On November 9th Davy read his first paper on the subject before the Royal Society; it was entitled “On the fire-damp of coal mines, and on the methods of lighting the mines so as to prevent its explosion.” After describing the manner in which his attention had been specially called to the subject, he states that he first made experiments with a variety of phosphori (Kunckel’s, Canton’s, and Baldwin’s), and also with the electrical light in close vessels, in the hope that they might be found to afford the requisite amount of illumination; but the results were not encouraging.
After an account of the chemical characters of the fire-damp sent to him by Mr. Hodgson, he describes the results of experiments on its combustibility and explosive nature, and on the degree of heat required to explode it when mixed with air. In respect of its combustibility fire-damp was found to differ most materially from the other common inflammable gases in that it required a far higher temperature to effect its inflammation or explosion. Moreover, it was found that the flame formed by the union of air and fire-damp would not pass through tubes of a certain minimum diameter;
“and in comparing the power of tubes of metal and those of glass, it appeared that the flame passed more readily through glass tubes of the same diameter; and that explosions were stopped by metallic tubes of one-fifth of an inch when they were an inch and a half long; and this phenomenon probably depends upon the heat lost during the explosion in contact with so great a cooling surface, which brings the temperature of the first portions exploded below that required for the firing of the other portions. Metal is a better conductor of heat than glass; and it has been already shown that fire-damp requires a very strong heat for its inflammation.”
The observation that mixtures of air and coal-gas would not explode in very narrow tubes had been previously made, unknown to Davy, by Wollaston and Tennant. Davy likewise found that explosions would not pass through very fine wire sieves or wire gauze. He also noted that an admixture of carbonic acid and nitrogen, even in small proportions, with explosive mixtures of fire-damp greatly diminished the velocity of the inflammation.