140 Phelps and ^Yeed — Acids and Acid Anhydrides. 



after the removal of the mother liquor by filtering, was 

 recrvstallized from distilled water. After these crystals had 

 dried in the open air to constant weight, it was found that on 

 standing over sulphuric acid in a desiccator the weight remained 

 unchanged. For the preparation of succinic anhydride, com- 

 mercial succinic acid was treated with an excess of acetyl 

 chloride and heated on a water bath with a return condenser 

 at 60°, as long as bubbles of gaseous hydrochloric acid were 

 evolved from the liquid. The material, which separated out 

 on cooling, was recrvstallized from ethyl acetate. These crys- 

 tals of succinic anhydride were then washed with absolute 

 alcohol and were dried to constant weight over sulphuric acid 

 in a desiccator. 



The succinic acid used in experiments YI, YII, and YIII of 

 Table I had been dried for more than a year in a desiccator 

 containing sulphuric acid, while that used in experiments IX 

 and X of the same table had been dried for the same length 

 of time over calcium chloride in a desiccator. It is evident 

 from these experiments that succinic acid dried in desiccators 

 over sulphuric acid or calcium chloride for long periods of 

 time is unaffected. 



Owing to the considerable length of time that is taken by 

 succinic anhydride to dissolve in water even in the presence of 

 some alkali, experiments XX and XXII of Table I were 

 slightly modified. In these the solution was heated until the 

 anhydride completely dissolved before an} 7 of the alkaline 

 hydroxide was added. 



Malonic acid was prepared pure by heating for some hours 

 between 50° and 60° on a return condenser malonic ester, 

 which boiled between limits of two-tenths of a degree, with 

 water in the presence of a few drops of nitric acid. The vol- 

 ume was then concentrated, keeping the temperature of the 

 solution below 60° until crystallization began, the crystals 







Table II. 











HC1 value 



HC1 value 



Theory 



Error 





Malonic 



of NaOH 



of Ba0 2 H 2 



in terms 



in terms 



No. 



acid 



used 



used 



of HC1 



of HC1 





grm. 



grm. 



grm. 



grm. 



grm. 



I 



0*2000 



0-1404 







0-1402 



•0002 + 



II 



0-2000 



0-1403 







0-1402 



•0001 + 



III 



0-2000 



0-1402 



. 



0-1402 



•oooo ± 



IV 



0-2000 



0-1401 







0-1402 



•0001- 



Y 



0-2000 







0-1401 



0-1402 



•0001 — 



YI 



0-2000 







0-1400 



0-1402 



•0002 — 



YII 



0-2000 







0-1402 



0-1402 



•oooo ± 



nil 



0-2000 







0-1400 



0-1402 



•0002 — 





