22 Mr. Harris on the relative powers of various 
2ndly. Considering silver and copper as the best conduc- 
tors, (being the least heated by the explosion) then the 
conducting power of 
Gold to copper or silver is 
as 
2 : 3 
Zinc or brass to copper or 
silver 
1 : 3 
Platinum or iron to copper or silver - 
1 : 5 
Tin to copper or silver 
- 
l : 6 
Lead to copper or silver 
- 
1 : 12 
3rdly. It may be observed that the conducting power of 
metals, when alloyed, is variously affected : thus the con- 
ducting power of gold and copper, or gold and silver, when 
alloyed together, is less than either of these metals in a 
separate state ; and the difference in the conducting power 
increases with the quantity of the inferior conductor alloyed. 
Thus, gold one part, with copper three parts, had its tempe- 
rature raised to 15 0 of the scale; gold and copper in equal 
parts to 20 0 ; gold three parts, with copper one part, to 25 0 : 
the same may be said of gold and silver ; whilst an alloy of 
copper and silver, in similar proportions, does not vary from 
either of the metals separately. 
Tin and lead, alloyed, appears to give a conducting power 
formed by that of each metal taken singly, and varying, as 
above, with the quantity of the inferior conductor ; thus, an 
alloy of lead and tin in equal parts, gives an effect equal to 
one-half the effect on tin, added to one-half the effect on lead, 
and so on ; the same may be said of zinc and tin. 
4thly. It is observable that a very small quantity of alloy 
may influence materially the conducting power ; thus copper 
alloyed with only one-eighth part of its weight of tin, becomes 
