ELECTRIFICATION OF AIR, VAPOUR OF WATER, AND OTHER GASES. 199 

 The following results were obtained from 120 strokes of the pump : 



35. The lower half of the funnel was now removed and the upper half used. The 

 water now fell clear through the whole length of the funnel, and the extracted air 

 gave, by 120 strokes of the pump as usual, ^ to g volt negative. No electrification 

 in the extracted air could be detected if no water was falling. 



36. Putting the water-dropper ( 33) in the top of the shortened funnel and 

 allowing a strong solution of salt water to fall down from the dropper, volt positive 

 was got from the extracted air. Placing pure water in the dropper and testing 

 again, volt negative was found. 



ELECTRIFICATION OF AIR BY AN INSULATED WATER- DROPPER AT 

 DIFFERENT POTENTIALS ( 37). 



37. The water-dropper was now insulated and connected with the positive 

 terminal of 1 or more, up to 12, cells of a secondary battery, the negative 

 terminal of which was connected with the funnel, and vice versa. On letting water 

 fall from the dropper, and testing the electrification of the air in the funnel by 

 drawing it through a testing filter, the results were not sensibly affected by 

 substituting metallic connections for the connection of the battery terminals with the 

 dropper and funnel. Hence, the large positive and negative electrifications thus 

 given to the drops as they fell from the nozzle did not sensibly diminish or increase 

 the negative electrification which they produced in the air through which they fell. 



EFFECT OF HEAT ON ELECTRIFIED AND NON-ELECTRIFIED AIR ( 38, 39). 



38. The apparatus shown in fig. 5 was designed and used for the purpose of 

 trying to diselectrify.air by heat. Air is admitted into a tin plate biscuit canister, B, 

 near the bottom. Two metallic tubes are fixed into it at the middle opposite each 

 other. One of these two is plugged with paraffin through which passes a wire, 



