376 Miscellanies. 



But it is obvious that this experiment affords another argument still 

 in favor of the conjoined influence of the two generally assigned caus- 

 es as held by Berzelius. For if, when the arch of metal is of copper 

 alone, the electricity is of small intensity, and yet, without any addi- 

 tion to the apparent chemical action, becomes of greater intensity by 

 merely replacing a portion of the copper by a wire of zinc, it is evi- 

 dent that the circumstance of centact has an influence, if not in the 

 primary developement of the electricity, at least in making it sensi- 

 ble. Or if the action of the nitric acid vipon the copper appear to in- 

 crease by making the arch in part of both metals, Avhile at the same 

 time the electrical intensity is increased, it might even be presumed that 

 the contact of the two metals influences the primary developement 

 itself of the electricit)^ At all events, it does seem, both from this 

 experiment, and from the phenomena of the compound piles describ- 

 ed by Berzelius in his Larbok, which De La Rive has endeavored, 

 though unsatisfactorily, to explain, according to his own views, that 

 at present we cannot entirely account for all the appearances of bodies 

 influenced by galvanic electricity, by either of the theories taken 

 alone. 



Watkins has carried the simplicity of this combination of De La 

 Rive still further. He has succeeded in forming a pile of perceptible 

 tension, with plates of zinc alone, polished on the one side, and rough 

 on the other, without any moist conductor. They are placed in a 

 wooden frame, parallel to each other, at a distance of one or two mil- 

 limetres, so as to have a thin layer of air between each. The com- 

 bination is, air, rough zinc, smooth zinc, air, &c. and the rough zinc 

 is'positive, as when the place of air is supplied by a liquid. This has 

 been explained like De Luc's pile, by the oxidizing affect of the air ; 

 but it is difficult to conceive that such arrangements can owe their 

 polarity to any chemical action upon the metallic surfaces, since Ber- 

 zelius, in commenting upon this opinion of Davy, in his Arsberattelse 

 for 1827, states, that he has kept a pile formed of brass and tin pa- 

 pers, in which the tin is the positive metal, in activity for eight years, 

 and yet the tin paper remained to the last, as pure and brilliant as 

 when first employed. And that the moisture of the paper Avhich was 

 supposed to be instrumental in causing oxidation, has no connection 

 with the electro-motive agency, has been long ago shown by the ex- 

 periments of Jager, in whose piles the papers were dried and sealed 

 up with a non-conducting body, at the temperature of 140° Fahr., so 

 as to be air-tight, and yet continued in activity. These phenomena 

 cannot be explained without having recourse to something more than 

 chemical action, " which seems by no means necessary for the de- 

 velopement of the electrical elements in the dry pile. The absence 



