Ionization from Heated Platinum. 177 



electronegative elements iodine, bromine, fluorine, it has 

 been shown by Richardson * and by Sheard f that the 

 negative constituent consists of negative ions or an admix- 

 ture of negative ions and electrons. The following theory, 

 based upon experimental evidence of a general character 

 and upon the specific results outlined in the preceding para- 

 graphs, will, I believe, account for these phenomena. Let 

 us assume a molecule consisting of two atoms, A positively 

 and B negatively charged. When the temperature is raised 

 decomposition of the molecule occurs i, and under the in- 

 fluence of an applied electric potential the positively charged 

 atom A is expelled, for example, and the atom B, negatively 

 charged, is retained. At the still higher temperatures at 

 which the negative atom begins to discharge electrons, the 

 atom B loses a corpuscle. If the negative atom B is driven 

 off* before losing corpuscle?, as occurs in the case of some 

 halogen compounds, we should get an emission of negative 

 ions. If, however, the atom B loses an electron and this is 

 then discharged, B will be left without charge, and hence 

 will not normally recombine with the positive atom A. This 

 would explain the increased positive emission produced at 

 low temperatures by heating a wire under such conditions 

 as to give off negative electricity. 



If the temperature is raised without the expulsion of ions 

 or electrons, then at low temperatures dissociation occurs 

 giving -fAand — B. Some recombination doubtless occurs; 

 in the main, however, the net result would be to build up 

 positive material A to be later emitted as positive ions 

 under an applied electric force. At still higher temperature 

 B loses an electron ; this may find its Avay to the positively 

 electrified atom A, neutralizing its charge, so that A and B 

 are both without charge. Atom A, now having no charge 

 and being the electro-positive element, can more readily lose 



* Phil. Mag. Sept. 1913, pp. 452-472. 



t Phil. Mag. March 1913, pp. 370-389. 



^ The wire was heated electrically ; there was a drop of potential 

 across the wire varying from 0*75 to 1*2 volts within the range of 

 temperatures used in these experiments. The theory of electrolysis 

 is applicable, with some modifications, to liquids, gases, and solids ; in 

 the case of solids, however, there is no migration of the ions formed; 

 the potential difference across the wire in the heating circuit operates, 

 however, as an agent in accelerating molecular dissociation and in 

 preventing recombination. There is no reason to believe that the 

 r°sults given in this paper could not bo obtained by a non-electrical 

 method of heating; there would probably be a diminution in the 

 magnitude of the effects at any given temperature, however. In this 

 connexion the recent work of Harker and Kaye (Proc. Roy. Soc, A. 

 vol. lxxxvi. pp. 379-396 ; et al.) is of interest. 



Phil. Mag. S. 6. Vol. 28. No. 164. Aug. 1914. N 



