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hi more rarefied air than those that producelittle heat : and every experiment I havemade confirms these conclusions. Thusolefiant gas which approaches nearly tohydrogene in the heat produced by its com-bustion, and which does not require a muchhigher temperature for its inflammation,when its flame was made by a jet of gasfrom a bladder connected with a small tubefurnished with a wire of platinum, under thesame circumstances as hydrogene, ceased toburn when the pressure was diminishedbetween 10 and 11 times: and the flamesof alcohol and of the wax taper whichrequire a greater consumption of heat forthe volatilization and decomposition of theircombustible matter, were extinguished whenthe pressure was five or six times less withoutthe wire of platinum, and 7 or 8 times lesswhen the wire ivas kept in the flame.Light carburetted hydrogene, which pro-duces, as will be seen hereafter, less heat incombustion than any of the common com-bustible gases, except carbonic oxide, andwhich requires a higher temperature for itsinflammation than any other, had its flameextinguished, even though the tube was fur-