36o AN ADDRESS ON 



bichloride in inhibitory power, but very inferior to it as a germicide. And the 

 double cyanide of mercury and zinc, while admirable as an inhibitor, is very 

 feeble as a germicide ; so that we can have no security that materials charged 

 with it may not contain living organisms. Hence if gauze charged with the double 

 cyanide were applied dry to a wound, the time might come when, if the dis- 

 charge were free, the salt, in spite of its slight solubility, might be all washed 

 out of the deepest parts of the dressing ; and as soon as this should be the case, 

 living microbes contained in it would be free to develop towards' the wound. 

 In order to guard against this risk, we treat the gauze before using it with a reliable 

 germicide. That which we now use for the purpose is the i to 20 solution of 

 carbolic acid, which, besides being thoroughly effective, has the further advan- 

 tage that it soon flies off from the dressing and leaves nothing in contact with 

 the wound but the unirritating double cyanide and cotton fabric. 



And now I wish to correct a mistake I made in a former publication.^ For 

 the purpose of destroying any microbes that there might be in the gauze, I recom- 

 mended a solution of corrosive sublimate, i to 4,000. Now we have seen that 

 the I to 4,000 sublimate lotion is not nearly so powerful as a germicide as we 

 then supposed. But it further appears that such power as it possesses is almost 

 entirely lost as soon as the bichloride comes in contact with the cyanide of 

 mercury and zinc, when a curious soluble triple compound - is formed which has 

 extremely slight germicidal action.^ The triple salt seems also to be highly 

 irritating ; and thus, when we used the bichloride of mercury, we failed almost 

 entirely to obtain the object for which we employed it, and at the same time 

 lost some of the goodness of the double cyanide, part of which was washed out 

 in the process, while the resulting solution might cause troublesome irritation. 

 Soon after I first described this dressing, a surgeon at one of our hospitals came 

 to me and said he had been using it, and found great inconvenience from it. 

 He had applied it to a scalp wound, and the whole of the skin covered by the 

 dressing was excoriated. I found he had applied it soaking wet with bichloride 

 lotion, and we are now able to understand the irritation that resulted. 



It is quite unnecessary to have the gauze wet with the i to 20 carbolic lotion ; 

 mere dampness is sufficient. It may be conveniently moistened as follows : 

 The gauze is commonly sold in pieces of three or six yards, folded lengthwise 

 in eight layers. These are unrolled, and half the number to be moistened are 

 sprinkled roughly with the lotion. The wet and dry pieces are then superposed 

 alternately, and the whole rolled firmly together ; and in a few minutes the 



^ See p. 319 of this volume. 



" See Varet, Comptes Rendus, 1888, vol. cvi, p. 1080. 



^ For the determination of this fact I am indebted to my colleague, Professor Crookshank. 



