Heat and Static Electricity. 259 



sulphide of carbon ; the liquid is ignited, and the flame is held 

 above the electroscope charged with + electricity. At a dis- 

 tance of three or four inches immediate perfect and permanent 

 discharge takes place. 



§11. Experiment. — The same flames are found to discharge 

 the — electricity of an electroscope at about the same distance. 



§ 12. It will be noted that these flames included white lumi- 

 nous smoky (benzol), white luminous (ether), feebly luminous 

 (alcohol and bisulphide of carbon); They are all water-forming 

 but the last. There is little, if any, difference noticeable in their 

 power of discharge. A paper spill or wooden splinter answers 

 almost equally well. 



§ 13. Experiment. — The wire holding the cotton-wool satu- 

 rated with the liquids of § 10 is fastened to an ebonite pen- 

 holder, so that the flames are not in electric contact with the 

 earth. The power of discharging both + and — electricity of 

 an electroscope appears to be sensibly the same as when there is 

 earth-connexion, the discharge being quick, complete, and per- 

 manent at a distance of three or four inches. 



§ 14. The success of the above experiments with white-hot 

 balls depends upon the balls being of a bright white heat ; the 

 hotter the better. Complete success can be obtained in an ordi- 

 nary fireplace with a good draught if a blower be used. Ano- 

 malous results are obtained if sufficient care be not paid to this 

 point, as appears in the following paragraphs. 



§ 15. Experiment. — -A red-hot ball is hooked out of the fire 

 with the insulating hook and presented to the + conductor of 

 an electric machine in action, and then brought near to and into 

 contact with an electroscope. No charge is imparted (com- 

 pare § 1). 



§ 16. Experiment. — The conditions being the same as in 

 § 15, the — conductor of the machine is used; the electroscope 

 leaves diverge permanently with — electricity on completing the 

 contact. 



We have in this experiment the first decisive evidence of the 

 difference between the influences of hot iron on -f and — elec- 

 tricity. 



§ 17. Experiment.— As the red-hot iron ball on the insulating 

 hook gradually cools, it slowly acquires the power of receiving 

 from the machine and giving to the electroscope a charge of + 

 electricity. So that, with regard to -f- electricity, white-hot and 

 red-hot iron refuse to receive or convey a charge. With regard 

 to — electricity, white-hot iron alone does so. 



§ 18. Experiment. — A white-hot ball is hooked out of the fire 

 on a conducting hook ; and, as it cools, its power of inductively 

 discharging -f and — electricity is tested. Long after it has 



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