concerned in the Phcenomena of ordinary Electricity, fyc. 345 



will suffice. In all cases the mixtures of acid and water were 

 allowed to stand for twenty-four hours before using them, in 

 order to guard against unequal temperature. 



It may be premised that, independently of any objections now 

 to be made, the law as laid down by Faraday is obnoxious to 

 this objection, that if of several separate quantities of electricity 

 the smallest be adequate to produce a deflection of 90°, all the 

 greater quantities will be erroneously indicated by the same 

 degree. 



Experiment 1. — With two ounces by measure of acid, consist- 

 ing of equal weights of concentrated sulphuric acid and water ; 

 the zinc plate newly amalgamated. 



The needle settled at 

 In 1 minute it fell to 

 In 8' rose to . 

 In 20' rose to 

 In 32' rose to 

 In 48' fell to . 

 In 51' fell to . 

 In 53' fell to . 

 In 55' fell to . 

 In 60' fell to . 

 In 63' fell to . 

 In 65' fell to . 

 In 68' fell to . 



69° 



68° 

 681° 



n s 



72° 



71° 



70° 



68° 



66±° 



66 3 



65° 



64° 



63° 



At this moment the solution of the zinc was completed, and 

 the needle immediately sunk. Thus the exposed zinc was dissolved 

 away in sixty-eight minutes. 



Experiment 2. — With two ounces measure of acid, consisting 

 of one part of concentrated sulphuric acid and five of water, both 

 by weight ; zinc newly amalgamated. 



The solution of the zinc was now completed; the portion 

 which had been exposed to the action of the acid was dissolved 

 away in 5£ hours nearly. 



It appears that the same quantity of zinc was dissolved in the 

 first experiment in 68 minutes, and in the second in 5} 2 hours; 



