92 ON THE ELECTEIC CONDUCTINO POWEE OE PUEE COPPEE AND ITS ALLOTS. 
The quantity of lead and tin remaining was so small that it was not possible to deter- 
mine it quantitatively. 
The experiments, however, tend to prove that on the addition of ti-aces of lead, &c. 
to copper containing suboxide, a relatively purer metal is obtained. 
From the foregoing experiments, we may conclude that there is no alloy of copper 
ivhich conducts electricity better ilian pure copper; and in conclusion, in order to be able 
to compare their results with those of others, we would call the attention of experi- 
menters — 
I. To the importance of stating whether the wires experimented with are hard drawn 
or annealed, as it makes in some cases a very marked difference in the values obtained. 
II. To the influence of temperature on the conducting power. We find m very few 
cases the temperature stated at which the observations har e been made. 
