154 Mr. F. Jenkin Report on the New Unit [April 6, 



novel method of chemical research which I have here exemplified may be 

 considered of sufficient interest to be followed out by other investigators, 

 and believing that the experiments and suggestions which I have here 

 given, and the principles they involve, are calculated to throw some light 

 on the nature of those chemical processes which take place in nature, 

 whether in organized bodies or in the crust of the earth, neither of which 

 branches of natural chemistry is at present sufficiently understood, and 

 both of which it is of very high interest further to elucidate. 



April 6, 1865. 



Major-General SABINE, President, in the Chair. 

 The following communications were read : 



I. " Report on the New Unit of Electrical Resistance proposed and 

 issued by the Committee on Electrical Standards appointed in 

 1861 by the British Association." By FLEEMING JENKIN, Esq. 

 Communicated by Professor A. W. WILLIAMSON. Received 

 March 20, 1865. 



Sir Humphry Davy, in 1821*, published his researches proving a 

 difference in the conducting-power of metals and the decrease of that 

 power as their temperature rose. This quality of metals was examined by 

 Snow Harris, Gumming, and E. Becquerel, whose table of conducting- 

 powers, compiled by the aid of his differential galvanometer, and published 

 in 1826f, is still frequently quoted, and is indeed remarkable as the result 

 of experiments made before the publication by Ohm, in 1827, of the 

 true mathematical theory of the galvanic circuit. 



The idea of resistance as the property of a conductor was introduced by 

 Ohm, who conceived the force of the battery overcoming the resistance of 

 the conductors and producing the current as a result. Sir Humphry 

 Davy, on the contrary, and other writers of his time, conceived the voltaic 

 battery rather as continually reproducing a charge, somewhat analogous to 

 that of a Ley den jar, which was discharged so soon as a conductor allowed 

 the fluid to pass. The idea of resistance is the necessary corollary of the 

 conception of a force doing some kind of work , whereas the idea of con- 

 ducting-power is the result of an obvious analogy when electricity is con- 

 ceived as a fluid, or two fluids, allowed to pass in different quantities through 

 different wires from pole to pole. When submitted to measurement, the 



* Phil. Trans. 1821, vol. cxi. p. 425. 



t Ann. de Chirn. et de Phys. vol. xxxii. 2nd series, p. 420. 



{ Die galvanische Kette, mathematisch bearbeitet, 1827; also Taylor's Scientific 

 Memoirs, vol. ii. p. 401. 



The writer does not mean by this that electrical and mechanical resistance are truly 

 analogous, or that a current truly represents work. 



