Condensation mth Lightning and the Aurora, 107 



13 inches, and of the other 3*5 inches. The shorter limb 

 stood before the brass jet, with its central line coinciding with 

 the central line of the path of the steam; the hole of this 

 smaller limb was also fitted with a bung having a hole in its 

 middle 1*3 inch diameter. The longer limb formed an angle 

 of about 25° with the horizon, and was attached to a glass rod 

 by which the tin pipe was insulated. The distance of the end 

 of the brass jet from the nearest part of the bung was 2*5 

 inches, and the tin pipe was connected with the single-leaf elec- 

 trometer. 



84. The above arrangement having been completed, the 

 fountain was held at about 8 'inches from the open end of the 

 longer limb, and a stream of water from the platinum jet di- 

 rected axially through the long arm of the pipe ; no electricity 

 was produced. Then while the water was flowing, the cock 

 of the boiler was turned a little, so that the steam might issue 

 from the jet under some very low pressure, perhaps a foot of 

 water : an abundance of positive electricity was now obtained ; 

 but on again shutting off the steam, no electricity. The boiler 

 was uninsulated. 



85. I found this electrical effect to increase as the pressure 

 was increased, always taking care to keep within the point at 

 which the boiler would have become negative. But that no 

 doubt should remain as to the state of the boiler, I have often, 

 immediately after having obtained the positive charge as above 

 from the steam, connected the boiler with the electrometer 

 and found it always positive. 



86. The longer limb of the tin pipe was now brought to an 

 angle of about 55° with the horizon, and instead of the foun- 

 tain I employed a pipette, which was kept at about 2 feet from 

 the end of the tin pipe ; everything else remained as before. 

 While the steam was escaping into the pipe, as in former ex- 

 periments (84', 85.), a slender stream of water was blown from 

 the pipette which fell in drops through the steam in the pipe ; 

 a positive charge was at once given by the water to the tin 

 pipe, although before the water fell through the steam there 

 was no effect produced on the electrometer. The boiler was 

 positive. 



87. An electrical effect was produced by blowing water 

 from the pipette on an insulated screen, the screen becoming 

 positive. The amount of electricity so obtained was very 

 variable under apparently similar circumstances, and fre- 

 quently nearly nothing for a great number of trials ; it was at 

 such times that the above experiments were made, the pipette 

 being examined as to its electrical powers both before and 

 after each experiment. 



