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the light of the stream of coal gas mightbe owing to the decomposition of a part ofthe gas towards the interior of the flamewhere the air was in smallest quantity, andthe deposition of solid charcoal, which, firstby its ignition, and afterwards by its com-bustion, increased in a high degree the in-tensity of the light; and a few experimentssoon convinced me that this was the truesolution of the problem.

I held a piece of wire gauze, of about900 apertures to the square inch, over astream of coal gas issuing from a small pipe,and inflamed the gas above the wire gauze,which was almost in contact with the orificeof the pipe ; when it burned with its usualbright light. On raising the wire gauze soas to cause the gas to be mixed with moreair before it inflamed, the light becamefeebler; and at a certain distance the flameassumed the precise character of that of anexplosive mixture burning within the lamp;but though the light was so feeble in thislast case, the heat was greater than whenthe light was much more vivid, and a pieceof wire of platinum held in this feeble blueflame became instantly white hot.

On reversing the experiment by in-