290 VOLTAIC ELECTRICITY. SECT. XXIX. 



SECTION XXIX. 



Voltaic Electricity The Voltaic Battery Intensity Quantity Compari- 

 son of the Electricity of Tension with Electricity in Motion Luminous 

 Effects Decomposition of Water Formation of. Crystals by Voltaic 

 Electricity Electrical Fish. 



VOLTAIC electricity is of that peculiar kind which is 

 elicited by the force of chemical action. It is connected 

 with one of the most brilliant periods of British science, 

 from the splendid discoveries to which it led Sir Hum- 

 phry Davy ; and it has acquired additional interest 

 since the discovery of the reciprocal action of Voltaic 

 and magnetic currents, which has proved that magnetism 

 is only an effect of electricity, and that it has no existence 

 as a distinct or separate principle. Consequently Voltaic 

 electricity, as immediately connected with the theory of 

 the earth and planets, forms a part of the physical ac- 

 count of their nature. 



In 1790, while Galvani, Professor of Anatomy in Bo- 

 logna, was making experiments on electricity, he was 

 surprised to see convulsive motions in the limbs of a 

 dead frog accidentally lying near the machine during an 

 electrical discharge. Though a similar action had been 

 noticed long before his time, he was so much struck with 

 this singular phenomenon, that he examined all the cir- 

 cumstances carefully, and at length found that convulsions 

 take place when the nerve and muscle of a frog are con- 

 nected by a metallic conductor. This excited the atten- 

 tion of all Europe ; and it was not long before Professor 

 Volta of Pavia showed that the mere contact of different 

 bodies is sufficient to disturb electrical equilibrium, and 

 that a current of electricity flows in one direction through 

 a circuit of three conducting substances. From this he 

 was led, by acute reasoning and experiment, to the con- 

 struction of the Voltaic pile, which, in its early form, 

 consisted of alternate discs of zinc and copper, separated 

 by pieces of wet cloth, the extremities being connected 

 by wires. This simple apparatus, perhaps the most 

 wonderful instrument that has been invented by the in- 

 genuity of man, by divesting electricity of its sudden and 



