90 
DR. A. MATTHIESSEX AND DR. M. HODZAr ANN ON THE 
had we had draw-plates with finer holes at our disposal, we might have drawn it much 
finer, — a fact, which does not at all agree with the assertions lately made, that copper 
with a small amount of arsenic cannot be drawn into fine wire. The arsenic was deter- 
mined as arseniate of magnesia. The following values show that arsenic greatly reduces 
the conducting power of copper : — 
I. Copper with 5*40 per cent, of arsenic 
6T7 at 16 ’Tl 
6T9 at 17‘0 J 
Means. 
6-18 at 16-8 
II. Copper with 2’80 per cent, of arsenic 
III. Copper with traces of arsenic . . 
fa. 12-97 at 18-8'| 
1^. 13-38 at 19-4j 
13-14 at 19-1 
fa. 57-72 at 19-5 
Ij. 57-89 at 19-9 
57 - 8 O at 19-7 
6. Effect of Heating in a current of Ammonia. 
Several experimenters state, that when copper is heated in ammonia, the gas is decom- 
posed and nitride of copper formed, a fact which Scheottee* disputes, and has been 
proved totally incorrect by Dick. We repeated the experiment by heating a copper 
wire, whose conducting power had been previously determined, for a quarter of an hour 
in a current of dry ammonia ; when cold, the conducting power was found the same, and 
the wire was as ductile as before. In all probability the reason why in the experiments 
of previous observers the copper became brittle, was (as already suggested by Dick) 
that they used copper containing suboxide. 
7. Effect of the Metals. 
The electric conductivity of copper is not so much impaired by the presence of small 
quantities of foreign metals as by that of the metalloids ; it is, however, very considerably 
diminished by iron and tin. 
The union of the copper with the other metals was effected in the manner before 
described, which offers in this case the additional advantage, that, by the constant move- 
ment caused by the hydrogen in the melted metals, the most intimate combination 
results. The amount of the metals thus alloyed with the copper was determined by 
analysis. 
o Means. 
I. Gopperf alloyed with 3'20 per cent, of zincj g^-oi at IO-g}^^ ^ 
6-25 at 15-2 
6*45 at I 6-4 
III. Copper with traces of zinc ^185-05 at 19-0 
^ ^ LJ. 84-43 at 20-0J 
|76-35 at 15-8 
II. Copper with 1-60 per cent, of zinc 
(a. 7 
lb. 7 
* Gmelin, vol. iii. p. 416. 
X All the metals employed were pure. 
t AU wii-es hard drawn. 
