Electromotive Forces in the Voltaic Cell. 349 
Hlectromotive” Force of a Zine-Zinc, Dilute Sulphuric-Acid, 
Cell, of Resistance 4 ohm, through which the specified 
currents are driven by two or three Grove’s; each plate 
exposing 53 square centimetres on each face. 
Difference of | Observed E.M.F. 
Ourrent, in 5 of cell (obtained | H.M.F, calculated 
amperes, eee by adding rC to | from the formula 
; eet : the preceding e=—3C. 
S. 
column). 
552 — 37 — 26 — 276 
424 = eee — ‘25 — ‘212 
‘936 — 44 — 25 — 468 
“744 — ‘40 — ‘25 — 372 
1°88 —1:46 —1:08 — 94 
15 —1:32 —1:02 — "75 
2°4 —1-61 —1:13 —1-20 
1:97 —1-46 —1:07 — ‘99 
2:4 —1-'88 —1-40 —1:20 
1:94 —1:80 —1-41 — 97 
3°22 —2°10 —1°46 —1°61 
2°68 —1°88 —1:34 —1:34 
3°36 — 2°22 —1:55 —1:68 
4:24 — 2°40 —1:55 —2°12 
The agreement between the observed and calculated columns 
is not very bad ; and the polarization H.M.F. does not show 
decided signs of breaking away from the law of simple pro- 
portion until a current-strength of 4amperes is reached—say an 
intensity of ‘04 ampere per square centimetre of total surface. 
Electromotive Force of a Zine- Copper, Dilute Sulphuric-Acid, 
Cell, of Resistance £ ohm, through which the specified cur- 
rents are driven by two or three Grove’s; each plate 
exposing 53 square centimetres on each face. H.M.F. 
reckoned positive when it helps the current forward, nega- 
tive when it opposes it. 
Difference | Observed H.M.F. H.M.F. cal- 
Current, in | of potential | of cell (obtained | E.M.F. calculated| culated from 
amperes, | between ter- | by adding rC to | from the formula | the empirical 
C. minals, in the preceding e= "8-40. formula 
volts. column), e='D8—4C. 
55 + 24 +°35 +66 =a 
“94 +. 078 4°27 +54 +°39 
‘76 + °108 +:26 +61 oe 
1:88 — ‘045 +°33 +°33 +°20 
1-52 + -045 +°35 +42 +27 
2°4 — 195 +28 +°20 +10 
2:0 — 024 +°38 +°30 +18 
2°4. — 42 +°06 +-20 +10 
1-98 — 221 +18 +30 +18 
3°22 — 675 —°031 —°05 — 06 
2-75 — 75 — 2 —‘1l +03 
4:16 —1-04 — 21 — 24 — 25 
344 — “75 — “06 — ‘06 — ll 
Phil. Mag. 8. 5. Vol. 19. No. 120. Adfay 1885. 2B 
