1895.] Electrification of AIT, #c., by bubbling through Water. 339 



8. In experimenting with the same apparatus* in 1890 it was 

 found that the water jet gave negative electricity to the ordinary air 

 of the laboratory enclosed in the vat. The present experiments fully 

 confirm this result, showing a gradual negative electrification of the 

 enclosed mass of air rising to about 5 volts in an hour, once every day 

 for the first few days. For twenty-eight days after the vat was set up 

 in October, 1894, fifteen observations of an hour each were taken, 

 to find the effect of the water-dropper, with no other disturbing 

 influence on the unchanged volume of air inside the vat. These 

 experiments verify the conclusion (' Phil. Mag.,' August, 1890) that 

 the more the air inside the vat became free of dust, the less became the 

 rate at which the air was negatively electrified by the water-dropper. 



9. On the 15th October last the vat was lifted from the tray to 

 remove some obstruction in the nozzle of the water-dropper, which 

 was not then flowing freely. Curve (6) was obtained that afternoon. 



CURVES 6 AND 7. 



* ' Phil. Mag,,' August, 1890, " Electrification of Air by a Water Jet," by Maclean 

 and Goto. 



