108 Mr. R. Phillips on the Electricity of Condemation. 



88. I have not obtained any effect by discharging air with 

 the steam from the boiler. My experiments were usually 

 made by pumping air into the boiler, and discharging the 

 mixture of steam and air through the brass jet, the pressures 

 being generally low. At a pressure of 40 lbs. on the inch, 

 the difficulty of getting air into the boiler was so great that 

 my experiments are not satisfactory ; and certain capricious 

 results were obtained, which I feel sufficiently convinced at 

 present were produced by water being deposited in the dis- 

 charging passages. 



89. The arrangement (54.) was restored, and the tube was 

 brought up close to the brass connecting piece, by which the 

 end of the tube was partly closed. The steam was also at 

 40 lbs. on the inch. The wire-gauze being held in the steam 

 as it issued from the tube, and then removed to the single-leaf 

 electrometer, was found to have become negative. The piece 

 of a gun-barrel was now substituted for the glass tube ; the 

 steam was also negative. These two experiments are merely 

 variations of that formerly described (47.). It was singular 

 to observe how suddenly and completely the electrical pro- 

 perties of the steam were changed by moving the gun-barrel 

 or glass tube out from the brass connecting piece. 



90. From the foregoing experiments, 1 think it follows that 

 the electricity of condensation (51, 52, 56,84, &c.) is developed 

 by drops of water moving either with, or contrary to the elec- 

 tro-current of condensation (11, 14, &c.). 



91. I conclude from (90.) tliat rain is necessary to the for- 

 mation of lightning, and from (86.) that the drops of rain need 

 not possess any very great velocity. 



92. As to the connexion of lightning witli rain, I have but 

 to refer to Mr. Birt's paper (Phil. Mag., vol. xxxv. p. 161); 

 and with regard to the connexion of mist with the aurora, I 

 refer to M. De la Rive's paper (Phil. Mag.,vol.xxxiv. p.291). 



93. It has been suggested by Sir John Herschel that the 

 light of the sun may be produced by electric currents; and is 

 it impossible that these currents may be of the same nature 

 as our lightning and aurora? The sun has a dark body, an 

 atmosphere, and a difference of temperature. 



7 Prospect Place, Ball's Pond Road, 

 January 10, 1850. 



