THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



<Vbra>v 



[SIXTH SERI 



MARCH 191 



XXI. On the Positive Ionization from Certain Hot Salts, 

 together with some Observations on the Electrical Pro- 

 perties of Molybdenite at High Temperatures. By A. T. 

 "Waterman, Princeton University *. 



THE general problem as to the character of the ionization 

 from hot bodies has been examined in considerable 

 detail during recent years. The results obtained from ex- 

 periments with metallic strips indicate, on the whole, no 

 characteristic emission, but one which is apparently the same 

 for all the metals and due no doubt, so far as the positive 

 emission is concerned, to some common impurity. The 

 positive emission is now generally considered to consist 

 mainly of potassium atoms with a single charge ; the nega- 

 tive of electrons. 



From experiments with various salts the following general 

 conclusions have been reached, although there are excep- 

 tions : — 



I. Positive emission : characteristic of the metallic con- 

 stituent. 

 II. Negative emission : electrons accompanied in some 

 cases by an emission characteristic of the remaining 

 constituent. 

 The metals whose salts (chiefly the halides and sulphates) 

 have been investigated are : — 



Alkaline group : K, Na, Li, Rb, Gs. 

 Alkaline-earth group : Be, Mg, Cd, Zn, Sr, Ca, Ba ; 

 and Al, Mn, Fe. 



* Communicated by Prof. 0. W. Richardson, F.R.S. 

 Phil. Mag. S. 6. Vol. 33. No. 195. March 1917. Q 



