Mr. Grove on the Decompositioji of Water hy Heat. 29 



and formed a volume in the bend of the tube. It was not a 

 continuous discharge of gas as in electrolysis, but appeared to 

 be a series of rapid jerks ; the water, returning through the 

 narrow neck, formed a natural valve which cut off by an in- 

 termitting action portions of the atmosphere surrounding the 

 wire; the experiment presented a novel and indescribably 

 curious effect. The gas was oxyhydrogen. It will occur at 

 the first to many of those who hear this paper read, that this 

 effect might be derived from electrolysis. No one seeing it 

 would think so for a moment; and although I shall by my 

 subsequent experiments, I trust, abundantly negative this sup- 

 position, yet as this was my first successful experiment on this 

 subject, and is 'per se an interesting and striking method of 

 showing the phaenomenon of decomposition by heat, I will 

 mention a few points to prove that the phaenomenon could 

 not be occasioned by electrolysis. 



To account for it by electrolysis, it must be supposed that 

 the wire offered such a resistance to the current that this di- 

 vided itself, and the excess of voltaic power passed by the 

 small portion of water which trickled down, instead of by the 

 wire. 



In the first place, the experiment was perfornved with di- 

 stilled water, and only two cells of the battery employed, which 

 will not perceptibly decompose distilled water. 



2ndly. No decomposition took place until the instant of 

 ignition of the wire, though there was a greater surface of 

 boiling water exposed to the wire before than after the period 

 of ignition. 



Srdly. A similar experiment was made, but with the wire 

 divided in the centre so as to form two electrodes, and the 

 water boiled by a spirit-lamp ; here the current had no wire 

 to conduct any part of it away, but the whole was obliged to 

 pass across the liquid, and yet no decomposition took place, 

 or if there were any it was microscopic. 



4thly. When, instead of oil, distilled water was used in the 

 outer vessel*, even the copper wires, oneof which would form 

 an oxidable anode, gave no decomposition across the boiling 

 water outside, while the ignited wire inside was freely yielding 

 mixed gases. 



5thly. To prevent the water from being the shortest line 

 for the current, I repeated the experiment with a perfectly 

 straight wire (fig. 6). The result was precisely the same, 

 but the experiment is more difficult ; as a certain length of 



* January 8.— I have since found that the exterior tube of oil or water 

 may be dispensed with in this experiment, as the water which trickles 

 down prevents the fusion of the glass. 



