86 
DE. A. MATTHIESSE^f AND DE. M. H0LZ:kIA2i'^’ OX THE 
III. Copper, galvanoplastic commercial, not fused . h. 
U- 
IV. Copper No. 3, fused in a porcelain tube in hydrogenj^' 
V. Copper No. 3, fused, as will be presently described 
The mean of the above twelve determinations gives 93‘08 at I8°‘9 for the conducting 
power of pure copper. 
Peltiee* and others have already observed that annealed copper wire conducts 
better than hard drawn wire ; and on repeating the experiments with hard drawn wii-es 
from copper No. 2, and which were annealed in a current of pure hydi’ogen, we found 
the following numbers : — 
I. Hard drawn .... 95‘31 at 11 ’0 
Annealed 97‘83 at ll’O 
II. Hard drawn .... 95‘72 at ll’O 
Annealed 9 8 ‘02 at 11 ’0 
which makes a difference in the conducting powers of hard drawn and annealed wires 
of about 2 '5 per cent. ; much greater, however, is the difference between hard drawn and 
annealed silver wires, as the following experiments show : — 
Means. 
92- 24 at 18-0'| 
93- 01 at 18-5!>93-02 at 18-4 
93-81 at 18- 
92- 22 at 19-3 
93- 30 at 19-3 
92- 57 at 17-8 
93- 40 at 17-2 
92-76 at 19-3 
92-99 at 17-5 
I. a. Hard drawn 
h. Annealed 
II. a. Hard drawn 
h. Annealed 
95-28 at 14-6 
103-98 at 14-8 
95-36 at 14-6 
103-33 at 14-6 
We will now proceed to describe what is the effect of the metalloids, and afterwards 
of the metals, on the conducting power of copper. 
1. Effect of Oxygen {Suboxide of Copper). 
Copper readily absorbs oxygen from the air when in a fused state ; and it is supposed 
to be present as suboxide, which it retains very obstinately ; and in fact we may 
lead hydi’ogen over fused copper, in a porcelain tube, for hours without completely 
reducing the suboxide. It is also very difficult to prevent the oxygen being absorbed 
during casting, &c. In order to prevent all these sources of error, we thought that m 
making the alloys of copper by the following method, we might obHate them : — 
Fig. 1 shows the disposition of the apparatus. In the furnace-door communicating 
with a closed muffle are two holes ; through the upper one passes a glass tube connected 
* Ann. de Chini. et de Phys. Ivi. p. 371. 
