TEMPEEATIJILE ON THE ELECTEIC CONDTJCTINO POWEE OF METALS. 
For first wire . X=l*4535 — 0’0052883^+0‘00001060^^ 
For second wire X=1'4049— 0‘0047972#+0'000006453^^ 
For thii-d wire . X=l-4603-0-0051286^+0-000007737f. 
From the above we see how bismuth increases in conducting power after being kept 
at 100'’ for one day. This increment is so rapid that it may be followed for the first 
two hours from five to five minutes. Wire 1 altered by one day’s heating 16 per cent . ; 
wire 2, 19 per’cent. ; and wire 3, 12 per cent. Wires 1 and 2 were cut from the same 
piece. 
This behaviour explains why the conducting power of bismuth wires varies so much : 
for in the paper so often here alluded to, the maximum difference between twelve wires 
was found to be 22 per cent. In pressing the wires the heat applied to the press is 
never constant ; so that, if pressed very warm, wires of high conducting power would 
probably be the result. The conducting power of bismuth was found equal to 
o Eeduced to 0°. 
1-19 at 13-8 1-2484 
Taking the mean of the values as before, we find the formula for bismuth to be 
X=:l-2454-0-0043858^+0-000007134f. 
3Iercii7'^. 
Purified by allowing a solution of subnitrate of mercury to stand over the metal for 
several weeks, during which time it was often well shaken up with it. The determina- 
tions were made in a calibrated thermometer-tube, to the ends of which wide glass tubes 
(13 to 14 millims. wide) were fused and bent, as shown ha fig. 3. Mercm-y prepared at 
different times was used for the determinations. For the 
experiments, the tube was filled with hot mercury, and its 
resistance was determined when cold. This was twice re- 
peated ; and the resistance being found the same each time, 
it was assumed that the tube filled in this manner did not 
contain air-bubbles ; this is also proved by the close agree- 
ment of the formuloe found in the two cases for the variation of the conducting power 
at higher temperatures ; for if in either case air-bubbles had been present, the formulee 
must have differed to a much greater extent, as it can scarcely be assumed that in the 
two cases the bubbles were equal in bulk. The mercury was connected with the appa- 
ratus by amalgamated copper wires (4 to 5 millims. thick). Table XIl. shows the 
results obtained. 
