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very large quantity of steam was necessaryto prevent sulphur from burning. Oxygeneand hydrogene exploded by the electricspark when mixed with five times their vo-lume of steam ; and even a mixture of airand carburetted hydrogene gas, the leastexplosive of all mixtures, required a thirdof steam to prevent its explosion, whereasone-fifth of azote produced the effect.—These trials were made over mercury, heatwas applied to water above the mercury, and37.5 for 100 parts was regarded as the cor-rection for the expansion of the gases.

It is probable that with certain heatedmixtures of gases, where the non-support-ing or non-inflammable elastic fluids are ingreat quantities, combination with oxygenewill take place, as in the instance men-tioned, page 83, of hydrogene and chlo-rine, without any light, for the tempera-ture produced will not be sufficient to ren-der elastic media luminous; and there areno combustions, except those of the com-pounds of phosphorus and the metals, inwhich solid matters are the result of combi-nations with oxygene. I have shewn, page53, that the light of common flames dependsalmost entirely upon the deposition, ignition