1896-97.] Electrical Properties of Fumes from Charcoal. 313 
On Electrical Properties of Fumes proceeding from 
Flames and Burning Charcoal. By The Right Hon. 
Lord Kelvin, G.C.Y.O., F.R.S., and Dr Magnus Maclean. 
(Read April 5, 1897. ) 
§1. Many experimenters have investigated the electrical pro- 
perties of flames and incandescent solids. The methods usually 
employed have been (1) to examine the electric conductivity of 
different parts of the flame ; * (2) to measure the difference of 
potential between platinum wires in different positions in the same 
flame ; f (3) to find the leakage of a charged conductor when placed 
near, or in view of, a flame or an incandescent solid ; i (4) to 
observe the leakage of a conductor, raised to a red or white heat, 
by an electric current, and electrically charged ; § and (5) to 
observe the production of electrification or diselectrification by a 
glowing wire, through which a current is passing, in neighbouring 
insulated conductors separated from it by different gases. || 
§ 2. This short communication divides itself into three separate 
inquiries: (1) to test by one of our electric filters H the electric 
quality of the fumes from different flames and burnings (this 
method has not, we believe, been tried before) ; (2) to observe the 
difference of potential maintained between two wires of the same 
metal connected with a copper plate and a zinc plate when 
the fumes from different flames and burnings at different distances 
* Account of experiments in Wiedemann’s “ Lehre von del* Elektricitat,” 
vol. iv. B. Carl’s Rep., xvii. pp. 269-294, 1881. J. J. Thomson, Phil, Maq., 
pp. 358, 441, 1890. 
t Hankel, Phil. Mag., p. 542, December 1851 ; Phil. Mag., p. 9, January 
1860. Elster and Geitel, Wied. Ann., vol. xvi., 1882; also Phil. Mag., 
September 1882. Maclean and Goto, Phil. Mag., August 1890. 
X Guthrie, Phil. Mag., p. 308, April 1873. Giese, Wied. Ami., vol. xvii., 
1882 ; Worthington, “ On the Discharge of Electrification by Flames,” Brit. 
Assoc. Report, 1889, pp. 225-227 ; Schuster, Lecture Royal Institution, 
February 22, 1895. 
§ Guthrie, Phil. Mag., p. 237, October 1873. 
|| Elster and Geitel, Wied. Ann., xxxvii. p. 315, 1889; Elster and Geitel, 
Wied. Ann., xxxviii. p. 27, 1889. 
H Kelvin, Maclean, Galt, “Electrification and Diselectrification of Air,” 
Proceedings of the Royal Society, London, vol. lvii. , February and March 
1895 ; also B. A. Report 1895. 
VOL. XXI. 25/5/97 
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