72 Mr. A. G. B. Foulerton and Dr. A. M. Kellas. [Mar. 30, 



emulsion with the acid solution, and subcultures were made after the 

 organism had been exposed to the action of the acid solution for periods 

 of 15, 30, and 60 minutes. The inoculated tubes were then incubated for 

 96 hours at an appropriate temperature, and the amount of growth, if any, 

 compared with that obtained from similar subcultures made from similar 

 emulsions in distilled water. 



The results of these experiments are given on Table III : — 



Table III. 













Eesult of 











Percentage 



exposure 



of 









Acidity 



bacteria to acid 





Duration of 

 the exposure 

 of water 



to the 

 discharge. 



Current at 



(calculated 



of acid in 



solution for times 





100 volts 



as nitric acid 



emulsion 



as below. 



Species. 



supplied to 

 the motor 



per cubic 

 centimetre) 



after 

 experiment 



+ = growth 



obtained. 





driving the 



of solution 



(calculated 



= no growth. 





alternator. 



at end of 



as nitric * 















experiment. 



acid). 



15 

 mins. 



30 

 mins. 



60 

 mins. 



Series 1. 





amperes. 















mins. 















30 



6 



0-0022 



0-22 







' .0 







_B. coli communis .. 



30 



6 



0-0028 



-28 















B. prodigiosus . . . 



30 



6 



-0033 



0-33 















Series 2. 



















15 



, 6 



0-001 



o-i 



+ 



+ 







15 



6 



0-0007 



0-07 













J3. coli communis .. 



15 



6 



0-0011 



0-11 















15 



6 



0-0008 



0-08 













£. pyocyaneus ... 



15 



6 



-0013 



0-13 













B. prodigiosus . . . 



15 



6 



-00097 



-097 













From the results shown in Table III it will be seen that, except as regards 

 the tube in which a sporing culture of B. anthracisw&s treated, the substances 

 taken up from the air by water exposed to the action of the discharge were 

 sufficient to destroy the bacteria subsequently immersed in the acid solution 

 for so short a period as 15 minutes. It will be seen also that, although the 

 tubes used in each series of experiments were exposed to the action of the 

 discharge under conditions as nearly equal as the apparatus and current at 

 our disposal would allow, there was considerable variation in the resulting 

 degree of acidity, as had occurred also in the experiments detailed in 

 Tables I and II. In short, it soon became obvious that we were utilising 

 forces which were not under nice control, and that our results must be taken 

 as being comparative in only an approximate degree. 



