32 MATER i A MEDIC A AND THERAPEUTICS. 



ACTION AND USES. 

 1. IMMEDIATE LOCAL ACTION AND USES. 



Externally. Potash, in the form of potassa caustica, is a 

 powerful irritant and caustic, absorbing water from the 

 part to which it is applied, and converting it into a moist, 

 grey slough. It is used to destroy morbid growths, to 

 form issues, and to stimulate ulcers. Solutions of liquor 

 potassae or the carbonates neutralise caustic acids on the skin. 

 Hot dilute solutions relieve the pains of rheumatism and gout 

 when used as local baths or fomentations to the affected joints. 

 Weak compounds of potash with oli ve oil constitute soft soaps, 

 which also have antacid and cleansing properties. 



i Internally. Potash and its salts have an alkaline action, 

 and are employed as antidotes to the caustic acids ; but the use 

 of the carbonates for this purpose ought, if possible, to be 

 avoided, on account of the great development of carbonic acid. 

 In the mouth, potash checks for a moment the secretion of 

 saliva. Eeaching the stomach, it partly neutralises the contents ; 

 and liquor potassae effervescens will relieve acidity due to excess 

 of gastric juice, or to the decomposition attending indigestion. 

 Of much greater importance is the stomachic action of potash 

 given shortly before meals, when, as a dilute alkali, it is a 

 natural stimulant to the gastric follicles, increasing the flow of 



the juice, and is a sedative to the nerves. Liquor potassae and 

 bicarbonate may be used for this purpose in dyspepsia, especially 

 when there is much pain and tendency to sickness, or when 

 the further action of potash on the system is desired, as in 

 gouty, rheumatic, and calculous subjects ; but soda is more 

 commonly employed. Large doses of the bicarbonate are apt 

 to irritate the stomach. 



Some valuable saline purgatives belong to the potash 

 group, notably the acid tartrate, tartrate, and sulphate. The 

 rationale of the action of saline purgatives is -discussed in 



.Part III. In dropsy from any cause, especially ascites from 



'liver disease, the acid tartrate, in the form of Pulvis Jalapas 

 Compositus, of an electuary with honey, or of a lemonade, may 

 be used to remove the water by the bowels, its hydragogue 

 effect being assisted by its action as a diuretic. 



2. ACTION ON THE BLOOD AND ITS USES. 



Potash is freely absorbed into the blood in the form of 

 ^ salts, and there acts both on the plasma and red corpuscles, 

 increasing the natural alkalinity of the former, and improv- 

 ing the quality and increasing the number of the latter when 



