OXALIC ACtb. 289 



the neighbouring' countries, where it is prepared in 

 large quantities. 



Pure oxalic acid may be extracted from numerous 

 substances, both animal and vegetable, by distillation 

 with nitric acid. Bergrnann was the first who obtained 

 this acid from sugar, which affords it in abundance 

 when treated with nitric acid. One ounce of lump 

 sugar, coarsely pulverized, is gradually added to six 

 ounces of nitric acid, in a stoppered retort; a gentle 

 heat is applied during" the solution, and the acid is 

 distilled off, till what remains in the retort has a 

 sirupy consistence ; this will form regular crystals of 

 oxalic acid, amounting to fifty-eight parts for every 

 one hundred parts of sugar*. 



Berthollet remarked, in the course of his experi- 

 ments, that the quantity of oxalic acid obtained from 

 vegetable matter, treated in a manner similar to the 

 sugar, was proportionate to their nutritive qualities. 

 Deyeux, having cut the hairs of the chick-pea, found 

 that they gave out an acid liquor, which proved on 

 examination to be an aqueous solution of pure oxalic 

 acid. Proust and other chemists had before observed, 

 that the shoes of persons walking through a field of 

 chick-peas were corroded -f\ 



Oxalic acid crystallizes in quadrilateral prisms ; but 

 if produced rapidly, the crystals take the form of small 

 irregular needles. They effloresce in dry air, but 

 attract a little humidity in damp weather. They are 

 soluble in their own weight of hot water, and in 

 double that quantity of cold water. Their acidity is 

 so great, that when dissolved in 3,600 times their 

 weight of water, the solution reddens litmus paper, and 

 is perceptibly acid to the taste }. Oxalic acid acts as 



* The acid may equally be obtained from raw sugar, but will, 

 in this case, require some subsequent process for its proper puri- 

 fication. 



f Ure's Dictionary of Chemistry. J Ibid, 



2 c 



