390 Mr. A. S. Eve on 



Recombination of Ions. 



In order to form an estimate o£ the rate of recombination 

 of the ions, various lengths of glass tubing, 6 mms. in diameter, 

 were inserted between the sprayer and the electroscope. 

 The results obtained for positive ions from water spray were, 

 to an arbitrary standard, as follows : — 



Length of Tubing. 



Ionization value 



0*85 metres 



100 



3-62 



92 



6*78 



79 



9-90 



60 



13-00 



49 



Thus half the ions disappeared during the three seconds 

 in which the air-current traversed the 12 metres of tubing. 



With tubes of this small diameter, 0*6 cm., many of the 

 ions must vanish, not by recombination but by contact with 

 the sides. The thin tubes were replaced by 3 metres of 

 glass tubing, 2 ems. in diameter. The loss due to traversing 

 this volume was 50 per cent., so that half the ions disappeared 

 in eight seconds. When the spray was introduced for one 

 minute the losses of potential during successive minutes,, 

 including the first, were 



47 — 9 — *9, without the 3 m. of tubing, 

 and 19 — 8 — '8, with the 3 m. of tubing. 



The loss in the tube, therefore, occurs among the more 

 mobile ions, since the catch during the second minute is the 

 same in both cases. 



As the ions of benzyl alcohol were the slowest compared 

 with those from all the liquids tried, I have made some ex- 

 periments to find out how long these ions may be stored 

 without disappearing by recombination or by diffusion to the 

 sides of the containing vessels. For example, Griese found 

 that the gases from flames could be stored for six or seven 

 minutes and still retain their conducting properties. 



If the spray from benzyl alcohol was passed into the elec- 

 troscope for a quarter of a minute, we have already seen 

 that the ions, whether positive or negative, move in a most 

 leisurely manner, and are not extracted until about ten 

 minutes have elapsed. If the air and spray traversed 3 metres 

 of glass tubing, 2 cms. in diameter, there was a loss of 30 per 

 cent, of ions ; corresponding to a loss of 50 per cent, for the 

 ions from water spray, as Stated above. This proves that 

 the ions of benzyl alcohol are slower to recombine than those 



