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



efficient means were adopted for keeping the temperature of the emulsion 

 below the point at which the germicidal effect of heat would come into play, 

 and when there was no great amount of "sparking" from the wire to the 

 platinum disc, the mere passage of the current through the emulsion for 

 periods of time corresponding to those prevailing in the previous experiments 

 had no obvious effect on the bacteria. In certain experiments of this kind, in 

 which the bacteria were destroyed, tbe emulsion was found to contain at the 

 end of the experiment definite quantities of chemical germicidal substances 

 which had been formed by excessive sparking just above the level of the 

 emulsion from the wire which was connected with the immersed platinum 

 disc. 



If special precautions for keeping the emulsion cool were not taken, the 

 heating effect of the passage of the current through the emulsion was very 

 marked in these experiments with the immersed disc, the temperature rising 

 rapidly to 55° C. or higher. 



The following experiments with somewhat prolonged passage of the current 

 through the emulsion may be specially referred to. The current was applied 

 in each experiment for six successive periods of 10 minutes each, with 

 intervals of five minutes between, and the tube containing the emulsion was 

 kept surrounded by melting ice. Under these conditions the temperature of 

 the emulsion never rose above 32° C, a degree of heat which, for the time 

 duration of the experiments, would not have any injurious effect upon either 

 of the species tested. 



Experiment 1. — A thick, deep red emulsion of B. prodigiostts in distilled 

 water was exposed to the action of the current. A certain amount of sparking 

 occurred just above the surface of the emulsion from the wire which was 

 connected with the terminal platinum disc. The red colour of the emulsion 

 was quickly discharged, and the bacteria were all killed at the end of the 

 experiment. The emulsion had become strongly acid, 1 c.c. of it containing 

 - l c.c. of N/40 acid, equivalent to - 016 per cent, of nitric acid. 



In a control experiment, carried out without immersion of the tube in 

 melting ice, the temperature of the emulsion had risen to 65° C. at the end of 

 the 60 minutes' exposure. 



Experiment 2. — The organism tested was B. pyocyaneus in an emulsion with 

 normal saline solution, and a constant stream of hydrogen was passed through 

 the fluid. In this instance, again, the bacteria were all destroyed at the end 

 of the experiment, and the emulsion was found to contain in solution some: 

 substance which was capable of liberating iodine from iodide of potassium. 



Experiment 3. — An emulsion of B. pyocyaneus with normal saline solution 

 was again used ; hydrogen was passed through the tube above the level of the- 



