Origin. - Prepared by roasting in a reverberatory furnace potassium carbonate and chrome-iron ore, with the addition of lime or chalk to prevent fusion. The potassium dichromate formed is separated by crystallization from its solution in water acidulated with sulphuric acid.

Description and Properties. - Large orange-red, transparent triclinic prisms or four-sided tables, odorless, and having a bitter, metallic taste. Permanent in the air; soluble in 19 parts of water; insoluble in alcohol.

Dose. - 1/100-1grain (0.0006-0.06 Gm.) [1/5 grain (0.01 Gm.), U. S. P.].

Antagonists and Incompatibles. - Potassium dichromate is incompatible with soluble salts of silver, mercury, and lead, and with liquor potassae, liquor sodae, and ammonia water.

Synergists. - Agents promoting waste, antiseptics, and caustics.

Physiological Action. - Externally and Locally. - In substance potassium dichromate is an irritant caustic, and, according to Miquel, an antiseptic in the proportion of 1 to 909.

Internally. - Its action is nearly identical with that of potassium chlorate, with the additional properties of an expectorant, emetic, and mild alterative.

Poisoning and treatment of poisoning do not differ essentially from those of potassium chlorate.

Therapeutics. - Externally and Locally. - Potassium dichromate is used as a caustic for warts, corns, chancres, chancroids, mucous patches, etc., and is also of considerable value as a gargle in pharyngitis.

Internally. - Frazer has recently recommended this drug in the treatment of dyspepsia and gastric ulcer, claiming that the pain, nausea, vomiting, and tenderness may be readily allayed by doses of 1/12 to 1/6 grain (0.005-0.01 Gm.), taken upon an empty stomach three times a day. In acute gastric ulcer he has perceived no benefit so far as its effect upon the hemorrhage is concerned, the most desirable action of the drug in the latter condition being derived from its antiseptic and analgesic influence.

Potassium dichromate, in doses of 1/100 grain (0.0006 Gm.) every hour or two, has proven of service in aphonia and hoarseness due to excessive action of the vocal cords or resulting from an acute cold.