Electrification of the Atmosphere. 



149 



§5. Questions for expeirmental investigation. 



Experiments were made to test (a) \Yhether the nature of the 

 electrification, positive or negative, given to the air could be deter- 

 mined by the nature of the charge given to the surrounding vessel 

 i.e. how the electrification of the gas was influenced by the 

 electromotive force ; (b) what it was that carried the electrification ; 

 (c) whether the electrification of the gas was destroyed by passing a 

 current throught it, when electrified ; (d) whether it was possible to 

 transmit the agency effective in causing the electrification from one 

 space to another by means of drawing the electrified air from one 

 space to another. 



§6. The effect of the electromotive force on the electrification 

 of the gas. 



In the various experiments the zinc alone was first tested, the 

 temperature being such as to cause oxidation but not fusion of the 

 zinc. It w^as found that in such circumstances the air was not 

 electrified. Potassium bichromate was first placed on a strip of 

 zinc, 22'5 cm. by 2 cm., and sprinkled with iodine, and in some 

 cases the whole was placed in the zinc tube, but in later experi- 

 ments the zinc strip and its covering of potassium bichromate and 

 iodine were heated so as to drive off the iodine, and then the 

 strip was placed in the zinc tube and heated. In cases where 

 bromine was used the bromine was sprinkled over the potassium 

 bichromate on the zinc strip, and allowed to evaporate, and then 

 the whole was placed in the zinc tube and heated. The air drawn 

 through the tube and tested by the filter (Fe) was strongly electrified 

 positively even with ever}'thing to case. The electrification was 

 positive both when the insulated axial wire was joined to the positive 

 and when it was joined to the negative terminal of the Leclanche 

 battery, the other terminal being joined to the zinc tube and the 

 case of the instrument. The results are exhibited in the following 

 tables : — 



POTASSIUM BICHROMATE AND BROMINE ON A ZINC 

 STRIP IN ZINC TUBE. 



Axial Wire. 



Case 



+ 3 volts 

 + 12 volts 

 +36 volts 



Deviation in Volls 



per Stroke of 



Pump. 



+0-054 

 +0'05o 

 -f-o-o63 



-I-0-07C 



