12 Ml'. G. Gore on the Development of Dynamic Electricity 



copper plate was quite tarnished after the experiment, but the 

 silver one not at all so. These experiments bear the same expla- 

 nations as the preceding ones. With both plates composed of 

 silver, and the same liquid retried, there was a strong upward 

 current, the upper plate alone being tarnished after the expe- 

 riment. 



36. Similar results were obtained by heating pieces of copper 

 foil and platinum foil in V-tubes containing a solution of sul- 

 phate of copper. With hot platinum and cold copper the deflec- 

 tion was 20, the copper of course being positive ; but with hot 

 copper and cold platinum it was only 9. The heat in these two 

 cases was applied by means of a small blowpipe, and was conse- 

 quently much greater and less regular than in the preceding 

 experiments. 



37. In some cases we find the chemical action develope a cur- 

 rent of sufficient force to overpower the cun-cnt due to the other 

 cause and determine it in the opposite direction. For instance, 

 I fitted the apparatus with plates of rolled grain tin, and charged 

 it with a pre-boiled mixture of 4 ounces of distilled water and \ 

 of an ounce of pure hydrochloric acid, and applied heat in the 

 usual manner; the hot plate was positive, and increasingly so 

 with the increase of heat. A few very small bubbles of gas were 

 evolved against the upper plate at the higher temperatures by 

 the chemical action. Retried this experiment with similar results. 

 I also fitted the apparatus with platinum plates, and charged 

 the hour-glass with a mixture of 2 ounces of pure hydrochloric 

 acid and 1 drachm of pure nitric acid, and applied heat as 

 usual ; the hot plate became positive, equal to 27'5 degrees at 

 180° F., the lower plate being at 65° F. The experiment was 

 interrupted by the evolution of bubbles of acid vapour against the 

 upper plate. I further tried the same plates with a mixtiu'e of 1 

 drachm of the above liquid and If ounce of pure hydrochloric 

 acid ; the hot plate became positive equal to 59 degrees at 

 208° F., the lower plate being at 64° F. The evolution of gas 

 against the upper plate decreased the amount of deflection at the 

 higher temperatures. In both of these experiments the upper part 

 of the liquid became of a yellow colour (from dissolving of the 

 platinum) at the end of the experiment. 



38. In the following cases, also, the chemico-electric current 

 overpowers the current due to the other cause. I fitted the 

 examiner with plates of antimony (cast with cisterns of the same 

 metal at their backs in place of the separate cisterns of glass or 

 copper), and charged it with a mixture of equal measures of di- 

 stilled water and hydrochloric acid ; the hot plate was positive, 

 and increasingly so by increase of heat. Retried with 4 ounces 

 of distilled water and \ of an ounce of pure hydrochloric acid, 



