Prof. Majocchi oti the Origin of the Voltaic Cwrent. 99 



of Volta there is no chemical decomposition, there being no 

 intermediate electrolyte ; and thence an electrical disturb- 

 ance only is shown, an electricity of tension, which to be 

 formed into a current requires the circuit to be completed 

 with a liquid. For if this liquid does not exert any che- 

 mical action in any of the metals placed in contact, then no 

 current is manifested on the galvanometer. Gold and plati- 

 num show an electrical disturljance on the condenser, but no 

 current when they are immersed in nitric acid, and united with 

 one another metallically by means of the wire of the galvano- 

 meter. But if some drops of hydrochloric acid are added 

 to the nitric acid, the gold only is attacked, and immediately 

 an electric current is manifested on the galvanometer. In 

 the chemical action of the acid upon gold or on the zinc 

 of the common voltaic pair, electricity is evolved ; or this 

 fluid, by virtue of that force, is separated and set free from the 

 ponderable molecules which undergo a decomposition to form 

 a new compound, and the adhesion between the two bodies in 

 contact, which would produce a simple electrical disturbance, 

 gives the discharge and determines the course in which the 

 current of the fluid is directed precisely according to the che- 

 mical action. In the circuit of the battery between every pair, 

 where the electricity is simply disturbed and would show only 

 a tension, an electrolyte is placed, which is decomposed by the 

 afiinity which one of the metals of the pair exerts upon it : by 

 this decomposition the electricity of the ponderable matter is 

 developed and becomes free, and is emitted from the electro- 

 negative metal into that of the electro-positive. This discharge 

 proceeds from one pair to another, and the electric fluid set 

 free by the chemical action is put into a continuous current 

 along the circuit. From the firot experiments of Volta, and 

 from those which have been since instituted in various ways, it 

 is known that the chemical action alone occasions a develop- 

 ment of electricity, and a second force is necessary to put this 

 fluid in motion. Moreover we know that, if this chemical 

 action is impeded without taking away the conductibility from 

 tlie circuit, the current is weakened, and is sometimes in the 

 end entirely destroyed, not being perceptible by the most deli- 

 cate galvanometers. In a voltaic circuit, where two platinum 

 electrodes are interposed, immersed at a distance from each 

 other in acidulated water, the hydrogen gas is deposited upon 

 one of these, polarizes it, and generates a contrary current, 

 which weakens or annuls the primary current, because, whilst 

 the chemical action evolving the electric fluid still exists in the 

 pairs of the pile, there is o|)posed to the impelling force, by 

 which the current is determined, another contrary one, arising 



