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opened in the atmosphere; and that me-tallic tubes prevented explosion better thanglass tubes.

In reasoning upon these various phe-nomena it occurred to me, as a considerableheat was required for the inflammation ofthe fire damp, and as it produced in burn-ing comparatively a small degree of heat,that the effect of carbonic acid and azote,and of the surfaces of small tubes in pre-venting its explosion, depended upon theircooling powers; upon their lowering thetemperature of the exploding mixture somuch that it was no longer sufficient for itscontinuous inflammation.

This idea, which was confirmed by va-rious obvious considerations, led to an im-mediate result—the possibility of construct-ing a lamp, in which the cooling powers ofthe azote or carbonic acid, formed by com-bustion or the cooling powers of the aper-tures, through which the air entered ormade its exit, should prevent the communi-cation of explosion.

I first tried the effects of lamps in whichthere was a very limited circulation of air;and I found that when a taper in a close