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and when the gage indicated a pressurebetween 4 and 5 times less than that of theatmosphere was at its maximum of size, itthen gradually diminished below, but burnedabove till the pressure was between 7 and 8times less, when it became extinguished.

To ascertain whether the effect dependedupon the deficiency of oxygene, I used alarger jet with the same apparatus, whenthe flame to my surprise burned longer, andwhen the atmosphere was rarefied ten times,and this in repeated trials. When the largerjet was used, the point of the glass tubebecame white hot, and continued red hot tillthe flame was extinguished. It immediatelyoccurred to me, that the heat communicatedto the gas by this tube, was the cause thatthe combustion continued longer, in the lasttrials when the larger flame was used; andthe following experiments confirmed theconclusion. A piece of wire of platinumwas coiled round the top of the tube, so asto reach into and above the flame. The jetof gas of one-sixth of an inch in height waslighted and the exhaustion made; the wireof platinum soon became white hot in thecentre of the flame, and a small point of