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



Table Y. 



Species. 



Duration of 

 exposure 

 to the 

 discharge. 



Current at 

 100 volts supplied 

 to motor driving 

 the alternator. 



Eeaction of the 



emulsion at 

 the end of the 

 exposure. 



Result of sub-culture 

 from the emulsion 

 after the exposure. 





mins. 



amperes. 









30 



5-8 



Neutral 



Grood growth, pigment 









formation normal 





60 



5 -8 



)j 



i> >> 





30 



5-0 



jj 



31 33 





60 



5 -0 



j) 



33 33 



In these experiments there was no appreciable change in the reaction of the 

 emulsion after exposure to the discharge ; in a set of control experiments 

 carried out with exactly the same arrangement of apparatus, but with the 

 discharge in an atmosphere of common air, the emulsion became strongly acid 

 from the formation of nitrous and nitric acids, and the bacteria were destroyed 

 at the end of the 30 minutes' exposure. 



In other experiments, in which the action of the discharge in an atmosphere 

 of hydrogen was tested, distinct germicidal effects were observed in some 

 instances. In these experiments a more energetic discharge was obtained by 

 the use of the platinum disc brush with nine points of platinum wire ; in 

 one series of experiments the current was obtained from the alternator, in one 

 other series by means of the Euhmkoff coil, and the hydrogen was passed 

 continuously through the emulsion during its exposure, with splashing of the 

 emulsion as a consequence. The results are given in Table VI, some of the 

 tests being carried out in duplicate. 



It will be seen that in a number of the experiments detailed in Table VI 

 the bacteria were destroyed ; with the current from the alternator B. typhosus 

 was destroyed after an exposure of 60 minutes, having previously survived 

 an exposure of 30 minutes, and Micrococcus agilis was destroyed after an 

 exposure of 30 minutes, whilst all the other bacteria survived. With the 

 use of the current from the Euhmkoff coil germicidal action was more 

 frequent; B. typhosus was destroyed after an exposure of 30 minutes, 

 B. dysenterice was destroyed after an exposure of 30 minutes in one instance, 

 but yielded a scanty growth in a duplicate experiment; B. coli communis 

 was destroyed after an exposure of 30 minutes in one experiment, but 

 survived an exposure of 60 minutes in another ; B. pyocyanms was destroyed 

 after an exposure of 30 minutes in duplicated experiments, and Micrococcus 

 agilis was destroyed after an exposure of 30 minutes. 



