ANTACID AND ALTERATIVE 191 



alkaline, not unpleasant taste, is soluble in about ten parts 

 of cold water, and is distinguished from the carbonate by its 

 feeble alkalinity, and its giving a colourless instead of a 

 coloured precipitate with corrosive sublimate. Soda water, 

 as ordinarily sold, is simply aerated water, but it should 

 contain in every pint thirty grains of bicarbonate, and be 

 saturated with carbonic acid gas, dissolved under pressure 

 of four atmospheres. 



ACTIONS AND USES. Sodium carbonate and bicarbonate are 

 antacids, expectorants, and diuretics. They differ only in 

 the degree of their action, and resemble the corresponding 

 potassium salts. They increase the alkalinity of the blood, 

 promote secretion of bile, assist in the elimination of mucus, 

 and exert a slight laxative effect. 



MEDICINAL USES. Small doses given a quarter to half an 

 hour before meals improve the secretion of gastric juice in 

 many cases of dyspepsia. (See Potassium Carbonate.) 

 Given with or after food, they aid the emulsification and 

 digestion of fats, and neutralise the acid of the gastric juice, 

 as well as any acid produced by excessive fermentation of 

 food. They are hence sometimes serviceable in relieving 

 indigestion and flatulence, their efficacy being increased by 

 administration with aromatics or stimulants. Calves fed 

 on stale skim milk, and suffering from atonic dyspepsia, are 

 often relieved by one to two drachms of sodium bicarbonate 

 and 30 grains of bismuth carbonate, dissolved in each meal 

 of milk. Hsemoglobinuria has been successfully treated 

 with half a pound to a pound sodium bicarbonate daily 

 given in doses of two ounces every hour. Normal alkalinity 

 of blood and muscle is believed to be secured, and further 

 solution of haemoglobin arrested (Dieckerhoff). They are 

 antidotes in poisoning by mineral and other acids ; being 

 less irritant than the corresponding potassium salts, they 

 are preferred for improving the secretion of gastric juice and 

 neutralising acids in the alimentary canal, while potassium 

 carbonates are more effectual antacids in rheumatism or 

 acidity of the urine, and are more active diuretics. 



Sodium carbonate solutions applied locally lessen irrita- 

 tion of urticaria, lichen, and other skin eruptions, but are 

 not so effectual as potassium carbonates. In more chronic 



