402 M. Matteucci on t/ie Electricity of Flame. 



If I plunge the two ends of platinum wire into distilled water at 

 the same time, the needle seldom remains at zero, but generally 

 after a deflection of a few degrees returns to zero, the circuit 

 having been left closed. If I then withdraw the two wires 

 simultaneously from the water, and after some minutes plunge 

 them again into the water, there is no deflection of the needle. 

 The same result is obtained if the two wires are wiped dry with 

 linen or paper before replacing them in the water. I have suc- 

 ceeded in obtaining very strong and constant currents in the 

 following way : if one of the wires is moved rapidly in the liquid, 

 if this wire alone is withdrawn from the water and after some time 

 replaced, if the wire is wiped and rubbed with linen or paper andthen 

 put into the liquid, if, finally, this wire has been heated over char- 

 coal, — in all these cases there is a strong current on closing the 

 circuit, and the direction of this current shows that the wire 

 which has undergone these changes becomes as the zinc of the 

 voltaic bittery. It is easy to show, as may be done with pla- 

 tinum plates which give secondary polarities, that these currents 

 exist only in presence of the liquid interposed between the two 

 platinum wires. In order to prove this, we have only to with- 

 draw the two wires from the water, and then to heat or rub one 

 wire more than the other; if then this wire is plunged into 

 mercury, no current is obtained, whereas by employing water a 

 current is obtained. In order to explain these results, we must 

 admit with M. De la Rive, that platinum decomposes, or tends 

 to decompose water at the ordinary temperature, and we may 

 suppose that this tendency is increased by the circumstances 

 which I have described. 



I will now give, in the last place, the experiment which serves 

 to explain the production of electricity by flame. I place two 

 platinum wires so that one is in contact with the centre of a flame 

 of a spirit-lamp, and the other with the outer margin or apex of 

 this flame. I make the experiment as before described, and the 

 needle, as we already know, deflects so as to indicate a current 

 the direction of which is from the base towards the apex of the 

 flame. After a certain time I take away the flame, I leave the 

 wires to cool, and close the circuit with water. I have then a 

 strong current in the same direction as when I employed the 

 flame. It is hardly necessary to tell you that I assured myself 

 of the truth of this result by alternating the position of the two 

 platinum wires in regard to the flame, as well as by holding the 

 two wires at the same level in the flame, in which case no current 

 is obtained either with flame or with water. I have also ascer- 

 tained in this experiment, that when the two wires, after being 

 kept in the flame, are put into mercury, no current is obtained, 

 whereas when they are plunged into water there is a strong current. 

 • I do not therefore hesitate to conclude, that the electric current 



