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carburetted hydrogene and air, and a bladdertwo-thirds or one-half full of the same mix-ture, both insulated from the atmosphere. Bymeans of wires passing near the stop-eockof the glass vessel, I fired the explosivemixture in it by the discharge of a Leydenjar. The bladder always expanded at themoment the explosion was made; a contrac-tion as rapidly took place ; and a lambentflame played round the mouths of the safetyapertures, open in the glass vessel; but themixture in the bladder did not explode:and by pressing some of it into the glassvessel, so as to make it replace the foul air,and subjecting it to the electric spark, re-peated explosions were produced, provingthe perfect security of the safety apertures;even when acted on by a much more pow-erful explosion than could possibly occurfrom the introduction of air from the mines.

These experiments held good whateverwere the proportions of the explosive mix-ture and whatever was the size of the glassvessel, (no one was ever used containingmore than a quart) provided as many as 12metallic tubes were used of one-seventh ofan inch in diameter, and two and a half