ON SUBCUTANEOUS SURGERY. 9 



inflamed surface was consequently exposed to the air ; a sensa- 

 tion of smarting, heat, and pricking was felt. The blistered 

 part was covered with a small glass jar, mto which nitrogen 

 gas was introduced from another jar communicating with it 

 by means of a stopcock, and an elastic tube. In two or three 

 minutes the smarting and pricking were removed, a sensation 

 of comfortable warmth was experienced when the attention 

 was directed to it, but at other times, there was hardly any 

 sensation. The nitrogen was applied for twelve minutes, and 

 the relief continued to the end of the application. The nitro- 

 gen gas was then displaced by oxygen from another jar. 

 There was a little return of pricking at the moment when 

 the gas was introduced. The oxygen was continued for ten 

 minutes, during which time the pricking and warmth remained. 

 The glass being removed, a current of oxygen was applied 

 from the end of a tube and the part smarted a little more after- 

 this. The oxygen was applied again in the jar ; it occasioned 

 a sensation of heat to discomfort without smarting or pricking. 



After the blister had been exposed for a short time to the 

 common air, hydrogen gas was applied in a jar, in the same 

 manner as the other gases; in the trial, smarting and pricking 

 diminished. 



After the blistered surface had been again exposed to the 

 air for a short time, carbonic acid gas was applied. It caused 

 decided increase of smarting, which changed to a sense of heat. 

 In three minutes the smarting was quite gone, and the heat 

 had subsided to a gentle warmth. The above experiments 

 confirm the observations of Ingen Housz. The}^ show that nitro- 

 gen, hydrogen, and carbonic acid gases relieve and prevent 

 the smarting which atmospheric air causes on an abraded 

 surface, the last of these gases, however, having an iri'itant 

 effect in the first instance, before its soothing or narcotic 

 influence is develoiped. Pure oxygen gas caused more pain 

 than atmospheric air. Although these experiments were per- 



