28 Mr. Grove on the Decomposition of Water hy Heat. 



appeared by the last two experiments, quantity had any influ- 

 ence, that it might be possible so to divide the mixed gases 

 by a quantity of a neutral ingredient as to obtain them by 

 subsequent separation (or as it were filtration) from the neu- 

 tral substance. Both these ideas were realized. 



To effect the first object, after, as usual in such circum- 

 stances, much groping in the dark, I cemented a loop of pla- 

 tinum wire in the end of a tube retort similar to fig. 3, and 

 covered it with asbestos, ramming this down so as to form a 

 plug at the closed extremity of the tube, the platinum wire 

 being in the centre. My object was, by igniting the platinum 

 wire, to drain the water out of the asbestos, and the ignited 

 wire being then in an atmosphere of steam, I hoped the water 

 would by capillary attraction keep constantly oozing down to 

 the platinum wire as the steam or decomposed water ascended. 

 The experiment did not succeed ; the water established a 

 current through the asbestos by washing away fine particles, 

 and the phaenomena of ordinary ebullition took place, unless 

 the intensity of the battery was very much exalted, when a 

 very slight decomposition was perceptible, which I attributed 

 to electrolysis. This experiment, however, suggested another 

 which did succeed. In one or two cases the asbestos plug 

 became compressed above the platinum and so choked up the 

 tube that the wire suddenly fused. It now occurred to me 

 that by narrowing the glass tube above the platinum wire I 

 had the result at my command, as the narrow neck might be 

 made of any diameter and length, so as just to allow the water 

 to drip or run down as the steam forced its way up; a tube 

 was so formed, and is shown with its accompaniments at fig. 5. 



Fig. 5. 



The result of this experiment was very striking: when two 

 cells of the nitric-acid battery were applied the air was first 

 expanded and expelled, the water then soon boiled, and at a 

 certain period the wire became ignited in the steam. At this 

 instant a tremulous motion was perceptible, and separate 

 bubbles of permanent gas of the size of pin-heads ascended, 



