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me to the discovery of the principles bywhich explosion and flame may be arrestedand regulated; and by means of which, theminer is not only able to subdue and con-troul, but likewise to render useful his mostdangerous enemy.

I first began with a minute chemical ex-amination of the substance with which Ihad to contend.—The analysis of variousspecimens of fire damp shewed me that thepure inflammable part of it was light car-buretted hydrogen, as Dr. Henry had beforestated, hydrogen or pure inflammable aircombined with charcoal or carbon.

I made numerous experiments on the cir-cumstances under which it explodes, and thedegree of its inflammability.—I found thatit required to be mixed with very largequantities of atmospheric air to produce ex-plosion, even when mixed with three ornearly four times its bulk of air, it burntquietly in the atmosphere, and extinguisheda taper. When mixed with between five andsix times its volume of air it exploded feebly:it exploded with most energy when mixedwith seven or eight times its volume of air,and mixtures of fire damp and air retained