Inhaltsangabe
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.1868 Excerpt: ... CHATTEB VIIT. THE COAL FIRE. If, musing in front of a cheerful fire, our thoughts are turned to a consideration of its cause and effects, many questions worthy of a well considered answer will be suggested. Some of these we intend to consider. What coal is, and why it burns, we have already explained. We have also traced the effect of heat produced by combustion when conducted from one body to another, in changing temperature and introducing new conditions of matter. Our business is now to observe, not another mode of effecting the transport of heat, but, if we may so speak, to see how heat transfers itself. The origin, processes, and effects of combustion being known, and the laws of expansion by increased temperature, we may confine our lesson on the coal-fire to a study of the phenomena of radiation. The heat received from a fire kindled in such open grates as are used in the dwelling-houses of Great Britain, is not principally duo to any effect produced directly upon the atmosphere of the room. The great mobility among the particles of gases and1 vapours, giving to the elastic fluids their physical distinctions, prevents, as we have said, that communication of heat by conduction which is effected through solid bodies. Air is practically a non-conductor of heat, and if this be its condition in relation to that force, the temperature of an atmosphere cannot be raised in the mass by contact with a source of heat. So far as the air is concerned, the increase of temperature must be caused by the communication of heat to the particles separately. This is made possible by the free motion of the constituent parts, and the ease with which they move among each other. The process is simple and evident. The temperature of each part, as it comes into contact with a ...
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