Mr. J. Prideaux on the Theory of Voltaic Action. 217 



square, being each furnished with a copper wire soldered on, 

 the wires 18 inches long, and amalgamated at the further ends; 

 these plates were alternately placed flat on the alkali, the zinc 

 being put in the acid just above the alkaline surface, when the 

 copper was in alkali, and vice versa. 



The following table gives the deflections of the magnetest 

 needle. 



Experiments 

 12 3 4 



Zinc in alkali ... 26° 25 25 26 26 

 Zinc in acid 9 7 8 7 8 



Mean. 



25-5 

 8 



Cur 



17 



4 



The zinc was soon covered with gelatinous white oxide in 

 the alkali ; and the copper in the acid gave off hydrogen gas 

 copiously, but without giving the slightest tinge to the liquor. 



The above table gives only about the average of many ex- 

 periments, some of which differed considerably from the num- 

 bers there given, influenced by the strength and depth of the 

 alkaline solution, of which more (21). 



15. If two glasses be filled with solution of common salt or 

 sulphate of zinc, and connected by a syphon of water ; and a 

 pair of zinc and copper, connected through the multiplier, be 

 plunged one plate in each glass, — divergence of course ensues. 

 Now add some acid to the glass containing the zinc, no in- 

 crease takes place in the divergence. Change the glasses so 

 that the copper shall be in the acidulated one, the divergence 

 is decidedly increased. 



16. In both these cases (14, 15.) we have the zinc and cop- 

 per in metallic connexion through the magnetest, and in 

 liquid communication through the same fluids; the only dif- 

 ference being in the order of arrangements of the liquids. 



Hence the increased effect is not attributable to varied elec- 

 trical relation between the metals ; to different conducting 

 power in the liquid, still less to chemical action, that being 

 greatest when the zinc is in acid, where the voltaic action is 

 least. 



17. At an early period in voltaic history, Mr. De Luc ana- 

 lysed the pile, separating, by interposing a brass wire tripod, 

 one of the members from each group of zinc, copper, wet 

 cloth. His first pile was, silver, tripod, zinc, cloth ; silver, 

 tripod, &c, and this produced all the effects of a good pile; 

 the tripod forming a regular metallic connexion between the 

 zinc and silver, and the wet cloth being in full communication 

 with the other face of each. 



His second pile was, silver, tripod, cloth, zinc ; silver, 

 tripod, cloth, &c, and this produced electrical, but no che- 

 Third Series. Vol. 2. No. 9. March 1S33. 2 F 



