Contractions. - Oxal. Ac. Ox.-x.

Present name. - Dihydric Oxalate. H1C2O4, 2H1O.

Oxalic Acid. For. name: German, Oxalsaure.

Prepared on a large scale by the action of caustic alkalies on sawdust. It can be readily obtained impure from the manufacturing chemists, and should be purified by solution in distilled water and re-crystallization, according to the process given in the British Pharmacopoeia, viz.: -

Take of

Oxalic Acid of commerce

1 pound;

Boiling Distilled Water

30 fluid ounces.

Dissolve, filter the solution, and set it aside to crystallize. Pour off the liquor, and dry the crystals by exposure to the air on filtering-paper placed on porous bricks.

Characters and Tests. - Colourless prismatic crystals, strongly acid, dissolving freely in water. Heated in a test-tube with strong Sulphuric Acid, it dissolves with effervescence, evolving Carbonic Oxide and Carbonic Anhydride, the former of which burns with a blue flame on approaching the mouth of the tube to a flame. Heated in a dry tube, it is entirely converted into vapour, a part of which condenses on the sides of the tube in fine transparent needles. Its solution in water gives a white precipitate with Nitrate of Silver, soluble in dilute Nitric Acid. A strong solution gives with Nitrate of Barium, on stirring with a glass rod, a granular precipitate, soluble in dilute Nitric Acid.

Preparation. - Solution in rectified spirit 1 in 10.

Reference to Horn. Proving. - Transactions of Amer. Institute, vol. i.

Proper forma for dispensing. - lx and upwards, Tincture, Pilules, or Globules.