I. K. and 3L A. Phelps — Use of Zinc Chloride. 195 



distilled and collected in the receiver, cooled by a stream of 

 water striking it constantly, and then weighed. 



The pure zinc chloride of commerce was freshly fused for 

 use in the experiments. The alcohol employed was made as 

 anhydrous as can be obtained by successive treatments with 

 fresh quicklime. The alcohol containing hydrochloric acid was 

 charged with the dry gas in the proportion of ten grams to the 

 liter. The succinic acid used was in most cases the pure acid 

 of commerce, in the others, pure succinic acid made by recrys- 

 tallizing the product formed by the hydrolysis of the pure ester 

 in the presence of nitric acid. 



The result obtained in experiment (1) of the table was found 

 by heating with an acid potassium sulphate bath in the flask 

 B a known weight of succinic acid with 40 cm3 of the total 

 amount of absolute alcohol used in presence of ten grams of zinc 

 chloride at a temperature of 100° to 110°, while driving into 

 it the remainder of the alcohol in the form of vapor from 

 flask A. All vapors from the flask passed through the Hem- 

 pel column to the condenser. The Hempel column had an 

 active surface of beads of 10 om in height and a diameter of 2 cm . 

 At its lower end it was in connection with a tube 5 cm in length 

 and of 0'5 cm bore, and had an opening blown in its side l/5 cm 

 from the end. By the use of a column of this construction the 

 hot vapor is enabled to go upward while the condensed liquid 

 flows downward readily. It was found that by the use of this 

 column neither succinic ester nor succinic acid distilled in such 

 amount, if at all, that it could be detected in the liquid distil- 

 late. The impure ester in flask B, when all alcohol as vapor 

 from flask A had been passed into it, was cooled and then 

 poured into a separating funnel containing water with ice, using 

 a small amount of ether to rinse the ester from the flask, and 

 the zinc chloride was removed as far as possible. After sepa- 

 rating the ester from this solution any acid impurities were 

 neutralized with an excess of sodium carbonate in solution, and 

 the ethereal solution was then washed with distilled water. 

 The aqueous solutions in which the ester had been washed 

 were shaken out three times separately with ether. . The ethe- 

 real extracts were gathered in a 250 cm3 distilling flask connected 

 in the usual way for a vacuum distillation with a 100 cm3 distil- 

 ling flask used as a receiver. The low boiling impurities, ether, 

 alcohol, and water largely, were separated by a vacuum fraction- 

 ation, the 250 cm3 flask being heated in a bath of hot water at 

 60° finally for fifteen minutes after the manometer registered 

 15 mm and the succinic ester was then distilled and weighed. 



The procedure in case of experiments (2) and (3) was the 

 same excepting that the alcohol used was charged with hydro- 

 chloric acid in the proportion of ten grams to the liter ; and in 

 case of (3), and, also, in case of all other experiments in the 



