dN 

 It 





o-N"- 



dN 

 It 



aN'- 





32 X 10' 



4 



xlO' 



28 X 



10' 



14-5 X 10-« 



88 



16 





72 





18-6 



185 



65 





120 





15-5 



297 



145 





152 





13-1 



516 



258 





258 





16-7 



Nolan and Eneight — Experiments on Large Ions in Air. 109 



early part of the curve is included, the values of i/ are no longer constant, but 

 tend to increase to a value about 40 x 10-\ This is a feature of all curves 

 obtained, and suggests that on their first entry into the tube the nuclei 

 have not steadied down to the normal and stable distribution of charge which 

 the latter part of the curve seems to indicate. 



Curve B, fig. 6, wa.s obtained when the ordinary mixture of ions and 

 uncharged nuclei as produced by the flame was exposed to the X-rays. In 

 this case there were present 22-6 x 10' uncharged nuclei per c.c, as before, 

 and, in addition, 16 x 10' ions, making 38-6 x 10' nuclei per c.c. in all. 

 The following table shows five determinations of rj made from curve B. 



N 



50 X 10' 

 100 

 200 

 300 

 400 



The values of j; are on the average about 50 per cent, higher than those 

 found previously, and they are not nearly so constant. In this case also the 

 value of 1), if calculated from the first part of the decay curve, comes out very 

 high, the value of the maximum reading being about the same as that found 

 in the other case, i.e. 40 x 10"^. 



It is not quite clear why the two methods should yield results differing 



by 50 per cent. It must not be forgotten, however, that we are treating in 



a very simple form a process which is no doubt very complex. We have 



many kinds of ion in addition to the uncharged nuclei. These are present 



in unknown proportions ; each has its characteristic combination coefficient 



with small ions of one sign and the other. It is possible that in the second 



experiment a greater proportion of the nuclei were charged during the 



time when the recombination was under observation, and that the effect 



of this on the whole was a more rapid disappearance of the small ions. 



We could probably, without serious error, fix the recombination coefficient 



between small ions and nuclei between the limits 5 and 20 x 10"S the lower 



value being characteristic of the uncharged nuclei and the higher values of 



the ions with various charges. In the case of large ions occurring naturally, 



narrower limits could be fixed, as highly charged ions are unlikely. As far 



as phenomena of the atmosphere are concerned, the recombination coefficient 



probably lies between 5 and 10 x 10"", and probably closer to the lower than 



to the higher figure. 



E.I. A. PEOC, VOL. XXXVI, SECT. A. [11] 



