Electrification of the Atmosphere. ±h} 



Deviation of Electro- 

 Electrified Air from Iron Tube was drawn throngh. meter in volts per 



Stroke of Pump. 



I. R. Tube only 



(i.) I.R. Tube + U tube with Pumice and H2SO4 



(ii). I.R. Tube + water 



(iii.) I. R. Tube + water + KI solution 



(iv.) I.R. Tube + 'Pvro' + U. tube 



(v.) I. R. Tube + water + KI + Pvro 



+0-070 

 -j-0'o6o 

 -i-0050 

 +0-045 

 +0016 

 +0020 



(vi.) I. R. Tube + water + KI + Pvro + U Tube +0-000 



From this we might infer that the electrification is not carried 

 to any extent by solid particles, by water vapour, or by ozone, but it 

 would seem to be carried by the oxygen chiefly. 



In the case of the copper tube at a red heat, the effect produced, 

 as the air was passed through, was a positive electrification of the 

 air. After the tube was oxidized coal gas was passed through, which 

 when tested by the filter showed a large negative electrification. The 

 positive and the negative electrifications were observed even with 

 the .whole apparatus to case, a change in the sign of the electrifi- 

 cation of the copper tube relative to the insulated axial wire 

 did not produce a change in the electrification of the air or of the 

 coal gas. 



In the experiments with phosphorus, a clean stick of that 

 element about six inches long was placed in a small zinc trough. 

 Water was then poured into the trough so as to leave exposed only 

 the upper side of the stick of phosphorus. The zinc vessel was 

 then placed inside a zinc tube. When the whole was connected to 

 case and air was drawn off to the filter — precautions being taken 

 to ensure that the air drawn to the filter passed first over the 

 phosphorus — it was found that little or no electrification was shown 

 on the filter. On the other hand, when the zinc tube with which 

 the zinc vessel containing the phosphorus was in metallic contact 

 was connected to one terminal of a batten- of Leclanche cells and to 

 the case of the instrument, while the insulated axial wire was con- 

 nected to the other terminal of the batter}', the air was found to be 

 positively or negatively electrified according as the insulated wire 

 was negatively or positively electrified. The electrification due to 

 the oxidation of phosphorus shows in this respect a marked differ- 

 ence from that due to oxidation caused by heating. 



The fact that clean iron and clean copper, when oxidizing,, 

 electrify the surrounding air positively was experimentally verified by 

 Schuster. The effect due to phosphorus has been studied very 

 thoroughly by Elster and Geitel. These known results are given here 

 simply to indicate the capability of the present arrangement wherein 

 an electric filter is used. 



