8 
MR. GROVE ON THE DECOMPOSITION OF WATER BY HEAT. 
current through the asbestos by washing away fine particles, and the phenomena of 
ordinary ebullition took place, unless the intensity of the battery was very much ex- 
alted, when a very slight decomposition was perceptible, which I attributed to electro- 
lysis. 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: 
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 in- 
stant a tremulous motion was perceptible, and separate bubbles of permanent gas of 
the size of pin-heads ascended, 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 intermitting 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 supposition, yet as this was my first successful experiment on this sub- 
ject, and is per se an interesting and striking method of showing the phenomenon of 
decomposition by heat, I will mention a few points to prove that the phenomenon 
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 divided 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 performed with distilled 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. 
3rdly. 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 
* January 8. — I have since found that the exterior tube of oil or water may be dispensed with in this ex- 
periment, as the water which trickles down prevents the fusion of the glass. 
