146 REPORT—1862. 
78:0 at 0° 78-2 at 0° 76:8 at 0° 
79-5 at 0° 78:3 at 0° 76:7 at 0° 
77:0 at 0° 78:0 at 0° 77:3 at 0° 
These values agree together as well as might be expected, considering that 
0-01 per cent. impurity would cause these differences. Now the values 
obtained by different observers vary between the numbers 59 and 78. 
If we now take the case of copper, the values found by the same experi- 
menters* for different preparations of the pure hard-drawn metal were— 
99-9 at 0° 99-4 at 0° 99-8 at 0° 
101-0 at 0° 99:4 at 0° 100-3 at 0° 
99-8 at 0° 99-9 at 0° 100-0 at 0° 
99-9 at 0° 
They were drawn by themselves, and all, with one exception, electrotype 
copper. 
It is well known how differently the so-called pure copper conducts when 
prepared by different experimenters. In the following Table, in order to 
show these facts more clearly, we have given the conducting powers of the 
metals, taking that of silver equal 100 at 0°. Silver, copper, gold, and pla- 
tinum were hard-drawn. All values given, except where the contrary is 
mentioned, have been reduced to 0°, 
Siemens. Lenz. Becquerel. | Matthiessen. 
Silver Peele. 2 100 100 100 100 
Copper ..vessecseess 96-9 73-4 95:3 999 
iy A keae. dsereeck a fhistores 585 66°9 780 
PERT eee Ae ae Ce eee 26°3 23°7 
WANG ecetversereceseW ta Leeeseee © Ln peesies 25°77 29°0 
EDEN cecauerogssrsgessf) le pestes 22°6 15:0 12°3 
WTO feycseseses|) cesses 13°0 131 14°4 at 20°4 
HCC RIES, <b dees eb ented 10°7 88 83 
Platinum .,........ 14°2 10°4 86 10% at 20°7 
Mercury ........... 1-72 3°42 at 18°9 1°86 1°65 
If now mercury be taken as unit, we find the following values :— 
Siemens. Lenz. Becquerel. Matthiessen. 
Silyer 4 ies Sencar 58:20 29°24 53°76 60°60 
GOppetrere.ss52-5- 56°40 21:46 51:23 60°55 
EEG EE oe incite Sena ad) 17:10 37°04 47°27 
Gadlntinrntaccrc ls cok cccc eels Gorse 1414 14°42 
ANG) scoectnansescnit Ss kavpete, fe al pe. saeco 13°82 17-70 
EPs cee tacseatitee 6°59 8:10 TA5 
Tronh.-. be kideshe.s | "Roe 3°80 7°04 8°72 at 20°4 
Bpad 2 BES, BHR 3°12 4-73 503 
Platinum .......... 8:25 3°04 4°62 6°36 at 20°7 
Mercury ........... 1:00 1:00 at 18:7 1:00 1:00 
A glance at the foregoing Tables will suffice to show how badly Lenz’s 
series agrees with the rest when mercury is taken as unit; and, in fact, we 
obtain more concordant results if, in the above series, we take any other metal 
* Phil. Trans. 1862, p. 9. 
+ This and the following Table have been copied from a paper published in the Phil. 
Mag. for Sept. 1861. 
