Ionization from Heated Platinum 

 Table I. 



175 



Applied potential = +200 volts. Wire at zero potential 

 during heating. 



Curve 1(0). Initial positive current readings obtained at 628° C. after 

 heating- in air at various temperatures. 



Curve II (©). Slow decay currents, following Curve I. 



Curve III (O). Initial current readings, as per method for Curve I., 



after first heating in Bunsen flame. 

 Curve IV ( A ). Steady current values following Curve III. 

 Curve V ( + ). Initial current readings after second heating in Bunsen 



flame. 





Minutes 

 heating 

 at V=0. 



Air. 



Bunsen Flame I. 



Bunsen 



Temp. c O. 



Initial 



Steady. 



Initial Steady 



Flame II. 



(Curve I.). 



! value 



(Curve III.). 



value 



Initial 







(Curve 11.). 





(Curve IV.). 



(Curve V.). 



628 



Fixed Point. 



14 



! " 



24 





31 



644 



8 



50-2 



13-5 









654 



10 



1105 



23-2 



47 



... 





666 



10 



410 



110 









690 



11 



331 



220 



38 



14-4 



12 



714 



10 



45-2 



223 



40 



38 





738 



10 



132 



8 



58 



38-6 



40 



750 



10 



221 



8 



82 







765 



10 



200-6 



6 



89 



112 



8-3 



774 



10 



101 



41 









786 







... 



*7-l 



*3-8 



"i-6 



798 



i'd 



26 



1-4 









822 



10 



17-5 



0-85 









840 



10 



10-3 



0-63 



1 









obtainable at higher temperatures (700° C. on) decreased 

 steadily with continued usage of the wire, and exhibited no 

 such effects as have just been described. These facts point 

 to the existence of a substance capable of producing ions 

 when heated at relatively low temperatures and that this 

 substance, when the wire is left cold, builds up ionizable 

 material with time as if it were radioactive. Sir J. J. Thom- 

 son comments on the possibility of such a substance in his 

 ' Conduction of Electricity through Gases,' page 214. 



Referring again to Curve I., fig. 1, it will be seen that 

 the positive thermionic current, tested at the fiducial 628° C. 

 point, reached an extrapolated maximum value of about 

 260 div. per sec. when previously heated at 756° C. Heating 

 the wire at still higher temperatures gave currents, at 628° C, 

 falling off in value rapidly from 756° C. to 820° C. 



