Called sal soda, or washing soda. Transparent colorless crystals, soluble in two parts of water. Its effects are similar to those of the potassium carbonate, but it is rarely used medicinally. In large quantities it is an irritant poison for which oils and acids are the antidotes. It is an excellent material for cleaning glass, china, and wood. Poured in strong solution into drains and water-pipes it carries away grease. It will remove the stains made by bichloride of mercury on china and glass.

Sodii Bicarbonas. Sodium Bicarbonate

Soluble in 12 parts water (saturated solution). Sodium bicarbonate has a soothing action in burns, eruptions, and irritation of the skin. Dose, as an antacid, gr. x.-xx. (0.65-1.3 Gm.) It is pleasantly administered in carbonated water - Seltzer or Vichy.

Pulvis Effervescens Compositus. Compound Effervescing Powder. Seidlitz Powder.

Seidlitz powder is put up in two packets, a white paper containing gr. xxv. of tartaric acid (the acid of grapes), and a blue one containing gr. xl. of sodium bicarbonate and gr. cxx., or 3 ii., of Rochelle salt. They are dissolved separately in very cold water, the acid in one or two ounces, and the salt in five or six. They are then poured together and taken after the first escape of gas, while still effervescing. It is hardly necessary to say that they should not be mixed at a distance from the patient, but at his side and at the precise moment when he is ready to take the dose. The glass must be large, to allow for the effervescence, and it is well to have a saucer under it, to avoid the annoyance of having it effervesce over the top and sides. The powders must be kept dry. Exposed to the air they become damp and lose their effervescing quality. Seidlitz powder is refrigerant and laxative, and should be given in the morning on an empty stomach. One powder is usually sufficient for a dose, acting in from three to six hours.