Page:Report from the Select Committee on Steam Carriages.pdf/59



Mr. G. Gurney. 5 August, 1831. rail-road, I believe there is a clause in their Act to prevent any nuisance being made by smoke, and coke is therefore used; but in the ordinary rail-roads in Wales and other places, coal is used.

In what part of your Engine is your safety valve situated?—It is situated at the option of the Engineer; frequently in the steam pipe leading from the boiler to the Carriage, most generally; so that the steam as it passes through that pipe may lift the safety valve, or it may go to the Engine, as the state of pressure shall determine.

Do you make use of one or two safety valves?—Only one, I occasionally use two, but we now use only one.

If your Carriages were brought into general use, would you suggest that two safety valves should be required, one out of the reach of the Engineer to prevent accidents occurring from racing, or other causes which could induce the guide to increase the pressure of Steam?—I should recommend one being locked, and an Inspector being appointed to examine it every journey. Perhaps I may be allowed to make an observation or two with respect to the bursting of boilers, which subject, I believe, is now under consideration. From experiments which I have made in connection with this subject, I am led to believe that the bursting of boilers is not always occasioned by pressure of steam. I have discovered that at a certain degree of temperature and under certain circumstances, when water is decomposed, that the hydrogen is often formed into a new state of combination with oxygen and nitrogen gas, which compound is exceedingly explosive; so much so, that I believe scarcely any provision that we can make in the shape of a Safety valve, would protect the vessel. This was a subject which I was led to some time ago, from some observations which I had made on the combinations of oxygen and hydrogen only. I had some conversation with Gay Lussac on this subject, and he was of the same opinion with myself, particularly that there were different chemical compounds of hydrogen and oxygen gasses which at present were not