520 



Mr. G. Gore on 



No. 12. 14 oz. of water and ^ oz. of pure nitric acid. Platinum 

 plates. Current f 23. Gold plates. Current | 12-5. Palladium 

 plates. Current f 75. Cold water produced a feeble current \. 



No. 13. 14 oz. of water and 1 oz. of pure hydrochloric acid. Pla- 

 tinum plates. Current | 2. Gold plates. Current f 2. Palladium 

 plates. Current f 2. Cold water produced feeble J currents. (Com- 

 pare No. 143.) 



No. 14. 12 oz. of water and 3 oz. of a saturated solution of pure 

 boracic acid. Platinum plates. Current J 1*5. Cold water produced 

 a weak current f . 



No. 15. 12 oz. of water and 4 oz. of crystals of sulphate of copper. 

 Plates of platinum, gold, or palladium, gave J currents, strong with 

 the two first-named metals and feeble with the last ones. (Compare 

 Nos. 42, 43, 44, and 113.) 



No. 16. 12 oz. of water, 4 oz. of crystallized chloride of copper, and 

 ^ oz. of pure concentrated hydrochloric acid. Gold plates. Current 

 | 52J at 160° F.° and 48 at 210° F. Cold water produced a very 

 strong J current. 



No. 17. The same mixture, with platinum plates. Current j 54^ at 

 170° F. and 51J at 210° F. (Compare No. 125.) Cold water strongly 

 reversed the current. 



No. 18. The same mixture, with palladium plates. Current J, 45 at 

 190° F., and 36 at 210° F. Cold water produced a very strong J cur- 

 rent, and the upper plate was found corroded after the experiment. 

 'Remarks. These circumstances show that the downward current was 

 due to the chemical action excited by the higher temperature. This 

 experiment also illustrates the utility of subsequently applying cold 

 water to reveal the true effect of heat in cases where chemical action 

 interferes. (Compare Nos. 32, 60, and 125.) 



No. 19. 7 oz. of water and 6| oz. of a saturated solution of chlorate 

 of copper containing very little free acid. The mixture reddened blue 

 litmus paper. Platinum plates. Current j 28 at 195° F., and 15 at 

 210° F. Cold water produced a J current. (Compare No. 126.) 



No. 20. The same mixture. Gold plates. Current f 5£. Cold 

 water produced a \ current. 



No. 21. The same mixture. Palladium plates. Current j 35. Cold 

 water reduced the deflection to 0. 



No. 22. A nearly saturated solution of nitrate of copper, not con- 

 taining any free acid. Platinum plates. Current f 8J. Cold water 

 reversed the direction of the current. 



No. 23. The same solution. Gold plates. Current f 2 at 180° F. 

 Cold water produced a J current. 



No. 24. The same solution. Palladium plates. Current f 15 j. Cold 

 water produced a | current. 



No. 25, 14 oz. of a nearly saturated solution of cupric nitrate and 



