Soine Account of Electrical Experiments. 261 



tlie axis of the tube, and with a small interval between them at 

 its centre, so as to form an interrupted metallic circuit in water. 

 The tube 1, is placed between the conductor of an electrical 

 machine and the knob of an insulated jar C, and the tube 2, 

 between the outside of the same jar and the ground. The jar 

 is provided with a Lane's electrometer, which occasions a dis- 

 charge regularly at a certain number of turns of the machine. 

 Now, according to the Franklinian theory, the jar can only be 

 charged under these circumstances by electricitv passing through 

 ihe tube 1 from A to B, to the knob of the jar; and through 



the tube 2, also from A to B in its course from the outside of 

 the jar to the earth. M. De Nelis found that by repeated charges 

 of the small jar for four or five hours, the' wire A in each tube 

 became oxidated, and the oxide produced was also in each tube 

 attracted by the wire B. By reversing the tubes at the end of 

 the experiment, and proceeding with the charges, these effects 

 were precisely reversed, as is the case when the same manipula- 

 tion is employed with tiie Voltaic apparatus. From this he con- 

 cludes, that the phsenomena of electricity are produced by a 

 single current, but at the same time ol)jects to Franklin's theory 

 ill explanation of them. The indications of this experiment are 

 very analogous to many of those usually employed in illustration 

 of the Leyden jar; but it exhibits more decisively tlie identity 

 of the signs evinced by the outside of an insidatcd jar during the 

 process of charging, with those of the conductor by which the 

 jar is charged; and it shows at the same time tliat the electrical 

 niachine,as well as the Voltaic app:uatus, produces very oppo- 



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