94 Dr. Beetz on the Electromotive Force of Gases. 



c = 0-04'49. 



Although the preceding experiments afford many explana- 

 tions of the action of gas batteries, yet they cannot possibly 

 decide upon the source of the force in them. The solution of 

 this question, however, in my opinion, would constitute nothing 

 less than a final decision as to the nature of electricity of con- 

 tact. In fact, the phaenon'iena which have just been discussed 

 rank perfectly with those which occur in the excitation of a 

 current by solid conductors, with the only difference, that the 

 state of aggregation in the case of the gases may be altered by 

 the solid bodies in contact with them, which is not the case 

 with solid conductors: hence the difference in the absolute 

 values in the case of the forces of the gas batteries, whilst 

 their relative values remain the same. The special activity of 

 the positive gases (as hydrogen) depends solely upon the elec- 

 tromotive force of platinum and hydrogen being far greater 

 than that of platinum and oxygen, or even platinum and chlo- 

 rine; the phsenomenon observed by Matteucci* and others, 

 that small quantities of hydrogen may exceed the action of 

 large quantities of oxygen, then forms a simple analogy with 

 the action of amalgams, in which the positive metal (potas- 

 sium, zinc) preponderates. 



Lastly, regarding the arrangement of the metals and gases 

 in an electromotor series, as given above, we must not deceive 

 ourselves regarding its importance. The metals mentioned 

 (platinum, copper and zinc) hold that position to those gas 

 batteries which contain plates of platinum; in the case of 

 other batteries, their position would be different. Whilst, for 

 instance, zinc is then positive towards hydrogen with a force 

 of 19*68, Bufff found a zinc plate coated with platinum posi- 

 tive towards a polished plate, and subsequently gave a nume- 

 rical value to this tension { ; from this he deduced the conclu- 

 sion, that the position of hydrogen was nearer the positive end 

 of a tension series than zinc, a conclusion which is evidently 



* Comptes Rendus, xvi. p. 846. 



f Annul, der Chem. und Pharm., vol. xli. p. ] 36 ; Archiv. de I'Electr. ii. 

 222. 



I Poggendorff's Annalen, vol. Ixxiii. p. 505. 



