8 Mr. G. Gore on the Development of Dynamic Electricity 



of copper; also interposing between the two instruments two 

 platinum wires 20 inches long each, terminated by two discs, 2| 

 inches wide, of sheet platinum ; heating one of these circles red- 

 hot, and suddenly bringing it in contact over its whole surface 

 with the other and cold one, not the slightest electric current 

 arising from this action passed through the circuit, the liquid 

 completely arresting it. 



21. Contracting the column of liquid to an hour-glass form, 

 either by means of a perforated diaphragm of gutta-percha, or by a 

 glass vessel of that shape (7,note) instead of the cylinder, does not 

 at all diminish the quantity of the current, thereby proving that 

 the currents under consideration do not arise from any action of 

 heat or other force in the body of the liquid. 



22. It makes no difference in the direction of the currents 

 whether the heat be applied to the liquid near the metal or to 

 the metal itself, i. e. whether the heat passes from the liquid to 

 the metal, or vice versa ; a number of careftil experiments clearly 

 established this point. 



23. The effect of constant heat was to produce a constant or 

 nearly constant current, even when the two plates were main- 

 tained at uniform but different temperatures for several hours. 



24. Increasing the depth of the liquid column to about 8 

 inches had no appreciable effect upon the quantity of the cm-rent, 

 there being abundance of conductivity for so small a force ; and 

 increasing the thickness of the plates had no other effect than that 

 of causing the currents to be more slow in manifesting them- 

 selves, in consequence of the heat being longer in reaching the 

 liquid surface. 



25. To ascertain the influence of size and number of the 

 plates, I constructed four apparatuses similar to the one already 

 described (7), but with square copper plates 7x7 inches, and 

 charged them with an acidulated solution of sulphate of copper. 

 I connected them in one instance intensity fashion, i. e. as four 

 successive pairs, and in the other instance quantity fashion, i. e, 

 all the hot plates as one plate, and all the cold ones as another; 

 and tried various comparative experiments with the galvanometer 

 and variable resistances, and found that the intensity of the cur- 

 rent increased with the number of pairs, and the quantity with 

 the amount of surface in each pair. No visible electrolytic 

 effects were produced by several hours' action of this larger ap- 

 paratus upon good conducting solutions, although the current, 

 even of one pair, possessed abundant intensity to traverse long 

 columns of those liquids. 



26. Diminishing the area of liquid contact of the lower plate 

 had the same or nearly the same effect in decreasing the quan- 

 tity of the current as diminishing that of the upper one, thereby 



