Sensory Effect of Hypertonic Salt Solutions. 147 



detected. A number of other solutions and substances were 

 tested in the same way and all, with the exception of cocain, gave 

 similar results, the only difference being either a difference in the 

 time of onset of evidence of irritant action or in the degree of such 

 action. 



Among the substances investigated by application to abraded 

 skin areas, magnesium salts were among those that gave rise to 

 very severely painful sensations which persisted for twenty minutes 

 or more, at which time the solutions were removed. Tested in this 

 way, cocain solutions were but slightly if at all irritating, and with- 

 in a few minutes their application was followed by distinct evidence 

 of anesthesia; for example, to application of normally painful 

 mechanical stimuli, the area showed a diminished sensibility. 

 We, therefore, cannot accept Wiki's conclusions upon the evidence 

 he has presented. 



He states that isotonic solutions of the magnesium salts are 

 not without anesthetic action, but stronger solutions give more 

 intense effects. These results would speak against an infiltration 

 anesthesia such as we know can be produced by distilled water or 

 even isotonic sodium chloride solutions. But in view of our 

 results which demonstrate so clearly the pronounced irritating 

 action of hypertonic magnesium salt solutions applied to abraded 

 skin areas and complete absence of anesthetic symptoms, we are 

 inclined to interpret Wiki's observations as evidence of infiltration 

 anesthesia or inhibition of the reflexes through sensory stimulation. 



Though aware that such experiments conducted by application 

 of the agents to human cutaneous abrasions have been criticized 

 especially from the psychological standpoint, yet we would 

 emphasize their importance when carefully conducted and con- 

 trolled, for not only is it possible to conduct a large series of 

 observations in a relatively short time, but the evidence secured, 

 being direct, is final. 



Since all of the inorganic salt solutions employed (which include 

 the chlorides and sulphates of Na, K, NH 4 , Mg, and the chlorides 

 of Ca and Ba) have similar actions, the difference being, so far as 

 has been observed, a quantitative one, the action would seem to 

 be more of a physical or physical chemical than of a chemical or 

 specific nature. With hypertonic solutions the differences ob- 



