10 M. W. G. Hankel on the Electric Deportment 
The nature and intensity of the electrical tension varies with 
the nature of the metal placed in the lamp, as well as with that 
of the metal above it. 
But the nature and intensity of the electrical tension varies 
also with the position of the metal above or in the flame. 
When a thin plate of metal, standing at a considerable height 
above the lamp, is made to approach the latter, so that it gra- 
dually becomes more deeply immersed in the flame and more 
intensely heated, the electricity first observed varies with this 
change of position and becomes more negative; or if at first 
positive, approaches the negative condition more and more. This 
change may amount to more than the electromotive force of an 
element formed of zinc, platinum, and alcohol. 
No change of electric tension, however, takes place with the 
change of position when the metal, on approaching or becoming 
immersed in the flame, is prevented from taking a high tempe- 
rature by ice being placed upon it; or when, instead of a 
metal, a jet of water is passed through the flame. 
Now in my memoir I give positive proof, by means of mea- 
surements, that the electric tensions depend upon the act of 
combustion only in so far as the gases and vapours of which the 
flame consists form a conductor, which, like an ordinary liquid 
conductor, is interposed between the metal situated in or above 
the flame and the alcohol of the lamp. The mere act of com- 
bustion does not produce electricity. 
The electricity observed on the metals situated in or above 
the flame, is nothing more than the tension at the end or pole 
of a galvanic element having the selected metals for the solid, 
and the alcohol together with the heated gases of the flame for 
the liquid conductor. 
The variations in the tensions as the metal gradually ap- 
proaches the flame, are due solely to the increased temperature 
of the metal, and to the consequent change of its position in 
the so-called tension-series. 
All metals by heating are moved towards the positive end of 
the tension-series ; and when the metals are intensely heated, this 
change in place may amount to more than the distance between 
cold zine and cold platinum, alcohol being employed as a liquid 
conductor. For equal degrees of temperature, the amount of 
this change is in all probability not very different in different 
metals. 
If the ends or poles of the galvanic element, formed with 
alcohol and flame as liquid conductors, upon which we formerly 
observed free tensions, are joined together, an electric current is 
produced in consequence of the electromotive power within the 
circuit, whose direction is determined by the above tensions, and 
