80 Mr. A. G. R Foulerton and Dr. A. M. Kellas. [Mar. 30, 



experiments carried out under the conditions more favourable to electrolytic 

 changes might have been caused by the known possible substances which 

 might be produced by the action of an electrical discharge on hydrogen 

 in the presence of water (hydrogen oxide) vapour. 



The substances which theoretically might be thus produced are ozone, 

 nascent oxygen, nascent hydrogen, and hydrogen peroxide, and we proceeded 

 to try whether we could detect either ozone or hydrogen peroxide after 

 discharging the current in an atmosphere of pure hydrogen over water, the 

 discharges being continued for periods of 15, 30, and 60 minutes. In each 

 case peroxide of hydrogen could be detected in the water after exposure to 

 the discharge, and a piece of moist starch iodide paper introduced into'the 

 tube at the termination of each time exposure gave no indication of the 

 presence of ozone. 



"We next carried out two sets of experiments in order to ascertain how far 

 the germicidal effect produced in some of the previous experiments could 

 be attributed to the action of chemical substances, of which hydrogen 

 peroxide was at any rate an important one, taken up in solution by the 

 emulsion. 



In each experiment 25 c.c. of distilled water in a test-tube were exposed 

 to the action of the discharge for 60 minutes : in the first set of experiments 

 pure hydrogen was passed through the water in order to expel any dissolved 

 oxygen or nitrogen before exposure to the discharge commenced, and was 

 then passed into the tube above the level of the water for the 60 minutes' 

 exposure ; in the second set of experiments a stream of hydrogen was passed 

 continuously through the water during the whole exposure. After exposure 

 to the discharge 5 c.c. of the treated water were titrated with sodium 

 thiosulphate and starch for the quantitative estimation of the peroxide of 

 hydrogen, the presence of which was indicated by the various tests applic- 

 able. Quantities of 5 c.c. were then pipetted off into test-tubes, and 

 inoculated respectively with two loopfuls of cultures of B. anthracis, B. coli 

 communis, and B. typhosus from agar tubes. Loopfuls of the bacterial 

 emulsion were transplanted to agar tubes at intervals of 15, 30, and 

 60 minutes, and incubated in the usual way to test the vitality of the 

 bacteria after their immersion in the solution of hydrogen peroxide. 



The results of these two sets of experiments are given in Table VII. 



