THEORY OF TENSION OF THE VOLTAIC BATTERY. 



83 



passes both the primary and secondary wire is also doubled : the ratio - is therefore 



a 



the same as before. For this reason, increasing the magnitude of the plates increases 

 the quantity only, and not the tension. 



295. Under all these circumstances, therefore, the tension depends on the ratio of 

 the quantity that does pass the combination, to the quantity that the system tends to 

 put in motion. 



296. Before, however, we can go farther in the study of these conditions of tension, 

 or attempt to show that the arrangement of Volta, and a single pair under the influence 

 of a long or thin wire, are, in point of fact, alike in principle, it is necessary that we 

 should understand the nature of the different disturbing actions that may arise in the 

 generating cells of the electromotor. 



296. I took a zinc plate 7 inches long and 3 wide, and a corresponding copper : 

 the surface of the former was amalgamated and the latter brightened. The plates were 

 fixed at an immovable distance from each other, and immersed in a jar containing 34 

 ounces of water. SULPHURIC ACID was then added by half drachms successively. 



TABLE E. 



298. Here we have an exemplification of the converse of the fact already so much 

 insisted on. As the quantity developed from the same surface gradually became greater 

 and greater, the tension became less and less, due to the increased conducting powers 

 of the fluid medium. It is the same effect that would have been produced by constant- 

 ly shortening the connecting wire. 



299. Such is the action of increasing doses of sulphuric acid ; let us now see how 

 NITRIC ACID will act. The copper plate being repolished, and the zinc reamalgamated, 

 and everything else being as at the commencement of the former trial, the latter acid 

 was now added to the cell in the same way that the former had been used. 



TABLE F. 



These measures are effected with some difficulty, as the acid acts somewhat irregu- 

 larly, and keeps the needle vibrating. 



