84 



THEORY OF TENSION OF THE VOLTAIC BATTERY. 



300. MURIATIC ACID, under the same conditions and circumstances, being substi- 

 tuted, gave as follows : 



TABLE G. 



301. NITROSULPHURIC ACID, the constituents of which were added alternately in 

 equal measures, was next tried. 



TABLE H. 



302. Solution of SULPHATE of COPPER was next experimented with. 



TABLE I. 



These measures were procured with difficulty, owing to the flocculent deposit which 

 settled on the zinc, more rapidly as the solution was made stronger. 



303. In the general discussion of the measures given by tables E, F, G, H, I, we still 

 see the operation of the same general law, that the tension rapidly diminishes as the 

 acid is added, and that when the same quantity of electricity developed from the same 

 amount of surface by these different acids is presented to the secondary wire, the quan- 

 tities that can pass that wire are very different; and on making use of these different 

 agents, it would appear that they can give rise to currents from the same metalline sur- 

 face, equal in point of quantity, but differing greatly in point of tension, in the follow- 

 ing order, beginning with the most powerful : 



Sulphate of copper, Muriatic acid, 



Nitric acid, Sulphuric acid, 



Nitrosulphuric acid, 



304. Of these bodies, the muriatic acid acts probably in the way that Dr. Faraday 

 has pointed out, but the immediate cause of the rise of tension in the others is to be 

 traced to the circumstance that they furnish oxygen to the nascent hydrogen ; and if the 

 tension of the ordinary current is made to depend on the tendency of the zinc and ox- 

 ygen to unite, it is reasonable to suppose that that tension will increase if a new affin- 

 ity be introduced, the action of which should correspond with and abet that of the zinc 

 for oxygen. This takes place when nitric acid or an oxysalt of easy decomposibility 

 is added to the solution. The tension of the current is not then determined by the af 



