88 MATERIA MEDIC A AND THERAPEUTICS. 



ACTION AND USES. 

 1. IMMEDIATE LOCAL ACTION AND USES. 



Externally. Mercury in the form of the acid solution of 

 the nitrate is a powerful caustic, employed to destroy growths 

 on the skin, such as lupus^ "but must be used with caution. 

 The perchloride applied in weak solutions is not absorbed, but 

 acts destructively on organisms on or in the skin, such as those 

 of ringworm. Stronger solutions cause inflammation of the 

 skin, and concentrated solutions are caustic ; but neither effect 

 is surgically employed. A weak solution (gr. \ to the oz.) is 

 used as a disinfectant and stimulant to ulcers, acting like 

 other metallic salts (see pages 60 and 64), at the same time 

 being absorbed, and producing the specific effects of the metal. 

 Mercury itself, and most of the other preparations, cause little 

 or no irritation of the skin, unless rubbed into it for some time. 



The various methods of administering mercury locally must 

 here be noticed. 



(1) In the form of the ointment, metallic mercury may be 

 applied by inunction, i.e. rubbed into a soft part of the skin. 

 Thus applied, mercury undoubtedly enters the blood ; but it 

 has been contended that the metal is not admitted by the skin, 

 but through the lungs, in the form of the vapour arising from 

 the heated body smeared with the ointment, or even in small 

 particles by the mouth. Fortunately, the question is of no 

 practical importance, the fact remaining that the system can be 

 quickly brought under the influence of mercury by inunction. 

 The non-officinal oleate painted on the skin quickly conveys the 

 metal into the system. 



(2) The subchloride (calomel) may be administered by 

 fumigation. The vapour of calomel, rising from a vessel heated 

 by a lamp, is conducted to a part or to the whole of the surface 

 of the body of the patient, and there allowed to settle as a fine 

 deposit of the salt. The effect is increased by simultaneous 

 diaphoresis, induced either by the vapour of water or by such a 

 drug as jaborandi. 20 gr. of calomel may thus be fumigated, 

 during a sitting of twenty minutes. The same doubt exists as to 

 the precise way in which the calomel thus applied enters the 

 blood. 



(3) As a bath of dilute solutions of the perchloride, say 3 dr. 

 to 30 gallons of water, with 1 dr. of hydrochloric acid. 



(4) Mercurials may be dusted on to the raw surface of a 

 blistered portion of the skin, or soft syphilitic growths (con- 

 dylomata) the endermic method, when it is rapidly absorbed. 



