174 POTASSIUM SALTS 



ACTIONS AND USES. The alkalies comprise salts of potas- 

 sium, sodium, lithium, and ammonium. They are the 

 chemical opposites of the acids. They neutralise acids, 

 dissolve albumin, and saponify fats, and in virtue of these 

 properties are irritant and caustic. They are destitute of 

 astringency, and in dilute solution relax and soothe the 

 tissues with which they come into contact. They are also 

 used to neutralise excessive acidity developed from undue 

 fermentation, in which case being administered an hour after 

 eating. They promote elimination of lactic acid in rheumat- 

 ism, and to some extent prevent the precipitation of uric 

 acid in the bladder. The alkalies and their salts in solution 

 exert osmotic effects in contact with animal membranes, and 

 hence promote both catharsis and diuresis. When absorbed, 

 they increase the alkalinity of the blood and urine, encourage 

 oxidation processes, and promote other alterative effects. 



Potassium salts are protoplasmic poisons when applied 

 directly to the tissues, and in sufficiently strong solution for 

 a sufficient time they destroy muscles, nerves, and nerve- 

 centres. They are more soluble, more readily absorbed and 

 diffused, and more quickly excreted than sodium salts, but 

 less rapidly than those of ammonium. When a salt, such as 

 potassium chloride, in which the acid ion has little action, is 

 injected intravenously or subcutaneously the characteristic 

 action of potassium is produced. It attacks especially the 

 heart, causing paralysis of that organ, depresses the whole 

 central nervous system and paralyses the reflex centres of 

 the cord. Large doses cause a rapid fall of blood pressure 

 and pulse rate ; whilst general symptoms are great depres- 

 sion, muscular weakness, and quick breathing. 



Given by the mouth these actions are not produced, for 

 the drug is excreted as fast or faster than it is absorbed. 

 Thus potassium salts given per os exert only ' salt action ' 

 (q.v.), except where the acid ion as in the case of the bro- 

 mide or iodide is itself physiologically active. 



They occur in plants and animals, and are essential con- 

 stituents of the food of both. Their removal from the food 

 of dogs impairs nutrition and growth more decidedly than 

 deprivation of the corresponding sodium salts. In animal 

 bodies potash salts occur chiefly in the solid textures, notably 



