Table 294 {continued). 263 



COMPOSITION AND ELECTROMOTIVE FORCE OF VOLTAIC CELLS. 



Name of cell. 



Negative 

 pole. 



Solution. 



Positive pole. 



E. M. F. 



in volts. 



(1)) Single Fluid Cells. 



I^clanche . . . 



Chaperon . . . 

 Edison-Lelande . 

 Chloride of silver 

 Law 



Dry cell (Gassner) 

 Poggendorff . . 



J. Regnault . 

 Volta couple 



Amal.zinc 



t< « 



Zinc . 



Amal. zinc 



Zinc 



Solution of sal-ammo- 

 niac 



Solution of caustic 

 potash 



23 % solution of sal- 

 ammoniac .... 



ipt.^ZnO, ipt.NH4C],'^ 



3 pts. plaster of paris, 1 



2pts.ZnCl2,and water [ 



to make a paste . . J 



Solution of chromate I 



of potash .... 5 



12 parts K2Cr207 + ) 



25 parts H0SO4 -f- > 



100 parts H2O . . ) 



I part H2SO4 + j 



12 parts H2O -f- V 



I part CaS04 . . ) 



H2O 



(Carbon. Depolari- 

 zer : manganese 

 peroxide with 

 powdered carbon 

 5 Copper. Depolar- 

 1 izer : CuO . . 



( Silver. Depolari 

 ( zer: silver chl'ride 

 Carbon . . 



Cadmium 

 Copper . 



1.46 



0.98 

 0.70 

 1.02 

 1-37 



1-3 



1.08 

 2.01 



0-34 

 0.98 



(c) Standard Cells. 



Weston normal 



Clark standard 



(Cadmi'm) 

 ( am'lgam) 



Zinc i 

 am'lgam \ 



Saturated solution of 

 CdS04 



Saturated solution 

 ZnS04 



0,5 



Mercury. 

 Depolarizer: paste 

 of Hg2S04 and 

 CdS04 . . . 



Mercury. 

 Depolarizer: paste 

 of Hg2S04 and 

 ZnS04 . . . 



1. 01 83* 

 at 20° C 



i-434t 

 at 15° C 



(d) Secondary Cells. 



Lead accumulator 



Regnier (i) . • . 

 (2). . . 



Main . 

 Edison 



Lead 



Copper . 



Amal. zinc 

 Amal.zinc 



Iron . . 



H2SO4 solution of ) 

 density i.i . . . ) 



CUSO4 -f H2SO4 . . 



ZnS04 solution . . . 

 H2SO4 density ab't i.i 



KOH 20 % solution . 



PbOo 



" in H2SO4 

 A nickel oxide 



of full 

 discharge. 



- * E. M. F. hitherto used at Bureau of Standards. See p. 251. The temperature formula is Et^ E20 — 0.0000406 

 (t — 20) — 0.00000095 (t— 20)2 -f-o.oooooooi (t— 20)2. tThe value given is that adopted by the Chicago International 

 Electrical Congress in 1893. The temperature formula is Et= Eij — o.ooug (t— 15) — 0.000007 (t— 15)*. 



t F. Streiuti gives the following value of the temperature variation — at different stages of charge : 



dt 

 E. M. F. 1.9223 1.9828 2.0031 2.0084 2.0105 2.0779 2.2070 



dE/dtXio6 140 22S 335 285 255 S30 73 



Dolezalek gives the following relation between E. M. F and acid concentration : 

 Per cent H2SO4 64.5 52.2 35.3 21.4 5.2 

 E.M.F., o°C 2.37 2.25 2.10 2.00 1.89 



Smithsonian Tables. 



