346 On the Constitution of the Electric Fluid. 



hence, averaging both, the quantity of electricity* that passed 

 in every instant of time in the first case was five times greater 

 than in the second; yet the deflections were scarcely different, 

 far from being in the direct ratio of the quantity of electricity 

 that was passing at any moment. 



The next two experiments were made with unamalgamated 

 zinc, but were iu all other respects the same as the former. 



Exp. 1. — With two ounces measure of acid, consisting of equal 

 parts of concentrated sulphuric acid and water, both by weight. 



The needle settled at . . 67° 



In 7 minutes it fell to . . 65° 



In 17' fell to 62° 



In 24' fell to 61° 



In 32' fell to 59° 



Thus the zinc was dissolved in 33 minutes. 



Exp. 2. — With two ounces measure of acid, consisting of one 

 part of acid and five of water, both by weight. 



The needle settled at . . 66° 



In 6 minutes it fell to . . 64° 



In 7' fell to 62° 



In 9' fell to 60° 



In 10' fell to 59° 



In 11' fell to 57° 



In 13' fell to 55° 



The zinc was dissolved in 13 minutes; that is, in the first 

 case the quantity of electricity that passed in every moment of 

 time was two and a half times greater than that which passed in 

 the second. 



I repeated these experiments to the number of forty, with 

 different acids, and different strengths of the same acid. All of 

 them pretty nearly coincided in proving the general proposition, 

 that notwithstanding the great difference in the quantities of 

 electricity, which, according to the law in question, must have 

 passed at any instant of time during the solution of the zinc, 

 the deflections were as nearly the same as could be expected in 

 cases of such delicacy, especially when the variations of electro- 

 motive power incidental to milled zinc are taken into accountf. 



When the experiments were made with very weak acids, the 

 galvanometer needle fell soon and rapidly, the cause of which I 



* "The quantity of electricity is dependent upon the quantity of zinc 

 oxidized." — Faraday's Researches, par. 919. 



" The electricity of the voltaic pile is proportionate in its quantity to the 

 quantity of matter which has been chemically active during its evolution." 

 — Ibid. par. 916. 



t Binks, Philosophical Magazine, N. S. vol. xi. p. 75. 



