an Gases to the Contact Potential Series. 
end of the series. 
desalis: 
397 
In hydrogen, then, our hypothesis con- 
cerning the cathode series is supported by the experimental 
Copper, tested in two other series of observations 
not here recorded, fell consistently between silver and nickel 
in both eases. 
TABLE IT.—Cathode-Fall. 
Metals compared. Current 1:0 maa. 
| | | ) i | | | | 
is ' | / | | | 
Gas. | bros | Pt.|Ag.| Au. | Cu.| Fe, | Ni.) Bi. | Sb. | Sn.| Pb. | Ca.| Zn. | AL. | Mg. 
i | E92 ES SO (Se le 
2:03 |899| 406 | 386 |......|...... BO usin 389 | 382 359 | 326 | 269 266 
Hydrogen. | 2°01 | 392/398) 361/......|...... ES ener eee | 372 | 366 | 363 | 326 | 255 251 
£00 4373 (Se0e ls Cold eee eee [378 375/375 |824| 252 | 255 
. 1:23. | 252/958 | 258 | 258/255 937 |......|...... ‘ues. 243 266 | 265 | 217. 
Nitrogen. | 1-25 | 260/264/ 264| 264/96 | 2943 (0000/07 |... 240 | 270 | 271 | 219 | 
IDA) 258, 263) te. 262 nad ae 954| 255 |...... ST eaters 219 228 
1-21 | 362 | 371 | 364 | 350| 339/......| 364 |......|..... | 870 | 349] 347|302| | 
Oxygen. | 1:20 | 356 | 367 | 358 | 353 | 336|....../ 357)... 370 346 | 345 301 | 
1:20 | 360 ...... 361 | 354 839 Sane 358 360|....../848]..... | 305 | hoe 
i ules | ial 
Tasie ITI.—Anode-Fall. Metals compared. 
i . | | | 1 | : i | | 
Gas. Gas- | pt.| Ag.| Au.|Cu.| Fe.| Ni.| Bi. Sb. Sn.| Pb. | Cd.) Zn. Al. 
press. | | ) | | 
173 | 180| 18-4 20-1] 189/221... 199 20°6) 20°3)....../ 20-7) 20-4 
Hydrogen. | 1-71 | 18-4| 18'8| 19°5| 19-7] 18°5] 19°9).............|...--- 20°3)......, 20-2 20-1 
170 179/177 207 200)...... 193 180.....- 200)..... 199) 191 197 
ae 7439 |1g¢| 19-41] 21-11 19-7| 19-7/208).................. 20:6 19:7) 19°6 22-9 
itrogen. 1:37 | 18:5 186 19°9] 190} 194/194... | 20°0 19:1] 18:5 21:9 
G@eyeen. 1:20 |922]...... Es 3 23-9 93-8 93-5)...... 23° QD... WD... 93-9 
The Anode Fall.—Three similar sets of observations of the 
anode-fall in hydrogen are recorded in Table III. 
The 
fall 
for most metals remaining very constant under the action of 
the current, it was measured more deliberately than the 
cathode-fall as a mean of the “right ” and “ left”? deflexions 
‘of the electrometer-needle. 
anode series to be the reverse of that of the cathode; 
the reverse potential series. 
while it is low in the cathode series. 
Here we find in general the 
that is, 
Gold, however, is high here, 
The values for steel 
fluctuate considerably, and for magnesium the anode-fall for 
all gases increases so rapidly with use that it was impossible 
to obtain a reliable value for it. 
The Electrode Fall in Nitrogen and Oxygen—In Table I. 
