492 Voltaic Circles produced by Acid and Alkaline Fluids. 



Metal used. 



Alkaline fluid. 



Time. 



Milligrams 

 of silver 

 precipi- 

 tated in 



voltameter. 



Hydrogen liberated in 

 cubic centimetres at 

 0° C. and 760 mm. 



Equivalent 

 to silver 

 deposited 



Tin 



)j 



Lead .... 

 Copper . . 



>> • • 



?> • • 

 Silver . . . 

 Mercury . , 

 Palladium 

 Grold .... 

 Nickel 

 Cobalt 



Caustic soda. 



Ammonia. 

 ' Potassium 



cyanide 

 and caustic 



potash. 



3 hrs. 



2 „ 

 16 „ 

 42 „ 



10 , k 



24 

 18 

 11 

 18 

 4 



107 

 137 

 244 

 11 



120 



115 

 69 

 78 

 106 

 141 

 45 

 15 



11-08 

 14-2 

 25-3 

 1*14 



12 '4 



11-9 



7- 15 



8- 08 

 11 

 14 6 



4-7 

 1-56 



In all the cells examined, the ultimate action may be expressed by 

 the scheme — 



f X | H 3 S0 4 | Na 3 S0 4 | 2NaOH 

 lXH 3 | S0 4 lSra 3 | S0 4 Na 3 | H 3 + 0, 



where oxygen is evolved, X being some substance capable of com- 

 bining with hydrogen (nitric acid, chromic anhydride, chlorine, &c.) ; 

 and by the scheme — 



f H 3 S0 4 | Na 3 S0 4 | 2NaOH | Y 

 lH 3 I S0 4 Na 3 | S0 4 ]STa 3 | H 3 + OY, 



where Y is some substance capable of uniting with oxygen (pyro- 

 gallol, ferrous oxide, copper, gold, &c). For every gram- equivalent 

 of silver thrown down in the voltameter, consequently, a gram- 

 equivalent of both acid and alkali must disappear by mutual neutra- 

 lisation daring the passage of the current. This disappearance was 

 verified quantitatively by titration in various experiments with no 

 more lack of precision than the nature of the observation would lead 

 one to anticipate. 



We find that by combining two fluids, one alkaline and containing 

 a powerful reducing agent, the other acid and containing an energetic 

 oxidiser, with platinum plates immersed in each {e.g., caustic soda 

 solution of pyrogallol, and sulphuric acid solution of chromic anhy- 



