[ 85 ] 
V, On the Effect of the presence of Metals and Metalloids upon the Electric Conducting 
Eoicer of Pure Copper. By A. Matthiessen, Ph.I)., and M. Holzmann, Ph.I). 
Communicated by Professor Wheatstone, F.B.S. 
Eeceived March 14, — Bead April 26, 1860. 
As the electric conducting power of copper varies so much according to different experi- 
menters, we thought it would be of some interest to study the causes of these differences ; 
and on comparing the values found for copper, we find that, taking silver =100, copper 
conducts according to 
Becqveeel* EiEsst LENzf; Davt§ Cheistie§ Haeeis§ Beee|| Potjillet^ Aendtsen** 
95-3 67-2 73-4 91-2 66-0 100-0 95-4 73-0 98-7 
The temperatures at which the above observations were made are only given in the 
cases of Becqueeel, Lenz and Aendtsen, who compared copper at 0° C. with silver at 
0° C. =100. 
We prepared therefore pure copper, — 
1. By precipitating with sulphuretted hydrogen the purest commercial sulphate of 
copper dissolved in water acidulated with sulphuric acid, dissolving the washed sulphide 
in nitric acid, precipitating at a boiling temperatui’e by carbonate of soda in excess, and 
finally reducing the oxide of copper with pure hydrogen. 
2. By precipitating sulphate of copper galvanoplastically by a very weak current. 
We have also tested the galvanoplastic copper of commerce, and have found that its 
conducting power is the same as that of the copper we prepared.. 
The method used for the determinations was the same as that described in the Philo- 
sophical Magazine (February 1857). The diameters of the wires used were about 0-25 
to 0-5 millim., and the lengths from 0-5 to 1-5 metre; and of each specimen of copper 
or alloy two or three determinations were made with -wires of different diameters. 
The following are the results obtained with pure copper, compared with a hard drawn 
silver wire =100 at 0° C. (all the wires were hard drawn): — 
Means. 
93-00 at 18-6 
I. Copper purified by the above method (1) 
a. 92-63 at 18-0 
b. 93-36 at 19-2 
II. Copper, galvanoplastic, not fused . . 
* Ann. de Chim. et de Phys. Ser. 3. vol. xvii. p. 242. 
t Poggendoeee’s Annalen, vol. xlv. p. 20. 
§ G-melix, vol. i. p. 289. 
Mvilee, Lehrbuch der Pbysik, p. 202. 
MDCCCLX. N 
r«. 93-81 at 19-7'j 
,<5. 93-56 at 20-5 >93-46 at 20-2 
[c. 93-00 at 2 O- 4 J 
J Ibid. p. 105. 
II Btjee, Griindriss der Pbysik, 348. 
** Poggexdoeee’s Annalen, vol. cv. p. 1. 
