712 Proceedings of Royal Society of Edinburgh. [mss. 
worked out almost to the of an ohm. They worked out also^ 
very closely when I paired zinc and platinum together, and also 
when I paired lead and antimony, but not at all when gold was. 
tried with either silver, copper or aluminium, nor when zinc or 
platinum, lead or antimony, were paired with any of those metals. 
I found, though, that if I multiplied the resistance found for gold^ 
when paired either with silver, copper or aluminium, by 2, the 
result would he very close to the observed resistance ; and also 
that if zinc or platinum were tried with either silver, copper or 
aluminium, and the result multiplied by 5, it would be very close 
to the observed resistance ; and further, if either zinc or platinum 
were tried with gold, the result had to be multiplied by 2J to- 
bring the resistance of the two former metals up to the observed. 
Similarly the resistance of lead and antimony, though working out. 
very closely when paired with one another, had to be multiplied by 25 
when paired with either silver, copper or aluminium, and when paired 
with gold by 12J, so that the rule had to be modified as follows : — 
Rule to Find the Electrical Resistance op Different Metals, 
1st. It is inversely as the square of the cube roots of the atomic 
weights; 
2nd. Directly as the melting points in the scale of absolute 
temperature ; and 
3rd. Directly as the atomic volume. 
The result to be multiplied by 2 when gold is paired with either 
silver, copper, or aluminium ; by 3 when iron is paired with either 
of those metals ; by 5 when either zinc or platinum is paired with 
them; by 6 when nickel is paired with them; by 14 for tin; by 
25 for antimony or lead ; and, generally, by numbers proportional 
to their silver-copper-aluminium multipliers when paired pro- 
miscuously one with the other. 
37. These results delighted as well as disappointed me. They 
delighted me because it was my assumed knowledge of the 
constitution of atoms which led me to try this method of finding 
the electrical resistance ; and I could not suppose that they were 
mere coincidences, for they were too close and intricate for that.. 
I reasoned that if my atoms were real things, and not “mere 
