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



The emulsion was then subjected to the action of the discharge for the 

 required time, at the end of which two agar tubes were each inoculated with 

 a loopful of the treated emulsion. All the agar tubes were then incubated 

 side by side at a temperature suitable to the growth of the particular 

 organism under experiment, and any differences in growth on the experimental 

 and control tubes were noted from time to time. At the conclusion of an 

 experiment any necessary chemical examination of the emulsion was made 

 immediately after the agar tubes had been inoculated.. 



II. — The Germicidal Action of the Discharge when Sprayed through 

 an Atmosphere of Common Air. 



Preliminary experiments, in which the bacterial emulsions contained in 

 tubes of the type described under (a) were exposed to the action of the 

 discharge of oscillatory currents of high potential and rapid frequency, 

 sprayed on to the surface of the fluid through an atmosphere of common 

 air, resulted in rapid destruction of the organisms. And we found that the 

 discharge of the current on the surface of the emulsion was followed by the 

 development of a considerable degree of acidity in the fluid, due chiefly, at 

 any rate, to the presence of nitrous and nitric acids in solution. 



Tables I and II give the results obtained in two sets of such experiments, 

 in all of which precaution was taken to keep the bacterial emulsion at 

 a temperature which could not by itself possibly affect the bacteria 

 unfavourably, being below 30° C. in every case. 



In the experiments detailed in Table I the current was transformed from 

 the electric lighting main ; the experiments of Table II were carried out with 

 a powerful induction coil which gave a 12-inch spark, and the platinum brush 

 was connected up with one terminal of the secondary coil, whilst the other 

 terminal was connected with the layer of mercury at the bottom of the 

 beaker in which the tube containing the bacterial emulsion was suspended. 

 In every case, except in the experiments of Series 4 and 5 of Table II, the 

 ends of the platinum brush were 2"5 cm. above the surface of the emulsion. 



From the results given it will be seen that, except for the two sporing 

 species, B. anthracis and B. megaterium, the bacteria tested were destroyed 

 after comparatively short exposure to the discharge, when the ends of the 

 brush were suspended at a distance of 2 - 5 cm. above the surface of the fluid, 

 whilst in the few experiments included in Series 4 and 5 of Table II, when 

 the brush was suspended 5 cm. above the surface of the fluid, a non-sporing 

 organism, B. coli communis, escaped complete destruction, although some 

 inhibition of subsequent growth was observed. In experiments with 

 B. anthracis our results were not quite consistent; in the experiment of 



