Mr R. Adie's Account of Electrical Experiments. 329 



zinc surface becomes partially oxidized, from the greater activity of 

 local action, to which the whole of the absorption of oxygen beside 

 the zinc plate is due. Amalgamating with mercury did not reduce 

 the local action. Where the zinc remains for days untouched, the mer- 

 cury lodges at the lower extremity, and thus an active couple is 

 formed. Copper and platina plates under tubes of oxygen gave 

 like results with much slower rates of action. 



A piece of zinc was next cut into two halves, and connected in 

 the usual manner with a long wire galvanometer, the helix contain- 

 ing 2000 convolutions. The two plates of zinc were immersed in 

 water, and arranged to allow a tube containing oxygen to be placed 

 at pleasure over the upper portion of either plate. After complet- 

 ing the connections, a short time was allowed for the galvanometer 

 to reach zero ; the tube filled with oxygen was then inverted over 

 one of the plates which immediately deflected the galvanometer, 

 shewing the oxygenated zinc to he the negative element of the 

 couple. The tube was now passed over from the negative zinc to 

 the positive piece, when, in the course of a few minutes, the galva- 

 nometer again shewed the new oxygenated zinc to be acting the part 

 of a negative or platinode plate. The deflections of the needles were 

 from 15° to 20°, where they remained steadily for some time. In- 

 stead of placing a tube of oxygen over one of the plates, if the water 

 in front of one be stirred carefully with a quill, or if the plate be 

 attached to an elastic wire, and made to vibrate in the water, it is 

 immediately oxygenated more rapidly than the opposite one, and 

 becomes strono-ly negative. The vibrated plate forms a very beau- 

 tiful experiment. Like results were obtained with two pieces of 

 iron. These experiments can all be readily explained, by referring 

 to the gas battery of Professor Grove, where, in every step the ac- 

 tion corresponds to the water battery, all the oxygen in the gas 

 battery is taken up on the negative side, and oxygen placed in the 

 tube beside the hydrogen, developes local action ; so also in the water 

 battery, oxygen supplied to the positive plate impedes the action, — a 

 result which at first sight seemed to me very unexpected. 



In considering the action of oxygen absorbing batteries, I have 

 often felt a difliculty to satisfy myself what was the electrolite de- 

 composed by the galvanic current in its passage from plate to plate. 

 The received opinion is, that water is decomposed. A friend of 

 mine, to whose views I attach value, on considering the results given 

 above, came to the conclusion, that in the action of these couples, 

 water was composed by the negative plate, at the same instant that 

 an atom of oxygen combines with the metal or hydrogen of the po- 

 sitive plate. For my part, I can see no adequate force in couples 

 of two pieces of zinc, or two pieces of iron to eflfect the union or dis- 

 union of the elements of water. The peroxide of hydrogen, a very 

 much more easily decomposed body than water, according to Dr 

 Turner's Chemistry, 7tli edition, page 201 , is not decomposed by iron ; 



