52 Hi. Haug on the Electro-motive Force 
crease of resistance of the copper wire with decrease of observed 
intensities, the last horizontal row of figures making the only 
of observations, I suppose. If calculated for table x111, column 
3 is decreasing, column 4 increasing. If calculated for table x1v, 
both columns 3 and 4 are decreasing, from the mean of the first 
three values to the mean of the last three. 
It seems to me that the facts here illustrated, give a new rea- 
son for the great difference of the specific resistances of conduct- 
ors, as derived by different observers from experiments, under 
conditions much varying and either partly ncteie or at least 
underrated in their influence. From observations of Davy, Bec- 
querel, Ohm, Christie, Lenz, Pouillet, Buff, Frick, Miiller, Lamy, 
Arndtsen, Matthiessen and Wie demann, as recorded in G. W iede- 
. * . ’ 
which the conducting power of silver is taken as 100. The val- 
ues vary 
For copper between the limits 65°8 and 280°9, ratio 1 to 4:27 
“ gol 6 “cc ‘“c 5572 6 8, 6 
5 L: « O98 
“ zinc “cs 6 oc 94°06 “6 93°6, “ 1 “ 3°88 
“ tin “ “cc os 11°45 “ 47:2, 4“ eS bb 4°12 
“ n “c 66 “ 12°35 48:9, “ 4 & 3-06 
“platinum ad = 793" A480, «3 * 606 
“a ea “ “ a“ vera “ 63°3 Ee 8-15 
“cs antimony ac “cr “cc : 4 29 “c 6°5, “ - “e 151 
“ mercury se eee 163 “ £en, "1 > 380 
Ce ee Oe 2 hee EECA Bee 
While oe method of calculation - —— (Cu), (R) vee Ae 
of tables X to XIV, gave the appearance of the ratio of in 
resistance, ee “ is “66. The s same true internal resist- 
ance at low intensities, may bs calculated either by the formula 
(Ry (E2 St ae 
I,-l, 
with the same observations, (Cu) has been calculated, as per page 
51; or, the values for (Cu) computed there, and s specified j in col- 
umns 3 and 4, on page 51, may simply be deducted from the cor- _ 
responding mean values of the whole internal resistance of table 
