

44 



EXPERIMENTS WITH IONIZED AIR. 



— {d V/dt)/ Vov — {dQ/<Jt)/Q, where Q is the charge of the one condenser plate, the 

 other being kept at zero. The justification of this t'({uation is at hand: Let n be 

 the number of ions available,^ the average charge of each, ^^their relativ • veh)city, 

 X the distance apart of the condenser plates of area A, for the potential difference 

 V. Then —{dQ/dt)= U ( V/x)ne=—G (d V/dt), where C is the cajiacity of the 

 condensers conjointly, (ilQ/dt) being the ciii-i-ent, all taken per square cm. Hence, 

 if for brevity A/cx=^\, — (dV/dt)/ V=: JJne^c. It will be convenient to express 

 the data in terms of common logarithms, wherefore c'= — logf (^1 V/dt)/ V will be 

 given and V=^ F^IO""'', and c'= Unelogj^^cloge. 



4. Data as to ageing of tlie ionizer. — The first question at issue, is the behavior 

 of phosphorus itself, the object being to throw light on its persistence as an ionizing 

 agent in the lapse of time, change of temperature, etc. The following tables show 

 results. The leakage of the condenser was observed in the lapse of time, the 

 appaiatus being charged at successive intervals but not otherwise interfered with. 

 The constant c' (varying with n the number of ions per cubic centim.) was 

 found for each two minutes after charging. Plate distances of 1 and 3 centims. 

 occur in the tables. 



TABLK 



-DECAY OF IONIZING ACTIVITY OF PHOSPHORUS. 



