Elements of Physics

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: mcna of heat are produced by an exceedingly subtile fluid or ether pervading the whole universe, and softening or melting or gasifying bodies, according to the quantity present in each, its own parts being strongly repulsive of each other, and seeking therefore widest and most equable diffusion. The change...
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Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: mcna of heat are produced by an exceedingly subtile fluid or ether pervading the whole universe, and softening or melting or gasifying bodies, according to the quantity present in each, its own parts being strongly repulsive of each other, and seeking therefore widest and most equable diffusion. The change of its quantity in bodies is most conveniently estimated by the concomitant change of their bulk, any substance so circumstanced as to allow this to be accurately measured, constituting a thermometer (Readthe Analysis, page 6.) If we heat a wire it is lengthened; if we heat water in a full vessel, a part runs over; if we heat air in a bladder, the bladder is distended: in a word, if we heat any substance, its volume increases in some proportion to the increase of temperature, ? and we may measure the increase of volume. The reasons why, in such investigations, a contrivance in which the expansion of mercury may be observed, 'viz. the mercurial thermometer, is commonly preferred to others, can only be fully understood by the mind which has considered the whole subject of heat; and we touch upon the matter here, only for the purpose of stating that a mercurial thermometer is a small bulb or bottle of glass filled with mercury, and having a long very narrow stalk or neck, in which the mercury rises when expanded by heat, or falls when heat is withdrawn; the stalk between the points at which the mercury stands in freezing and in boiling water, being divided into an ar chapter{{Section 4bitrary number of degrees, which division appearing on a scale applied to the stalk, is continued similarly above and below these points. Heat diffuses itself among neighbouring bodies until all have acquired the same temperature; that is to say, until all will similarly affect a the...