#11 IJcItE-OBIedrit I'libersion. 
Bt professor SILVANUS P. THOMSON, B.A., D.Sc. 
J. HE author proposes to give the name of Volta-Electric 
Inversion to a phenomenon which, if not new in every 
detail, is at least new in its generality, because it is, for voltaic 
currents, the precise analogue of the phenomenon of thermo- 
electric inversion discovered by Gumming in the case of thermo- 
electric currents. 
2. Gumming found that the electromotive force of a thermo- 
electric couple (for example, an iron-copper couple) varied not 
only with the relative excess of temperature of the heated 
junction over the temperatures of the rest of the circuit, but 
with the absolute temperature. He found, for example, that in 
an iron-copper pair below a temperature of about 300° G. the 
current through the hotter junction flowed from copper to iron^ 
but that above that temperature it flowed the reverse way, from 
iron to copper. 
3. If a simple voltaic cell be heated, it is well known that 
its current-giving power is altered — generally is improved, but 
sometimes the reverse. Thus the power of a Daniell’s cell 
increases by 1^ per cent, when heated from 0° to 100° G., while 
that of a bichromate cell decreases by no less than 15 per cent, 
under similar circumstances. Such changes arise partly from 
the lessening of the internal resistance and of polarisation, and 
partly from changes in the electromotive force of the cell. In 
investigating recently the change of electromotive force in simple 
