ELECTEIC CONDUCTIXa POWEE OE PIJEE COPPEE AND ITS ALLOTS. 
89 
2. Effect of Carbon. 
According to Kaestejst*, copper takes up 0-2 per cent, of carbon; we could not, how- 
ever, obtain wires containing more than 0*05 per cent. This small quantity causes the 
conducting power to decrease considerably. Thus galvanoplastic copper in small pieces 
was fused down with lamp-black, and gave, upon analysis, 0*05 per cent, of carbonf ; 
and for the conducting power we found 
Mean. 
74-91 at 18-3 
74- 29 at 18-11 
75- 53 at 18-5/ 
3. Effect of Phosphorus. 
Phosphorus alters the properties of copper to a very great extent ; it becomes very 
much harder, and its tenacity is greatly impaired. Of all the impurities, this has the 
greatest reducing effect on the conducting power of copper. 
Eed phosphorus was thrown on melted copper in a tobacco-pipe and re-fused. The 
amount of phosphorus was determined as phosphate of magnesia. 
I. Copper with 2-5 
per cent, of phosphorus' 
a. 
h. 
7-37 at 17-01 
7-11 at 18-Oj 
Means. 
7-24 at 17°-5 
II. Copper wdth 0-95 per cent, of phosphorus 
a. 23-43 at 22-3 
h. 23-05 at 22-0 
23-24 at 22-1 
III. Copper with 0-13 per cent, of phosphorus 
CL 67-88 at 20-0 
h. 67-46 at 20-0 
67-67 at 20-0 
4. Effect of Sulphur, Selenium, and Tellurium. 
Sulphide of copper does not appear to dissolve in copper, but merely to mix with it 
mechanically. It makes the copper very brittle ; and although we succeeded in draw- 
ing a wire which contained, according to the analysis, 0-18 per cent, of sulphur, the 
values obtained for the conducting power did not agree at all with each other. The 
mean of four determinations gave 88-58 at 19°-4. 
Traces of selenium and tellurium make copper so rotten that we were unable to 
draw it. 
5. Effect of Arsenic. 
When arsenic is thrown upon melted copper the greater part of it is absorbed, whilst 
a part volatilizes ; and on re-fusing the alloy formed, if a large quantity of arsenic has 
been used, it has a dingy grey colour-, and is very hard and brittle. We managed to 
draw an alloy containing 5-40 per cent, of arsenic to the diameter of 0-29 millim. ; and 
* Scbcweiggee’s Journal fiir CLemie u. Physik, Ixvi. p. 395. 
t We repeated this experiment several times, but could not again make tbe alloy. In aU probability, 
therefore, tbe carbon found 'was only mechanically mixed with copper. 
