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Ihe Germicidal Action of Metals and its Relation to the 

 Production of Peroxide of Hydrogen. 



By Allan C. Eankin, M.D., Demonstrator in Bacteriology, McGill 

 University, and Assistant in Bacteriology, Eoyal Victoria Hospital, 

 Montreal. 



(Communicated by J. G. Adami, F.R.S. Eeceived June 12, — Read June 24, 1909.) 



(From the Pathological Laboratory, Royal Victoria Hospital.) 



That sundry metals possess not merely a distinct inhibitory action upon 

 the growth of moulds, bacteria, and other micro-organisms, but even possess 

 germicidal properties has been known for a long period, and there have been 

 numerous observations demonstrating this action. The earliest observation 

 known to us is that by Kaulin in the seventies, upon the remarkable 

 inhibition produced by traces of silver upon the growth of the As2)er(jillus 

 niger. More recent work has in general followed the lines of the experiment 

 employed by Miller, in his observations upon the bactericidal properties of 

 gold and various alloys employed in dentistry ; namely, plate cultures have 

 been made of various micro-organisms, and into the inoculated culture media, 

 while still fluid, small pieces or plates of the metals have been dropped, the 

 presence or absence of a clear surrounding zone indicating arrest of growth 

 of inoculated bacteria. As a result of these observations, it has been shown 

 that certain metals pDSsess inhibitory powers. More than this, according to 

 Behring, reinoculation of the clear zone after the removal of the metal may 

 lead to continued negative results. This would indicate that not merely is 

 there inhibition, but an alteration of the gelatin, and suggests strongly the 

 presence there of substances having a distinct germicidal effect. A full study 

 of this nature was made by Bolton. Other observations (Ficker, Von der 

 Deis, Clarke and Gage) have been along the lines of either employing 

 metal vessels to hold the inoculated fluids, or placing strips of the metal in 

 "lass vessels holdin<i water containing known cultures of bacteria. In these 

 experiments also, metals like copper, zinc, and silver have been noted to 

 possess distinct bactericidal eflfects. I5ut in tlie altove observations tliere 

 has been no adequate attempt to determine the means whereby the metals 

 exert their bactericidal action. Leedham-Green, however, made the observa- 

 tion that iron was inert or active according as to whether the conditions of 

 the experiment prevented or ])crmitted free oxidation of the metal. It was 

 tlirough oxidation that inhibitory action was brouglit aliout. 1'lie general 

 opinion lias been that there is a diffuHion of the metal into the water or 



