206 Davis — Electrodeless Discharge. 



The readings of the galvanometer are inversely as the damp- 

 ing or as the energy absorbed. It will be observed that the 

 absorption varies with the density of the gas subject to the 

 discharge ; also that the absorption in all gases decreases with 

 decrease of pressure. 



It was found that if the vessel V were replaced by a single 

 turn of wire whose ends were connected to a non-inductive 

 ohmic resistance, then a definite resistance could be obtained 

 that would produce the same drop-back of the galvanometer as 

 the discharge in the gas. This gives a direct method of measur- 

 ing the equivalent ohmic resistance of various gases at different 

 pressures without the presence of electrodes. 



It was my intention to determine these equivalent resistances, 

 but an accident to the apparatus compelled me to abandon the 

 experiments for that time. 



As an illustration of the great absorption of energy and 

 heating of the gas, I will mention the following experiment. 

 A vessel was constructed having a thin platinum wire pass- 

 ing downward through the center. The passage of the elec- 

 trodeless discharge heated the wire to incandescence in a few 

 seconds. 



These experiments were performed at the laboratory of Prof. 

 E. Riecke in Gottingen, to whom I wish to make acknowl- 

 edgments. for the courtesies of the Physical Institute. 



Cambridge, England. 



