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mercury by heat, would not inflame by theelectric spark. It is evident, that in thisexperiment a large quantity of steam or ofmercurial vapour must have been present,which like other inexplosive elastic fluids,prevents combustion when mixed’ in certainquantities with explosive mixtures; butthough he seems aware that his gases werehot dry, yet he draws his general conclusion,that expansion by heat destroys the explosivepowers of gases, principally from this incon-clusive experiment.

I introduced into a small graduated tubeover well boiled mercury, a mixture of twoparts of hydrogene and one of oxygene, andheated the tube by a large spirit lamp tillthe volume of the gas was increased from 1to 2.5. I then, by means of a blow pipeand another spirit lamp, made the upperpart of the tube red hot, when an explosioninstantly took place.

I introduced into a bladder a mixtureof oxygene and hydrogene, and connectedthis bladder with a thick glass tube of aboutone-sixth of an inch in diameter and threefeet long, curved so that it could be gradu-ally heated in a charcoal furnace; two spirit