130 Mr. Grove on the Combination of Gases by Platimim. 



other, passed, hermetically sealed, through the bottom of a 

 bell glass ; the projecting ends were made to communicate 

 with a delicate galvanometer; the glass was filled with water 

 acidulated with sulphuric acid, and both the platina strips 

 made the positive electrodes of a voltaic battery until per- 

 fectly clean, &c. ; contact with the battery having been 

 broken, over each piece of platinum was inverted a tube of 

 gas, four-tenths of an inch in diameter, one of oxygen, the 

 other of hydrogen, acidulated water reaching a certain mark 

 on the glass, so that about half of the platina was exposed to 

 the gas, and half to the water. The instant the tubes were 

 lowered so as to expose part of the surfaces of platinum to 

 the gases, the galvanometer needle was deflected so strongly as 

 to turn more than half round : it remained stationary at 15°, 

 the platinum in the hydrogen being similar to the zinc element 

 of the pile. When the tubes were raised so as to cover the 

 plates with water, the needle returned slowly to zero ; but the 

 instant that the tubes were lowered again, it was again deflect- 

 ed ; if the tubes were changed with regard to the platina, the 

 deflection was to the contrary side. 



The action lowered considerably after the first few minutes, 

 but was in some degree restored every time the tubes were 

 raised so as to wash the surface of the platina, and again low- 

 ered. After 24; hours, the water had risen half an inch in the 

 tube containing hydrogen, and three eighths of an inch in that 

 containing oxygen. In two other tubes, without platina, but 

 with the same gases and immersed in acidulated water for the 

 same time, the water had scarcely perceptibly risen, the effect 

 therefore could not have been due to solution ; the same sheets 

 of platinum were exposed to atmospheres of common air and 

 of similar gases, i. e. both to oxygen or both to hydrogen, &c., 

 but without affecting the galvanometer. The platinum in the 

 hydrogen was made the positive, and that in the oxygen the 

 negative electrode of a single voltaic pair ; the water now rose 

 at the rate of three-eighths of an inch per hour in the hydrogen 

 tube and proportionally in the oxygen ; when the platina was 

 not assisted by a pair of metals the oxygen was absorbed in 

 more than its' relative proportion. I hope, by repeating this 

 experiment in series, to effect decomposition of water by 

 means of its composition. 



