Contractions. - Natr-c. Nat.

Present name. - Sodic Carbonate. Na2Co3,10H1O.

The common Soda (German, Laugensah, Sodasalz) of the shops, purified by solution in distilled water and re-crystallization.

Characters and Tests. - In transparent, colourless, laminar crystals of a rhombic shape, efflorescent, with a harsh alkaline taste and strong alkaline reaction. It imparts a yellow colour to flame, and dissolves with effervescence in diluted Hydrochloric Acid, forming a solution which does not precipitate with Perchloride of Platinum. By heat it undergoes aqueous fusion, and then dries up, losing 63 per cent. of its weight. When supersaturated with Nitric Acid it precipitates only slightly with Chloride of Barium or Nitrate of Silver. 143 grains require for neutralization at least 960 grain measures of the volumetric solution of Oxalic Acid.

Preparations. - Trituration. Solution in distilled water for lx, dilute alcohol for 1, 20 O.P. spirit for 3X, and rectified spirit for all above.

Reference to Horn. Proving. - Chr. Kr., iv.

Proper forms for dispensing. - lx to 3, Trituration. lx and 1, Solution. 3X and upwards, Tincture, Pilules, or Globules.