274 DISEASES OF THE SKIN 



applied bountifully two or three times daily, the old powder 

 removed before applying the new, using cotton and oil. In 

 obstinate cases nitrate of silver (2 to 6 per cent.) or picric 

 acid (1.5 per cent.) followed by powders, and, when the 

 exudate is dry, by salves. 



Chronic Eczema. — Chronic eczemas are treated, contrary to 

 acute, by irritant agents. The old crusts and scales should be 

 removed with castile soap and soft water or vaselin. If water 

 is used the skin afterward should be rubbed perfectly dry. 

 If the skin is moist from exudate, apply powders, as in acute 

 eczema. Later, coal-tar products are good, such as tar oint- 

 ment (1 to 10) or tar liniment: 



If — Fix liquida and kaolin aa 1 part 



Alcohol 5 tolO " 



Creolin preparations are also indicated. The following 

 prescription has been found useful: 



I^ — Creolini 5i 



Phenoli . gss 



Plores sulph. gj 



Spts. terebinth. . . . Siv 



Liquor ammonii fortes . . _ Siij 



Kerosene . . . gxl 



M. f. emulsio, apply with brush. 



Naphthol or naphthalin salve (5 to 15 per cent.) or iodin- 

 glycerin is of value. 



^ — Tinct. iodini 1 part 



Glyeerini . . 4 " 



Salicylic acid ointment (5 to 15 per cent.) and pyrogallic 

 acid (5 to 15 per cent.) are also employed. Pyrogallic acid 

 ointment is especially useful if the skin is much thickened. 

 All of these agents tend to loosen the crusts, reduce the pruri- 

 tus, and assist in the resorption of the exudate. 



Internally mild cathartics and intestinal disinfectants 

 (calomel) assist. Fowler's solution of arsenic in horses is 

 useful. The patient should be given good care and food and 

 prevented from biting or scratching the parts. 



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