Induced-Radioactivity in Air. 361 



conductivity given to the gas by passing through the liquid 

 in the sprayer; by changing this liquid the effect of the 

 nature of the liquid on the conductivity communicated to a 

 gas passing through it could easily be determined. 



The following is an example of some experiments o£ this 

 kind : — 



Vessel B, normal saturation-current be- 

 fore spraying wire + 16, wire — 16 



Pure distilled water in the sprayer, the 

 air after passing through the sprayer 

 went into B, duration of experiment 

 15 minutes, saturation-current . . wire + 33, wire — 30 



Air blown out of B, saturation-current . wire + 15, wire — 15 



Strong solution of ]NaCl in the sprayer, 

 air passed through sprayer as before 

 for 15 minutes, saturation-current . wire + 30, wire — 28 



Thus there is no clearly-marked difference between the effects 

 o£ pure water and brine. Solutions of rosaniline, phenol, 

 hydrogen peroxide, and sulphuric acid were tried, and all 

 gave much the same effects as pure water : the amount of 

 electrification given to the air by bubbling through these 

 solutions is very different, so that these experiments afford 

 another proof of the difference between the conductivity 

 communicated to a gas and the amount of electric charge. 

 Another illustration of this is that though when air is first 

 bubbled through distilled water it is strongly negatively 

 electrified, it loses its charge much more rapidly than its 

 conductivity, and after the lapse of an hour or so the charge 

 will be unappreciable while the conductivity will be almost 

 as large as it was at first. 



Ether, alcohol, and turpentine were placed in the sprayer 

 and air forced through them, but with these liquids no 

 appreciable conductivity was produced. 



When coal-gas was forced through distilled water in the 

 sprayer the conductivity was much less than when the same 

 volume of air was passed through. 



Induced Radio- Activity produced on a JSegatively-Electrijied 

 Surface immersed in Modified Gas. 



The experiments already described have shown that when 

 air is in its normal state the volume o£air in the closed vessel 

 A is too small to give the induced radio-activity observed in a 

 negatively electrified wire placed in the open air. We have 

 seen too that when the current of electricity through the 

 vessel is increased by exposing the gas in it to Rontgen rays, 



Phil. Mag. S. 6. Vol. 4. No. 21. Sept. 1902. 2 B 



