Atmosphere : a philosophical work / by George Woodhead.

  • Woodhead, George.
Date:
1852
Catalogue details

Licence: Public Domain Mark

Credit: Atmosphere : a philosophical work / by George Woodhead. Source: Wellcome Collection.

    30/164 page 18
    To the effects produced by tlie burning- glass, whether it be the burning of a piece of wood, or the melting of a piece of iron, both light and air contribute. It is cer- tain that both those agents are present in the operation; and we do not know that any other agent is present; and, in the absence of either of them, the burning- glass will not burn. If a light from a lens, which sets substances on fire, be thrown into the same substances in an exhausted receiver, it wiU produce no per- ceptible effect on some of them. It will not ignite gunpowder. If a bm^ning light be thrown upon gunpowder in a glass receiver well exhausted, it produces no perceptible effect so long as the vacuum is tolerably good. As the air retm-ns into the receiver, and is accumulated in the grains of powder by the light which enters them, they begui to smoke and jump about; but the light will not inflame them until the receiver is replenished with air. Gunpowder cannot by any means be made to explode in vacuo. I have seen the
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