Phelps and Hubbard — Use of Succinic Acid. 211 



Art. XXI. — The Use of Succinic Acid as a Standard in 

 Alkalimetry and Acidimetry / by I. K. Phelps and J. 

 L. Hubbard. 



[Contributions from the Kent Chemical Laboratory of Yale Univ. — cliv.] 



Succinic acid as a standard in alkalimetry and acidimetry 

 has bad an extended use for some time. We are not aware 

 that the best methods of preparation of pure material for such 

 a purpose, or the limits of accuracy of succinic acid in such a 

 procedure, have been recorded. We give in detail below work 

 concerning these points. 



To determine the strength of the solution of ammonium 

 hydroxide used in this work in neutralizing definite weights of 

 succinic acid, a solution of hydrochloric acid, approximately 



— , was made up by diluting in the usual way with distilled 



water pure hydrochloric acid. The solution of hydrochloric 

 acid was standardized by precipitating in a volume of 250 cm3 

 definite portions of it held in a platinum dish with silver nitrate 

 in excess in presence of a few drops of nitric acid, filtering 

 off the precipitate allowed to stand twenty-four hours, after 

 cooling to zero centigrade to remove from solution traces of 

 silver chloride,* filtering off on asbestos under pressure in a 

 perforated platinum crucible, rinsing with water cooled to zero, 

 drying at 100° C, and weighing after cooling in a desiccator. 

 The solution of ammonium hydroxide was titrated against the 

 solution of hydrochloric acid, using tincture of cochineal as the 

 indicator, and by diluting with distilled water in suitable 

 amounts was made of such strength that one cubic centimeter 

 corresponded exactly to one cubic centimeter of the hydro- 

 chloric acid solution. 



Succinic acid was prepared in four different ways — by the 

 hydrolysis of the pure ester, by hydration of the pure anhy- 

 dride, by crystallization of the acid from a solution of the suc- 

 cinic acid of commerce in hot water, and by crystallization of 

 the acid from the solution of the acid of commerce in hot 

 water containing nitric acid. 



From purified succinic ester, boiling at 213° - 3- - 5 C. under a 

 barometric pressure of Y49 mm , pure succinic acid was obtained 

 by boiling it for four hours on a return condenser with nitric 

 acid and water in these proportions — 20 cm3 of succinic ester, 

 200 cm3 of water, three drops of nitric acid. This solution was 

 evaporated to crystallization, and, after filtering off from the 

 mother liquor, the solid product was recrystallized from distilled 

 water. These crystals were dried carefully in the open air to 

 constant weight, and, it was found that on standing over sul- 



* W. A. Roth, Zeitschr. f. Angew. Chem., xvii, 716. 



