Poisoning by caustic soda is rare; the symptoms and treatment are the same as described under POTASSIUM. The salts of sodium resemble potassium in their action on the alimentary tract, but they are much more slowly absorbed, and much less diffusible; therefore considerable amounts may reach the small intestine and there act as saline purgatives. They are slowly absorbed into the blood, and are a natural constituent of the blood plasma, which derives them from the food. Sodium is excreted by all the mucous surfaces and by the liver and kidneys. On the latter they act as diuretics, but less powerfully than potassium, increasing the flow of water and the output of urea and rendering the urine less acid.
Therapeutics: External Use.—The liquor sodii ethylatis is a powerful caustic and is used to destroy small naevi and warts. A lotion of sodium bicarbonate is useful to allay itching. Solutions of sodium sulphite are used as mild antiparasitics. Internal U se.— Sodium chloride is occasionally used in warm water as an emetic, and injections of it into the rectum as a treatment for thread worms. A 0.9% solution forms what is termed normal saline solution, which is frequently injected into the tissues in cases of collapse, haemorrhage and diarrhoea. It forms a valuable treat ment in diabetic coma and eclampsia, acting by diluting the toxins in the blood. From this has developed the intramuscular injection
of diluted sea-water in the treatment of gastro-enteritis, anaemia and various skin affections. Sodium chloride is an important con stituent of the waters of Homburg, Weisbaden, Nauheim and Kissingen. Sodium bicarbonate is one of our most useful gastric sedatives and antacids, relieving pain in hyperchloridia. It is the constituent of most stomachic mixtures. Effervescent soda water is a mild gastric sedative. Sodium phosphate and sulphate are cholagogue purgatives and are used in the treatment of gall stones. The sulphate is the chief constituent of Marienbad and Carlsbad waters. Large doses of these salts are used to remove fluid in dropsy. Soda tartarate is purgative and diuretic, as is the citro-tartarate. These purgative sodium salts are most useful in the treatment of chronic constipation, and of the constipation associated with gout and hepatic dyspepsia. They should be dis solved in warm water and taken in the morning, fasting. In vis ceral gout and chronic catarrhal conditions of the stomach a course of alkaline waters is distinctly beneficial. Sodium salts have not the depressant effect so marked in those of potassium.