Action on Bacteria of Electrical Discharges. 



61 



was impossible to appreciate what other kind of influence, if any, the 

 electrical discharge might exert. In what follows we shall refer, therefore, 

 only to the results of experiments carried out under the conditions defined 

 in (1), referring incidentally to the question of the possible influence of the 

 passage through the emulsion of rapidly oscillating currents of high potential 

 without interruption by discharge. 



The Electrical Apparatus Used. 



In some experiments the oscillatory discharge of high potential obtained 

 at the terminals of the secondary coil of the Kuhmkoff apparatus was 

 transformed by means of a spark-gap, Leyden jars, and resonating Tesla 

 coil into an oscillatory discharge of high potential and extremely rapid 

 frequency. 



In the majority of our experiments, however, the apparatus was of 

 different arrangement. The current obtained from the electric lighting main 

 was transformed into an oscillatory current of very high potential by means 

 of an alternator (connected with a transformer) which was driven by a 

 motor. Wires from the alternator were connected with the terminals of a 

 spark-gap and a large condenser immersed in oil. With this form of 

 apparatus the transformation of the current is closely analogous with that 

 occurring when the first mentioned form of apparatus is used. 



A third set of experiments were carried out with a Euhmkoff coil which 

 gave a 12-inch spark ; these last experiments being for the purpose of 

 comparing our other results with those which might be obtained by the use 

 of electrical discharges of less rapid frequency, but such as were known to 

 produce under certain circumstances distinct physiological reactions. 



In our earlier experiments the action of the discharges was tested by 

 spraying the current from a platinum wire brush on to the surface of either 

 distilled water or normal saline solution containing various bacteria. 



The emulsion of bacteria in the test-tube was exposed to the action of 

 discharges sprayed on to them through common air in one or other of the 

 following ways : — 



(a) The current was discharged from the points of a platinum brush 

 formed by a disc of platinum, 1*5 cm. in diameter, to which were attached 

 nine short lengths of platinum wire ; the disc was suspended with its surface 

 parallel to the surface of the bacterial emulsion, the ends of the wire brush 

 being between 2 and 5 cm. above the fluid. In one or two experiments a 

 different form of brush, made by twisting together some lengths of platinum 

 wire, was used, but the resulting discharge was very much less energetic than 

 when the other form of brush was used. 



