﻿142 Mr. Clinton J. Davisson : Role Flayed by Gases 



electrical emission was, in all tbese cases, accompanied by the 

 emission of carbon monoxide or carbon dioxide, the gas 

 molecules did not carry the current. 



One other point was tested before running the blank 

 experiment mentioned above. It was thought desirable to 

 determine if any quantitative relation existed between the 

 electrical and gas emissions. The results or! two experiments 

 with this end in view are tabulated below. In Table I. the 

 temperature of the strip was adjusted to about 1000° C. at 

 three o'clock. The subsequent observations show that al- 

 though the gas pressure had reached an equilibrium in fifteen 

 minutes the electrical emission was still increasing at the end 

 of forty minutes. 



Table I. 



Til 



3 GO 

 3 15 

 3 22 

 3 30 

 3 40 



Thermionic 

 Current in 

 Amperes. 



8-4x10" 

 12-0x10' 

 24-0x10" 

 48-0x10" 



Eqnilibrium 

 Pressure in 

 mm. of Hsr. 



.-)X10~' 

 129X10 - ' 3 

 122X10 - * 5 



129x10" 



129X10' 



The experiment was necessarily discontinued at this point. 

 The heating current was reduced to zero, but the pumping 

 continued. Five hours later the temperature of the strip was 

 again adjusted to about 1000° C. and observations continued 

 over a period of twenty-four hours. These observations, 

 which appear in Table II., are strongly in support of the view 

 that the two emissions are entirely independent. Similar 

 results were obtained by Richardson * in an investigation of 

 the relation between gas emission and the emission of positive 

 thermions from platinum. A determination of ejm made 

 after 10 00 a.m. (see Table II.) gave the value 100, which 

 compares favourably with one-half the electrolvtic value for 

 strontium, 111. 



Experiments similar to these have also been made upon a 

 sample of strontium sulphate with essentially the same 

 results. A slight increase in the gas pressure was noted 

 when the strip was heated to about 600° 0. A determination 

 of ejm at this temperature indicated potassium, the value 

 * Congres de liacliolofrie. Cnmptr-s Rcndus, Brussels, 190o. 



