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When the wire was very fine, about theone-eightieth of an inch in diameter, its heatincreased in very combustible mixtures, soas to explode them. The same wire in lesscombustible mixtures only continued brightred, or dull red, according to the nature ofthe mixture.

In mixtures not explosive by flame withincertain limits, these curious phenomena tookplace whether the air or the inflammablegas was in excess.

The same circumstance occurred withcertain inflammable vapours. I have triedthose of ether, alcohol, oil of turpentine, andnaphtha. There cannot be a better modeof illustrating the fact, than by an experi-ment on the vapour of ether or of alcohol,which any person may make in a minute.Let a drop of ether be thrown into a coldglass, or a drop of alcohol into a warm one.Let a few coils of wire of platinum of theone-sixtieth or one-seventieth of an inch beheated at a hot poker or a candle, and let itbe brought into the glass; it will in somepart of the glass become glowing, almostwhite hot, and will continue so as long as a