One of the important salts of soda— the phosphate — has been considered under the head of phosphates. The soda salts are to be preferred in the alkaline treatment of stomach-diseases, but the potash salts when it is desired to promote oxidation in the system, or to alkalinize the urine. The urate of soda is insoluble. In case of excess of acid or acid indigestion, the use of soda after meals is very effective; but, while the immediate result is good, the after-effect is to increase the production of acid. Those who habitually take sodium bicarbonate for acid indigestion suffer severely from acidity. Taken before meals, or on an empty stomach, soda bicarbonate is useful in atonic dyspepsia, to increase the acid of the gastric juice. Acute indigestion, with vomiting, especially if the vomited matters are very acid, and there is burning at the epigastrium, may be quickly relieved by the effervescing powder. The acid diarrhoea of children is relieved by the bicarbonate of sodium. This salt may be utilized as an emetic in narcotic stupor when other emetics fail to act. The author has known this method to succeed in opium narcosis. A half to a drachm of bicarbonate in solution in water is swallowed or thrown into the stomach by the pump, and this is followed immediately by a similar quantity of tartaric acid. Brisk effervescence ensues, and the contents of the stomach are evacuated. In intussusception, the same expedient has been practiced with success. The solution of bicarbonate of sodium is thrown into the rectum, and is followed by the acid. Strong pressure must be made on the anus; the gas forces the bowel back through the ileo-caecal valve and thus relieves. A stomach or bowel much softened by inflammation, or weakened by ulceration, is a contraindication of such an expedient.

In the treatment of the febrile state, and to lessen the acidity of the urine, the soda salts have been proposed as substitutes for the potash salts. The researches of Laborde, Guttmann, Podcopaew, and others, have shown that the former do not have the same powers as the latter, and that therefore the substitution can not be made successfully, although the difference is one of degree, rather than of kind.