerol, 

 this will not usually exceed 0.5 c. c. 



Butter (5 grams) yields a distillate requiring from 

 24 to 34 c. c. of decinormal alkali. Several instances 

 have been published in which genuine butter has given 

 a figure as low as 22.5 c. c., but such results are un- 

 common. The materials employed in the preparation 

 of oleomargarin yield a distillate requiring less than 

 l c. c. of alkali. Commercial oleomargarin is usually 

 churned with milk in order to secure a butter flavor, 

 and thus acquiring a small amount of butter-fat yields 

 distillates capable of neutralising from I to 2 c. c. of al- 

 kali. 



