61

nished with the wire when the pressure wasbelow one-fourth.

The flame of carbonic oxide which,though it produces little heat in combustion,is as inflammable as hydrogene, burnedwhen the wire was used, the pressure beingone-sixth.

The flame of sulphuretted hydrogene,the heat of which is in some measure carriedoff by the sulphur produced by its decom-position during its combustion in rare air,when burned in the same apparatus as theolefiant and other gases, was extinguishedwhen the pressure was one-seventh.

Sulphur, which requires a lower tem-perature for its combustion than any com-mon inflammable substance, except phos-phorus, burned with a very feeble blue flamein air rarefied fifteen times, and at thispressure the flame heated a wire of platinumto dull redness, nor was it extinguished tillthe pressure was reduced to one-twentieth.*

* The temperature of the atmosphere diminishes in acertain ratio with its height, which must be attended toin the conclusions respecting combustion in the upperregions of the atmosphere, and the elevation must be