28 HISTORY OF GALVANISM. 



in the body Mr. Nicholson observed, that the same process 

 e * of the decomposition of water is carried on in the 

 body of the pile, as between the two ends of the 

 wire in the interrupted circuit ; the side of the 

 zinc next to the fluid being covered with oxide 

 in two or three days, and the apparatus then ceas- 

 ing to act. It was also observed, that the com- 

 mon salt which had been dissolved in the water 

 was dissolved, for that there was an efflorescence 

 of soda round the margin of the plates. Mr. 

 Nicholson afterwards found that, by using me- 

 tallic plates of considerably more extensive surface, 

 no greater effect was produced in the decomposition 

 of water, or in the violence of the shock ; so that 

 he concludes, " the repetition of the series is of 

 more consequence to this action than the enlarge- 

 ment of the surface." As he proceeded in his ex- 

 periments it was more decidedly ascertained, that 

 the electricity of the silver end was negative, that 

 of the zinc end positive. Although it appeared 

 evident that there had been a decomposition of 

 water effected by the copper wire, yet Mr. Nichol- 

 son determined to render the operation more deci- 

 sive, by employing a metal which was not oxida- 

 Piatina ble. Platina was therefore substituted for the 

 dnced P both c PP er > an( i now g as was disengaged from both 

 hydrogen s id es an d neither of the wires were tarnished. 



and oxy- 

 gen. In a subsequent experiment, the w^ires were so ma- 

 naged, that the gases extricated from each side 

 were kept distinct ; and it was found that they 

 consisted, the one of oxygen, and the other of hy- 



2 



