308 The Rev. Dr. Rozinson on the Effect of Heat in lessening the 
STAAL le 0 4 RLS ee = AOL 
Mean oflene = 589.6. <a e OO Ne ee Bee LAS 
The probable error of the mean e is here = + 4.8, and the difference = 9.3. 
Of this I conceive 2.0 is accounted for by the 3°4 of higher temperature. The 
remaining 7.3 is 1.27 times the probable error of that difference (= + 5.73). 
The chances are, therefore, 3 : 2 that it zs error of observation. This does not 
exclude the probability of some effect being produced by the freer escape of the 
gases; but it does establish that the affinity is no¢ changed. The same may be 
said of the conducting power of the electrolyte. I was surprised at this result, 
because gas appeared under the action of a single cell, and with two its evolution 
seemed considerable. ‘The deflection, however, was only 0°.1 With three the 
action was powerful, and the deflection = 33°. 
This effect of heat on water is in singular contrast to its action on the affinity 
of metals, which does not change in the same circumstances. I have already 
stated that in Daniell’s cell the expression of the intensity is r= 2.0 — 2eu0. 
Examining this at the temperature 62°,a mean of 12 gives E= 275.0, r= 45.1; 
and on heating it to 162°.8, as measured by the mean of two thermometers, one 
in contact with the copper, the other immersed between two leaves of the zinc, 
the mean is E = 277.9, R= 27.3. The values of r must be considered identical, 
the slight difference arising from the easier diffusion of sulphate of copper in the 
hot liquid. The conducting power of the fluid, on the other hand, is increased 
considerably, and with it the power of the cell, the currents being 5.38 and 8.50. 
When excited with chloride of copper and hydro-chloric acid [had previously found 
B= 2280" 2). Ar 48:60 SS PROG 
Ei 2o(.o0 yak = 2.2) 5 2 SES N46 
Either these forces are unchanged, or the affinity of zinc changes in both cases 
just twice as much as that of copper, which seems very unlikely. 
With a cell excited by dilute sulphuric acid whose r= z.0 — cu.o — ho, I 
obtained similarly 
BS 1101. 12 Se RS SS S048 
ESS WS G8. 0k i MRSS Ts Ob 
hence there is a change of h.o = 26.6 for 95°.3, or 27.91 for 100°, a little larger 
* The pressure was less while the current of 45° passed, as less gas was evolved; its mean 
Sts: 
Leet PS 
=. + = 
on) Me 2 | 
“ 
= 
