Phelps and Hubbard — Use of /Succinic Acid. 213 



In all of the experiments recorded in the table definite por- 

 tions of succinic acid were dissolved in distilled water and into 

 the solution the ammonium hydroxide of definite strength was 

 drawn carefully from a burette until the succinic acid was 

 exactly neutralized as shown by the cochineal tincture used to 

 indicate the completion of the reaction. The experiments 

 were conducted so that the final volume in each case was 

 about 250 cm3 at the completion of neutralization of the succinic 

 acid. The succinic acid used in experiments (1), (2), (3), and 

 (4) recorded in the table was that obtained by crystallizing the 

 succinic acid of commerce from water at the boiling point, and 

 dried in the air. The material in (5) and (6) was the same 

 product crystallized from water and dried in a desiccator. In 

 experiments (7) and (8) the succinic acid used was that purified 

 by crystallizing from hot water with a few drops of nitric acid. 

 In experiments (9), (10), (11), and (12) the succinic acid used 

 was made from the purified anhydride, dried to constant 

 weight in the air. The material used in experiments (13), 

 (14), (15), and (16) was the succinic acid prepared by hydro- 

 lyzing the j)ure succinic ester boiling at 213°*3-5 C. 



It is clear from the work shown in the table that succinic 

 acid may serve admirably as a standard for work in alkalim- 

 etry and acidimetry. It is further obvious that for such work 

 succinic acid of a fair degree of purity may be prepared 

 by crystallizing the acid of commerce from water at the boil- 

 ing point, or preferably by crystallizing from water at the 

 boiling point containing nitric acid. The product obtained by 

 the hydration of the anhydride is of an excellent state of 

 purity. Succinic acid of ideal constitution may be prepared 

 by hydrolyzing the pure ester. While in every case air drying 

 of the samples is sufficient, drying in a desiccator over sul- 

 phuric acid involves no risk of the formation of the anhydride. 



Since succinic ester in a state of purity may be prepared 

 with ease, succinic acid is conveniently available as a standard 

 in alkalimetry and acidimetry. It is equally reliable with 

 the previously most valued standard — hydrochloric acid 

 standardized gravimetrically as silver chloride. 



