Kennedy — Large Ions and Condensation- Nuclei from Flames. 65 



There are many difficulties iu understanding the origin of the large ion or 

 nucleus, but Langevin' and Sir J. J. Thomson* have given a satisfactory theory 

 of the nucleus in its final stat-e as consisting of a minute water-drop retaining 

 a stable size in unsaturated air, the size being almost independent of the 

 charge carried. When two such nuclei come into collision and coalesce, the 

 two will form one tiny drop with a radius greater than the equilibrium value, 

 and evaporation will take place uutH equilibrium is restored, so that the 

 new nucleus will have the same sise and properties as either of the 

 original ones. On such a theory it is to be expected that the frequency 

 of the collisions, and consequently the rate of disappearance of the nuclei, 

 should be proportional at any time to the square of the number present. 



Fig. 7 is the graph of — with the time, and shows that 



and 



1 



n 



1 



«0 



= 7^ 



dn 



dt 





yn-, 



i\ being the initial value, and 7 a constant. 



'JO 80 



Minutes 

 Fis. 7. 



12c 



Experiment therefore supports the idea of 

 the disappearance of the nuclei being due to 

 collision and'consequent coalescence. 



It next seemed of interest to ascertain 

 what effect the electric charge has on the col- 

 lision frequency and rate of disappearance of 

 the nuclei, and for this purpose similar ex- 

 periments were made when the gasometer 

 was filled with flame-gas without ha%'ing re- 

 moved the ions. In this ease some of the 

 nuclei are charged positively, an equal number 

 negatively, and the remainder uncharged. The 

 uncharged nuclei \s'ere in such experiments 

 about half or one-third of the total number. 



Table III shows the result of such an 

 experiment. 



IE. Block: "Ann. de Physique et de Chimie," 1905; Chauveau : "Le Radium," 

 Avril, 1912. 



- Conduction of Electricity through Gases. 



li.I.A. PBOC, VOL. XXSIII., SECT. A. [10] 



