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lamps were placed under the tube where itentered the charcoal fire, and the mixturewas very slowly pressed through : an explo-sion took place before the tube was red hot.

This experiment shows that expansionby heat, instead of diminishing the combus-tibility of gases, on the contrary, enablesthem to explode apparently at a lower tem-perature, which seems perfectly reasonable,as a part of the heat communicated by anyignited body must be lost in gradually rais-ing the temperature. I made several otherexperiments which establish the same con-clusions. A mixture of common air andhydrogene was introduced into a smallcopper tube, having a stopper not quitetight; the copper tube was placed in acharcoal fire; before it became visibly redan explosion took place, and the stopper wasdriven out.

I made various experiments on explo-sions by passing mixtures of hydrogene andoxygene through heated tubes; in the be-ginning of one of these trials, in which theheat was much below redness, steam ap-peared to be formed without any combus.tion. This led me to expose mixtures of