AN ADDRESS ON A NEW ANTISEPTIC DRESSING 313 



mercury kept blood-serum with only i-i 0,000th part perfectly free from organic 

 development, in spite of inoculation with potent septic fluid, for a month, when 

 the experiment ended. I may remark that we have in the cyanide of mercur}^ 

 a striking instance of the discordance that there may be between inhibitory 

 power and germicidal power in an antiseptic. In inhibitory power the cyanide 

 of mercury is, as we have seen, exceedingly' high ; but in germicidal power it 

 turns out to be very low. Mr. Cheyne has made experiments for me, which 

 have shown that even i-i,oooth part in water is incapable of destroying the 

 germs of bacteria. Still, the inhibitory j^iroperty of c^'anide of mercury was 

 a most important point if in other respects the salt were not disadvantageous ; 

 but, unfortunately, it proved to be so highly irritating that the greater irritating 

 property of the c^'anide of mercury more than counterbalanced its superior 

 inhibitory power. It naturally occurred to me that the cyanide of mercury 

 might perhaps combine with some other cyanide and form a double salt, having 

 advantages corresponding with those presented by sal alembroth as compared 

 with bichloride of mercury. I tried the soluble double cyanide of mercury and 

 potassium, but found it quite too irritating. I here again consulted Mr. ]\Iartin- 

 dale, and he mentioned to me that in Watts's Dictionary of Chemistry it is stated 

 that a double cyanide of mercury and zinc of very slight solubilit\' mav be 

 formed by mixing together a solution of the double c^'anide of mercurv and 

 potassium with a soluble salt of zinc, the zinc taking the place of potassium. 

 I therefore obtained some of this material, and proceeded to make experiments 

 on it. I found, in the first place, that it was quite insoluble in water. This 

 seemed at first extremely unpromising. It was soluble in about 150 parts of 

 glycerine, but insoluble in water. I found, however, that it was soluble in 

 about 3,000 parts of blood-serum, and therefore it was possible that it miglit 

 work antiseptically. I made experiments to ascertain whether such was the 

 case or not, and I found that this zinco-C3''anide of mercury, as we ma\- call it, 

 had really most important antiseptic properties ; that in the proportion of 

 i-5,oooth part it kept blood-serum perfectly free from the development of 

 organisms for eighteen days, in spite of potent septic inoculation. 



I then tried experiments with serum and blood-corpuscles as presented in 

 the whipped blood of the ox. On instituting comparative experiments between 

 sal alembroth, cyanide of mercury, and this double cyanide, I found that with 

 the alembroth all proportions lower than i-40oth ]^utrelied within twentv-four 

 hours after septic inoculation, while with tlie cyanide of mercury i-8ooth part 

 sufficed to preserve the serum and corpuscles from putrefaction. At the same 

 time, with the double cyanide I was mucli surprised antl nuich pleased to find 

 that i-i,2ooth, hah" as little again, was sullicient to keep the mixture of serum 



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