Heat produced by Emission of Ions from Hot Bodies. 643 



points to the left o£ the diagram, which are a long way from 

 the line. They correspond to the measurements with small 

 thermionic currents, and are necessarily subject to a large 

 error. In some cases also these currents were not saturated, 

 which may introduce systematic errors. The increase re- 

 ferred to is larger than the R# term would cause. Moreover, 

 the small systematic error which occurs with large values of 

 T, and which at present we are not able to calculate ac- 

 curately, tends to make the measured value of cf> too small 

 when T is large. It will therefore tend to off-set the effect 

 of the B.0 term. Thus there seems to be a small but definite 

 increase of <f> with 6. 



The discussion of this question will not be pursued further 

 at present. In fact there are a number of points connected 

 with the theory of these effects which we shall be able to deal 

 with more satisfactorily when data relating to the thermionic 

 emission from osmium at different temperatures are available. 

 We expect to have these data at our disposal very soon. We 

 wish to point out, however, that the above experiments afford 

 a strong confirmation of the views about the nature of the 

 emission of electrons from hot bodies which have been put 

 forward by one of the authors. In particular, since osmium 

 is closely related to platinum both chemically and physically, 

 one would expect it to have a very similar value of (£. The 

 above value is very close to the value of the corresponding 

 quantity which we obtained from the converse heating effect 

 when electrons were absorbed by platinum, and is not very 

 different from the values of the latent heat, expressed in 

 equivalent volts, which one of the writers and others have 

 deduced from the temperature variation of the emission of 

 electrons by platinum. 



We are glad to be able to take this opportunity of thanking 

 Mr. A. A. Barnes, who assisted us with the preliminary 

 experiments and made several valuable suggestions, and Mr. 

 Cornells Bol, who took most of the observations. 



Palmer Laboratory, 

 Princeton, N. J. 



2X2 



