Purification of Oxalic Acid.
Commercial oxalic acid was heated with a fifteen percent solution of hydrochloric acid until all was dissolved. The solution was then warmed for twenty four hours. On cooling, crystals of oxalic acid separated out and these were washed with a little cold water to remove the mother liquor. They were then dissolved in hot ninety-five percent alcohol and allowed to crystallize slowly on cooling. The acid was next crystallized from ether in which it is only sparingly soluble. After this it was boiled with water until the odor of ethyl acetate had disappeared. Finally it was recrystallized three times from water and dried in the air at ordinary temperatures.