DOVE ON THE ELECTRICITY OF INDUCTION. 105 



of a current and its chemical action, we may consider it proved 

 by the experiments of Pouillet*, Jacobif, and Weber J, which 

 directly confirm Faraday's law for constant electrolytic action, 

 that with electric currents produced by galvanic means, the 

 decomposition of water in a given time is proportional to the 

 constant power of these currents as it is indicated by the mul- 

 tiplier § during that time. From two currents therefore, which 

 are known to be galvanometrically equal, we may expect an 

 equal amount of chemical action. 



In the phsenomena of induction, up to the present time, the 

 cause of an increased physiological action has been ascribed to 

 a larger quantity of electricity in motion which produced it, and 

 hence it has been indirectly assumed, that in magneto-electric 

 currents the physiological action is proportional to the deflection 

 of the needle of the galvanometer, and to the volumes of the 

 gases in the voltameters. With the electricity of the electric 

 machine, a difference has long been observed in this respect ; for 

 the discharge of a Leyden jar, which will communicate a power- 

 ful shock to the human body, is not capable of deflecting the 

 magnetic needle, and only acquires the power of doing so when 

 a wet string is interposed in the connecting circuit, and its resist- 

 ance to conduction is thus increased. When this is done the 

 physiological action decreases in a remarkable manner, whilst 

 the dazzling white light of the spark is changed to a yellowish- 

 red colour. The shock is as completely prevented when the one 

 coating of the jar is held in the hand and a point which is lu- 

 minous with a bluish light in the dark is gradually approached 

 to the other, or, as Lord Mahon states, when the jar is dis- 

 charged by a piece of ivory. In this case of gradual discharge 

 by the approach of a point, there occurs, as Colladon first 

 showed II, an action upon the magnetic needle. Suppose the 

 electricity of both coatings were divided between two electro- 

 meters, of which the leaves of the one diverged as many degrees 

 positively as those of the other diverged negatively, then, if both 

 were connected by a conductor when the leaves slowly collapsed, 



* Comples Rendus, v. p. 78o. 



+ liuUclin S'cietitifique de rjcadhnie de Sf. Pefersboiirg, 1S39, j). 354. 



J RrsiiJlate des Magnet. Vereins, 1840, p. 90. 



§ Whether it be a sinus compass, or a tangent compass, or a coil of wire 

 suspended in the manner of a bifilar magnetometer and directed by tiio ter- 

 restrial magnetism. 



II .innales de Chimie et de Physiqur, xx.xiii. p. (V2. 



