ON STANDARDS OF ELECTRICAL RESISTANCE. 125 
date and June 14th, 1863, when they were last tested. During the time 
when not used, they were hung up in a room where in the winter a fire was 
kept all day, so that the temperature may have varied at times some 10 or 
12 degrees in the twenty-four hours. 
The following Table contains the results of the first and last comparisons. 
I have taken the conducting power in the first in all cases equal to 100 as 
compared with No. 19; in the last I have assumed that the conducting 
power of No. 15 has remained unaltered :— 
Conducting 
Conducting powers found, as__| power found, as 
compared with No. 19= 100. compared with 
No. 15=100. 
if 2. 3. 
May 9, June 14, 
is62,.| © |" i863,°| 7 T. 
1. Silver: hard-drawn ............ | 100-00 | 20:2 | 103-700 | 20-0 | 103-915] 20-0 
2. Silver: annealed ............... 100-00 | 20-2 | 99-740 | 20:1 | 99-947] 20-1 
3. Silver: hard-drawn ............ 100-00 | 20:2 | 102:590 | 20-2 | 102-807} 20:2 
4. Silver: annealed ............... 100:00 | 20°2 | 99-825 | 20:0 | 100:031| 20-0 
5. Copper: hard-drawn ......... 100:00 | 20-1 | 100-040 | 20:2 | 100-248} 20-2 
6. Copper: annealed............... 100:00 | 20:1 | 99:807 | 20:0 | 100-015} 20-0 
7. Copper: hard-drawn ......... 100:00 | 20:0 | 99-941 | 19-8 | 100:149| 19-8 
8. Copper: annealed............... 100:00 | 20:0 | 95:358 | 20-4 | 95:556| 20-4 
9. Gold: hard-drawn ............ 100:00 | 20:0 | 99-838 | 20-2 | 100-045] 20-2 
10. Gold: annealed ............... 100:00 | 20:0 | 99-855 | 20-0 | 100-062} 20-0 
11. Gold: hard-drawn .. ......... | 100:00 | 20:0 | 99-662 | 20:2 | 99-869] 20-2 
12. Gold: annealed ...,........... 100:00 | 20:0 | 99-670 | 20°33 | 99:877| 20:3 
13. Platinum: hard-drawn ...... 100:00 | 20:0 | 99°744 | 20:2 | 99-951} 20:2 
14. Platinum: hard-drawn ...... 100:00 | 200 | 99-792 | 20:2} 99-999} 20-2 
15. Gold-silver alloy: hard-drawn) 100-00 | 20:0 | 99-793 | 20:2 | 100-000} 20-2 
16. Gold-silver alloy: hard-drawn| 100:00 | 19:9 | 99-756 | 20:3} 99-963] 20:3 
17. German silver: annealed...... 100:00 | 20°3 | 99-955 | 20-0 | 100°162| 20-0 
18. German silver: annealed...... 100-00 | 20:3 | 99-938 | 20:0 | 100-145! 20-0 
Weeererman silver: annealed......| ..:ce. | cscsce | aseoee | secene 100:217| 20-2 
From the above it would appear that if the conducting power of No. 19 
has remained constant, that of all the others has altered; but supposing 
such to be the case, it will be found on comparing the values that the con- 
ducting powers have all altered in a like extent. Is this probable? Is it 
not more probable that the conducting power of the German silver has 
changed, than that that of all the others should have altered in the same 
degree? IPfthat o: the gold-silver alloy, No. 15, be called 100-00 instead of 
99-793, then, as will be seen from column 3, very few show any change in 
their conducting power. Those which show no sensible change are as follows :— 
Values taken from column 8. 
No. 2. Silver: annealed.............; 99-947 
No; @4. Silver: annealed. . ...rccves: so » 0's 100-031 
No. 6. Copper: annealed ............ 100-015 
No. 9. Gold: hard-drawn............ 100-045 
Nor 10:sGold = annealed .ioivejsc... sc. 100:062 
No. 18. Platinum: hard-drawn........ 99-951 
No. 14. Platinum: hard-drawn........ 99-999 
No. 15. Gold-silver alloy: hard-drawn .. 100-000 
No, 16. Gold-silver alloy: hard-drawn .. 99-963 
