-20 Journal of Agricultural Research voi. xii, No. n 



EARLIER INVESTIGATIONS 



At the present writing esterification methods have so wide an appli- 

 cation and contributors to the literature on the subject are so numerous 

 that only references bearing directly on the analysis of oils and fats 

 will be cited. 



Rochleder (28) studied the action of absolute alcohol and dry hydro- 

 chloric acid gas upon castor oil in the separation of glycerol. 



Berthelot (2, p. 311-312) applied the reaction to a number of glycerides 

 and showed that esters of the fatty acids were formed in addition to 

 glycerol. 



Juillard {15, p. 239) prepared methyl and ethyl esters of dihydroxy- 

 stearic acid by boiling the acid with 10 times its weight of alcohol and 

 2 or 3 drops of sulphuric acid. 



Fischer and Speier (5) esterified various organic acids with different 

 amounts of absolute ethyl alcohol and dry hydrochloric or concentrated 

 sulphuric acid, also of methyl alcohol and hydrochloric acid and noted 

 the yield. They did not deduce a general method. 



Haller {8-1 1) heated a variety of oils and fats with twice their weight 

 of absolute methyl alcohol containing i to 2 per cent of hydrochloric 

 acid, removed the glycerol and excess alcohol with water, or preferably 

 brine, and fractionated the esters up to 194° C. (methyl caprylate) 

 at atmospheric pressure and the residual esters in vacuo. The methyl 

 oleate present in the myristic and higher fractions was removed by 

 chilling and absorption on porous plates. When complete alcoholysis 

 was not obtained, he recommended a second treatment with a new por- 

 tion of acidulated alcohol, the employment of a larger amount of alcohol 

 at the outset, or the addition of an inert solvent such as ether to facilitate 

 the reaction, particularly in the case of butter fat and of drying oils which 

 readily oxidize and polymerize. The production of a small amount of 

 aldehyde was noted in some instances. Haller neutralized the esters 

 wAth. barium carbonate or a solution of sodium carbonate and dried over 

 calcium chloride or anhydrous sodium sulphate. 



Phelps and Hubbard {18) esterified succinic acid with ethyl alcohol 

 and hydrochloric acid, and secured the greatest yield with maximum 

 dehydration. In other experiments {ig) the addition of anhydrous zinc 

 chlorid enhanced the reaction. 



Complete esterification of 50 gm. of benzoic acid {26) was obtained 

 by treating for 4 hours with 400 c. c. of absolute alcohol containing 1.25 

 per cent of dry hydrochloric acid and 10 gm. of anhydrous zinc chlorid, 

 or for 3 hours with 200 c. c. of absolute alcohol and 2 gm. of sulphuric 

 acid. 



Several other chlorids {24, p. 296-297; 20-25) proved nearly as effi- 

 cient as zinc chlorid under like conditions of operation. 



