142 THE SCIENTIFIC PAPERS OF 



ON THE DEPENDENCE OF ELECTRICAL RESISTANCE 

 ON TEMPERATURE. 



BY C. WILLIAM SIEMENS,* D.C.L., F.R.S. 



PART FIRST. 



ON THE INFLUENCE OF TEMPERATURE UPON THE ELECTRICAL 

 RESISTANCE OF METALLIC CONDUCTORS. 



THE experimental researches hitherto published on this subject 

 have been limited to temperatures ranging from the freezing to 

 the boiling point of water, and great uncertainty still prevails 

 regarding the law of increase at temperatures exceeding 100 

 Cent. 



The early experiments made by Arndsten f and Dr. Werner 

 Siemens \ tend to show that copper, silver, and other pure metals 

 offer electrical resistances which increase with the temperature in 

 an arithmetical ratio within the limits of their experiments, which 

 extended from to 100 Centigrade, whilst subsequent researches 

 by Dr. Matthiessen indicate a slightly divergent ratio between the 

 same limits of temperature. 



Platinum, which is, in many respects, a suitable metal for 

 extending these enquiries to higher temperatures, has been left 

 out of consideration in the otherwise exhaustive researches of 

 Matthiessen, and when I first directed my attention to this metal, 

 I observed very extraordinary differences in the electrical conduc- 

 tion of different specimens. 



PLATINUM WIRE. I found it impossible to obtain platinum wire 

 of such a degree of purity that its co-efficient of increment should 

 have a value corresponding with that of silver, and the other pure 



* Excerpt Journal of the Society of Telegraph Engineers, Vol. III. 1874, pp. 

 296-338. 



f Vide Annal. de Chimie, Vol. LIV. 1858, pp. 440-443. 



t Vide Pogsendorff s Annalen, Vol. CX. p. 1, Vol. CXII. p. 353. 



