New conversations on chemistry, adapted to the present state of that science; wherein its elements are clearly and familiarly explained. With one ... of experiments, and a #. On the foundation of
Thomas P. Jones
Paperback
(RareBooksClub.com, March 4, 2012)
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1832 Excerpt: ...coal, and mixing with the air of the atmosphere, forms an explosive compound, which takes fire from the flame of a lamp, or candle, killing the miners, and destroying their works(62). Davy, however, ascertained that if the flame of a lamp were surrounded completely by wire gauze, the meshes of which are fine, but still sufficiently open to afford a good light, it might be safely carried into the most explosive mixture(63). Caroline. In looking at the thing, this appears so unlikely that I cannot imagine by what train of reasoning Davy arrived at such a conclusion. Mrs B. He arrived at it by the most acute reasoning, founded upon laborious experimental investigation. Wollaston had observed that explosive mixtures would not burn in narrow tubes, and Davy, pursuing this idea, found that if the bore was very small, the tube might also be made extremely short, and still explosive gases could not be lighted through it. Now the wire gauze may be considered as formed of a great number of such tubes, the length of which is equal to the diameter of the wire(64). Emily. Yet the gas must pass freely through these openings, and get into the lamp. Mrs B. Certainly, and sometimes it explodes there without doing any harm: at others, thewbole interior of the lamp will befilled with flame, the wire will become red-hot, and yet the gas at the outside will not be ignited. Caroline. But what can protect the gas in the mine from being ignited by the red-hot wire of the lamp? That seems incomprehensible. Mrs B. It requires a very intense heat to set fire to the gas; and it has been ascertained that flame, although the light which it emits may be feeble, is much hotter than metal even when at a glowing red heat. A wire thus heated may be safely put into an explosive mixture, whils...