Effects of the Contact of Flames and Metals. 407 



electric effects only in the contact of the metals with each 

 other, and in that of liquids with the metals and salifiable 

 bases, even when this contact was followed by a chemical ac- 

 tion. It has also been shown, that in a circuit formed of two 

 parts of the same metal, if one of them were made red-hot 

 near the points of fusion, an electric current would be esta- 

 blished in the entire circuit, when it was closed, of such a kind 

 that the side which was not heated would furnish positive 

 electricity, and the other negative electricity. It has been 

 found also, that the electricity developed in this phaenomenon 

 had not sufficient tension to be rendered sensible with a con- 

 denser. 



We are at present about to occupy ourselves with another 

 class of phaenomena. Instead of taking a circuit either wholly 

 metallic, or of metals in contact with any liquids what- 

 ever, we shall substitute for these last, inflamed gases, and 

 we shall observe the phaenomena which will be then pro- 

 duced. The flames which we shall submit to experiment are 

 those which proceed from the combustion of alcohol, of hy- 

 drogen gas, or of a sheet of paper. 



Let us place on the capsule of wood or of earthenware which 

 communicates with one of the plates of the condenser, a wire 

 of platinum, or a plate of the same metal of a decimetre in 

 length, and which projects beyond the edge of the plate; let 

 us put the lower plate in communication with the ground ; let 

 us plunge one of the extremities of the wire or of the plate in 

 one of the flames of which we have just spoken : — if the metal 

 attains the red temperature, it will take negative electricity; in 

 the contrary case, it will acquire positive electricity. In these 

 two circumstances the flame will always have an electricity 

 opposite to that of the metal. To collect that which the flame 

 takes, abit of moistened wood is passed upon the capsule,which, 

 not experiencing any combustion, performs the office of a 

 conductor, and transmits to the condenser the electricity which 

 it has taken from the flame. 



A copper wire gives a similar result. In general, it ap- 

 pears that all metals possess more or less of the property which 

 we have just observed in platinum and in copper. Thus, a 

 metal plunged in a flame fed by a current of hydrogen gas 

 takes the negative or positive electricity, according as its tem- 

 perature is more or less elevated, and communicates to the 

 (lame the contrary electricity. It now remains to determine 

 tin- temperatures at which these phaenomena are produced in 

 each metal. Now, as the passage from one electric state to 

 another is indicated by the absence of electricity, it follows 



that 



