1911.] PUBLIC DOCUMENT — No. 31. 133 



should be taken to avoid heating to a higher temperature than is 

 required for solution, or to prolong the heating unduly, as it 

 will cause the formation of esters. Several minutes' boiling of 

 the different fatty acids in alcohol caused the following loss in 

 neutralization number : — 



Stearic acid, ...... 1.70 



Pahnitic acid, ........... .56 



Myristic acid, 2.24 



Laurie acid, . 89 



Oleic acid, 28 



Esterification undoubtedly causes a serious error by this 

 process of purification. Under more careful treatment the 

 change is not as rapid as shown above, but is evidently cumula- 

 tive and may even exceed the figures given. Further study may 

 warrant the substitution of a more stable solvent, such as acetone. 

 For the filtration a water or ice jacketed funnel is almost neces- 

 sary, particularly for the acids of low melting point, and suc- 

 tion is a time saver. Repeated crystallization is needed to bring 

 out the true crystalline structure and silvery luster of the leaflet. 

 Vacuum drying at a low temperature is one of the most efficient 

 means for removing adhering alcohol and traces of moisture 

 without injuring the structure. Crystallization as a whole is 

 wasteful of acids and solvent unless both are recovered, but is 

 essential for the production of a superior product. 



C. Distillation" of the Ethyl Esters ix Vacuo. 

 As ethyl esters distill freely in vacuo, the process admits of a 

 more ready application, and to products of a greater range of 

 purity, than docs a distillation of the acids. After considerable 

 experimenting it was found that the esters are easily prepared 

 by heating in an open flask equal parts (100 grams) of fatty 

 acids and alcohol, together with a small quantity (10 cubic cen- 

 timeters) of concentrated hydrochloric acid, using capillary 

 tubes to prevent bumping. The reaction requires about thirty 

 minutes, after which the excess of hydrochloric acid can be 

 removed with a scparatory funnel. The distillation is con- 

 •luctod in a .''jOO cubic centimeter " low " side neck flask, with 

 a small (8 inch) Licbic; condenser and a large size Druehl frac- 



