Contractions. - Merc-dulc. Mr-d.

Synonym. - Hydrargyri Subchloridum (P.B.).

Present name. - Mercurous Chloride. HgCl.

Subchloride of Mercury. Calomel.

This may be obtained from the manufacturing chemists, and washed with boiling distilled water on a calico filter, until the filtrate ceases to be darkened by a drop of Sulphide of Ammonium. It should be preserved from the light.

Characters and Tests. - A dull-white, heavy, and nearly tasteless powder, rendered yellowish by trituration in a mortar; insoluble in water, spirit, or ether. Digested with solution of Potash, it becomes black; and the clear solution, acidulated with Nitric Acid, gives a copious white precipitate with Nitrate of Silver. Contact with Hydrocyanic Acid also darkens its colour. It is entirely volatilized by a sufficient heat. Warm ether which has been shaken with it in a bottle leaves, on evaporation, no residue.

Preparation. - Trituration.

Reference to Horn. Proving. - Noack and Trinks.

Proper forms for dispensing. - lx to 3, Trituration only. 4, dilute Tincture only. 5 and upwards, Tincture, Pilules, or Globules.