180 THE ACTION OF 



the only drugs which relieve deep-seated pain when 

 painted on or rubbed into the skin are the counter- 

 irritants. 



Full details of the experimental data for these 

 conclusions, which are accepted by the leading 

 pharmacologists, will be found elsewhere. Briefly, 

 the methods adopted were as follows. 



Strong, even dangerously strong solutions and 

 ointments containing opium, atropine or belladonna, 

 aconite, cocaine, carbolic acid, and menthol were 

 tested on the skin of the finger, and on the tongue, 

 and these were then examined to see if their sensi- 

 bility was in any way altered. The methods of 

 examining the skin of the finger were as follows. 

 Each test was applied on more than one observer 

 and after varying intervals of time. 



1. The Intolerable Temperature Test. For each 

 observer there was a certain constant temperature 

 which was just not intolerably hot, when the finger 

 was dipped into warm water for half a minute. 

 This was determined before and after applying the 

 drug under consideration. 



2. The Faradic Pain Test. The strength of current 

 was determined, before and after the application of 

 each drug, at which the damp finger first found 

 electrical stimulation by means of electrodes led 

 off from a faradic coil actually painful, the current 

 used being small at first and gradually augmented. 



3. Thermal Discrimination Test. We found that 

 we were able, by immersing the finger first in one 

 beaker of warm water and then in another, to detect 

 a difference in temperature of not less than one degree. 



