3£Q NEW CLASSES 0* GAETANIC CONDUCTORS. 



design is consumed on the positive side by the chemical 

 action of the pile, without exhibiting the slightest trace of 

 oxidation. Besides, the wires most easily oxided show no 

 appearance of oxidation, when they have been employed 

 to establish a communication between the positive pole and 

 a prism of soap perfectly dry. 

 The water must An experiment of importance on other accounts shows, 

 •wnh thaVosi- ^ a * * ne wa te r must be applied to the precise point where 

 tive wire, the positive wire touches the soap, in order that the positive 



effect may be propagated as well as the negative. Let A B, 

 Plate IX. Fig. 6. be two prisms of soap perfectly dry. 

 Into each introduce one of the polar wires of the pile, and 

 then connect them together by a wire C, forming an arc 

 from one to the other. The electrometers of the pile will 

 indicate a complete insulation of the positive pole ; the con- 

 tact with water of either of the two prisms, or of the in- 

 termediary arc C, will constantly discharge the negative 

 electrometer, and carry the positive to a maximum of di- 

 Tergence. If now a wet conductor be applied between the 

 wire of the positWe pole, and the prism A, into which it 

 is inserted, the electrometer will indicate, that the prism, 

 and likewise the whole of the intermediate arc C, belong 

 to the positive pole; since on touching these parts of the 

 apparatus the electrometer of the negative pole is made to 

 diverge, and the positive side is discharged. But the 

 prism B belongs wholly to the negative pole, and on 

 touching it divergences are produced the reverse of those 

 that occur on touching A* The circle therefore is not 

 completed : and in fact, if an apparatus for decomposing 

 water be interposed, no chemical effect takes place; while 

 on touching the two prisms at the same time a shock is 

 felt, if the fingers have been wetted, and the pile has a 

 certain degree of energy. In all cases the simultaneous 

 contact of the two prisms excites in a prepared frog very 

 strong contractions. But all these effects, which depend 

 ton the insulation of the positive pole, cease, and instead of 

 them gas is produced in the interposed apparatus, the mo- 

 ment a second wet conductor is applied to the point where 

 the intermediate arc C touches the prism B, because it is 

 at this point, that the arc C exhibits the positiv* effect. 



* 14 



