680 GENERAL THERAPEUTIC MEASURES 



solution of lead acetate, make a cheap and efficient cooling 

 application for external use in the treatment of bruises and 

 sprains. The paste should be removed as quickly as it 

 dries. 



Refrigerants. — Certain medicines either produce a sub- 

 jective feeling of coolness or actually cause it, applied exter- 

 nally and given internally. The subjective sensation is due 

 to some inexplicable action on the local nerve supply. Some 

 are stimulants and astringents, and diminish the circulation 

 in the part. Externally, acetate of lead, chloride of am- 

 monium, nitrate of potash, and vinegar, are used most 

 frequently as refrigerants. 



The mineral acids and salts of potassium knd sodium, 

 especially potassium nitrate, are administered more com- 

 monly, internally, both for their cooling effect and to allay 

 thirst. 



HEAT. 



Water at a moderate degree of heat — what is termed 

 lukewarm — L e., 86° to 95° F., applied to the body, stimu- 

 lates the action of the skin, relaxes peripheral vessels and 

 diminishes nervous excitability, pain and spasm in neigh- 

 boring parts. Water at a temperature of 112° to 120° F. 

 contracts blood vessels of underlying parts, relieving con- 

 gestion and pain. Such a degree of heat resembles cold in 

 its effect, and they may often be used interchangeably. Still 

 stronger heat has much the same effect as excessive cold, 

 only acting more quickly, causing dilatation of the vessels, 

 pain, inflammation and destruction of tissue. The action of 

 powerful heat on the whole body, or upon single organs, is 

 similar to that of counter-irritants. Mild, moist heat is 

 beneficial in the treatment of wounds in poorly vascular 

 parts where there is a tendency to indolent granulation, as 

 about the feet in horses. Again, in low grades of inflamma- 

 tion with induration, as in strains of tendons, where mod- 

 erate heat tends to stimulate the circulation and hasten 

 absorption. In the treatment of abscess and burns, with 



