(Rochelle Salt.)

Origin. - Prepared by adding acid potassium tartrate to a hot solution of sodium carbonate.

Description and Properties. - Colorless, transparent rhombic prisms, or a white powder, odorless, and having a cooling, saline taste. The crystals slightly effervesce in dry air. Soluble in 1.4 parts of water, almost insoluble in alcohol.

Dose. - 30 grains to 1 ounce (2.0-32.0 Gm.) [120 grains (8 Gm.), U. S. P.].

Official Preparation

Pulvis Effervescens Compositus - Pulveris Effervescentis Compositi -Compound Effervescing Powder (Seidlitz Powder). - Each powder has of Rochelle salt, 93; of sodium bicarbonate, 31, mixed in a blue paper; and of tartaric acid, 27 grains, in a white paper.

Dose. - One or two of each dissolved separately in separate quantities of water, the solutions poured together and drunk while effervescing.