THE PEDALTO INSTITUTION FOR INCORPORATED ART

 
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BUREAU OF BUREAU DILATION

DIRECTOR   Everette Koonce

ABOUT

One of the most remarkable properties of heat is the repulsion which exhits among its partieles, a property which enables it, on entering into a body, to remove the integrant molecules of the substanee to a greater distance from each other. The body, therefore, becomes less compact than beiore. oecupics a greater apace, or, in other words, expands. This effect of heat is opposed to cohesion—that foree which tends to make the partieles of matter approximate, and which must be overeome before any expansion can ensue. It may be expected, therefore, that a small addition of heat will occasion a small expansion, and a greater addition of heat a greater expansion ; because in the latter case, the cohesion will be more overeome than in the former. It may be anticipated, also, that whenever heat passes out of a body, the cohesion being then left to act frcely, a contraction will necessarily follow ; so that expansion is only a transicnt effect, oecasioned solely by the aecumulation of heat. It follows, moreover, from this vicw, that heat should produce the greatest expansion in those bodics which are least influeneed by cohesion, an inferenee fully justified by observation. Thus the foree of cohesion is greatest in solids, less in liquids, and least of all in aeriform substances ; while the expansion of solids is trifling, that of liquids much more considerable, and that of elastic fluids far greater.