Intelligence and Miscellaneous Articles, 155 



pole of twelve Daniell's elements. The experiments were afterwards 

 repeated, when the air in the room indicated a negative charge, with 

 no difference in the results. 



At the suggestion of Dr. Wilcott Gibbs, Rumford Professor, I tried 

 the above experiments with a Bunsen blast lamp, by means of which 

 I could increase the heat and the flow of air and gas at pleasure. 

 Slight deviations in the scale-readings were obtained by this means : 

 the flow of air appeared to afi'ect the charge of electricity upon the 

 metallic tip, rendering it less constant. The above experiments 

 were in the main confirmed. The nature of the metallic plate sub- 

 mitted to the flame, and the degree to which it was heated, appeared 

 to have a very slight influence upon the charge. 



Sir "William Thomson, in the Proceedings of the Literary and 

 Philosophical Society of Manchester, March 1862, has a paper upon 

 the electricity of the air in rooms. He finds that it is generally 

 negative. By placing a spirit-lamp upon the prime conductor of an 

 electrical machine, he was enabled to change the tension of the air 

 from a positive to a negative state and the reverse. He carefully 

 separates the results obtained from the idioelectric eff'ect of the flame, 

 which, he states, in no case gave a tension equal to either pole of a 

 Daniell's element. 



During the past winter observations made in the laboratory tend 

 to confirm these views. I have, however, found on some days the 

 air within strongly positive. The room is in the north-west corner 

 of the building ; and there was a strong north-west wind blowing at 

 the times this was observed. I noticed, also, while experimenting 

 with the flame of a Bunsen burner placed near the water-dropper 

 used by Sir AYilliam Thomson in investigating the electrical state 

 of the atmosphere, that the positive charge of the air in the neigh- 

 bourhood greatly decreased, and in some instances became feebly 

 negative, by the presence of the flame. 



The popular idea that great fires are followed by a change in the 

 atmosphere inducing rain, does not seem to be unwarranted from an 

 electrical point of view. The electricity of the air during cloudy and 

 rainy weather is generally negative, or at the most feebly positive. 

 The flames bemg negative would tend to change a strong positive 

 charge in clear weather to a negative one, and thus bring the air to 

 the state noticed in cloudy and rainy weather. 



The following are the conclusions to which the above experiments 

 lead : — • 



1. The flame of a Bunsen burner is negative, while positive elec- 

 tricity accumulates on the burner itself, if it is a good conductor. 

 With orifices made of non-conductors, no charge was found upon 

 the tip. 



2. The stratum of air in contact with the outer cone of flame is 

 slightly charged with positive electricity. The partly consumed gas 

 of the interior cone is neutral. 



3. The presence of flames tends to change the nature of the atmo- 

 spheric electricity at the given place, reducing a positive tension to 

 a feebly negative one.— Silliman's American Journal for July 1S72. 



