56 



Dr. A. Kansome and Mr. A. G. E. Foulerton. 



We determined, therefore, to investigate this question anew, in the 

 hope of being able to come to a definite conclusion. The matter 

 seemed to us to be one of considerable importance, since if ozone were 

 possessed of the bactericidal properties which have been attributed to 

 it by more than one investigator, the gas might prove of much value 

 in solving one of the most unsatisfactory problems which have to be 

 dealt with in the practice of modern sanitation, that is to say, the 

 disinfection of rooms after the occurrence of infectious disease. Ozone 

 can now be conveniently produced in large quantities, and, if efficient, 

 would be admirably adapted to effect the purpose in view. 



The question of the bactericidal action of ozone was especially brought 

 into prominence by the classical work of Downes and Blunt, embodied 

 in communications made to this Society in 1877 and 1878.* Working 

 with impure cultures of bacteria, these investigators showed that direct 

 sunlight in the presence of atmospheric air was capable in some cases of 

 preventing in greater or less degree, or in other cases of absolutely 

 inhibiting, the growth of the particular bacteria experimented with ; and 

 that not only might growth be inhibited, but that the bacteria them- 

 selves might be actually destroyed. Downes and Blunt further 

 showed that so far as the destruction of bacteria is concerned the 

 blue and violet rays of the spectrum are more effective than the red 

 rays, that the interposition of a layer of water is sufficient to protect 

 the bacteria to a certain extent, and that direct sunlight acting in 

 vacuo may fail to destroy sporing bacteria. 



Whilst this work of Downes and Blunt has been fully confirmed and 

 amplified in certain directions by the work of others, no satisfactory 

 explanation has yet been arrived at as to exactly how it is that bacteria 

 are destroyed under these conditions. The explanation that the 

 result is a direct effect of the sun's rays — of heat — has been shown to 

 be untenable ; and it has therefore been assumed that the destruction 

 is effected by chemical rather than by physical action ; that it results from 

 an active oxidation of the substance of the bacteria by ozone, produced 

 by the action of sunlight on atmospheric air. Others have regarded 

 peroxide of hydrogen as the active agent. 



Amongst the experiments which have been carried out in order to 

 test this assumed bactericidal action of ozone, we may particularly 

 mention those of Chapuis,f Sonntagj, and Ohlmiiller.§ Chapuis filtered 

 air through cotton wool, and then exposed plugs of the wool with 

 the contained bacteria to the action of ozone. The plugs were after- 

 wards incubated in a nutrient wort solution, which remained sterile. 

 Control plugs of the wool which had not been subjected to the action 



* < Boy. Soc. Proc.,' toI. 26, p. 488 ; vol. 28, p. 199 ; rol. 40, p. 14. 



f * Bulletin de la Societe Chimique,' 1881, Tome 35, p. 290. 



X * Centralblatt fur Bakteriologie.' Erste Abteilung, Band 8, p. 778, 1890. 



§ ' Arbeiten a. d. Kaiserl. Gesundheitsamte,' 1892, Band 8, p. 229. 



