148 REPORT—1862. 
Pure copper. Thomson. Matthiessen. 
107-0 107-2 
2 107:5 105:9 
3 108-7 106°9 
+ 107-7 108-1 
The differences here, with the exception of alloy 6 and copper 2, may be 
due to the temperature at which the observations were made not being in 
both cases the same; for 2 or 3 degrees’ difference will account for them. 
The Table, however, shows that different observers do obtain the same values 
for the conducting power of the same wires. 
The yalues obtained for the conducting power of the gold-silver alloy, 
rade by different persons, of different gold and silver, are given in the fol- 
lowing Table— 
Alloy. Hard-drawn. Annealed. 
i 100°3 100:6 
2 100-2 100-7 
3 98°8 99-2 
4 soot 100°2 
5 100-4 100°7 
6. 99-7 99-8 
7 1003 100°8 
8 100-1 100-4 
which shows, therefore, that the alloy may be prepared in a commercial 
way, and still have a conducting power which varies less than that of a pure 
metal prepared at different times by the same experimenter. If we look at 
the hard-drawn series, we find five out of the seven wires tested agree toge- 
ther exceedingly well, the greatest difference being only 0-3 per cent. These ~ 
five alloys were made, three in London, by scientific chemists, one in Frank- 
fort-on-the-Maine, and one in Brussels. Those which agree least with the 
others were made in New York (No. 3) and by a well-known assayer in Lon- 
don (No. 6). 
2. On its homogeneity and its molecular condition—If the wires of the 
alloy made and drawn by different persons were not homogeneous, the values 
obtained for the conducting power could not have agreed so well together. 
It has been already mentioned that some of the alloys determined by Thom- 
son, when redrawn, were found to have a different conducting power *. 
Conducting power of wire Conducting power 
Alloy. as received from the wire- after being re- 
drawer. drawn. 
1 100-0 100°0 
2 100-7 95:8 
3 103°9 102-9 
4 94-6 100°8 
5 96:0 98-1 
6 92-0 89-9 
7 74:7 86:0 
Pure copper. 100-0 98°6 
Of course, here again, some of these differences are due to the temperature 
in each case not being the same; but the differences found with the alloys 
2, 4, and 6 were undoubtedly due to faulty wires. It was for this reason 
* Proceedings of the Royal Society, Feb. 1861. 
