646 M. W. HankePs Account of some Experiments 



The investigation of these currents by means of the galvano- 

 meter carries along with it the doubt, as to whether the increase 

 of the angle is due to an increase of the electric tension between 

 the diflferent parts of the flame from which the electric fluid is 

 conducted, or to a diminution of the resistance within the flame. 

 It is therefore necessary to separate these quantities. This sepa- 

 ration is generally effected by the introduction of other known 

 resistances. To obtain a general notion of the electric tension 

 of the different portions of the flame, I have resorted to a some- 

 what shorter method, which consists in introducing the current 

 caused by the flame into a circuit in which another current of 

 known value circulates. Heretofore the circuit was composed 

 of the flame, the connecting wires and the galvanometer ; into 

 this I now introduced a bit of zinc and copper which dipped into 

 a vessel of water. Let this aiTangement of zinc and copper be 

 called an element. By means of the commutator, the current 

 developed by this element might be transmitted in the same 

 direction as the current due to the flame, or in an opposite direc- 

 tion. I will name the side to which the flame-current causes 

 the needle to move the positive side, and the opposite side the 

 negative. 



When the lamp No. 1 was so regulated that its flame did not 

 quite reach the top of the chimney, and the platinum foil held at 

 a small distance above the latter in the inclined position already 

 mentioned, before the zinc and copper element was introduced 

 the angle due to the flame-current was not quite 10°. By intro- 

 ducing the element so that its current moved in the same direc- 

 tion as that proceeding from the flame, the angle increased some 

 degrees ; when the direction was reversed, the needle went back 

 to 5°. A similar result was observed when the chimney was 

 taken away and the flame increased at pleasure. In the case of 

 lamp No. 2, when the chimney was removed and the bellows set 

 in action, the position of the needle indicated that the direction 

 of the current was the same as before ; thus compelling the in- 

 ference that the electro-motive force of the flame (the electric 

 difference between its top and bottom) is greater than the electro- 

 motive force of the zinc and copper element. When, however, 

 two such elements were introduced, and the current which they 

 originated was directed against that proceeding from the flame, 

 the latter was overcome and the needle moved to the negative 

 side. 



The deviations of the needle were different when the chimneys 

 were set upon the lamps. When the lamp No. 1 had its chim- 

 ney set on, the current of a single element was unable to com- 

 pete with the flame-current as long as the luminous portion of 

 the flame did not reach the full height of the chimney. When, 



