Scientific amusements . cold isrelative. ,When we enter a cellar in the summer when,the exterior air is warm, we find the cellar cold; if weenter during the wintry weather, we find the temperaturerather warm. Nevertheless it remains about the sameheat all the while. Suppose that we hold the right hand in a vessel con-taining hot water, and the left hand in a vessel containingcold water ; if we then withdraw our hands at the samemoment and plunge them together into a third vessel fullof tepid water, we shall then experience two differentsensations, heat and cold, proceeding from water of acerta
Scientific amusements . cold isrelative. ,When we enter a cellar in the summer when,the exterior air is warm, we find the cellar cold; if weenter during the wintry weather, we find the temperaturerather warm. Nevertheless it remains about the sameheat all the while. Suppose that we hold the right hand in a vessel con-taining hot water, and the left hand in a vessel containingcold water ; if we then withdraw our hands at the samemoment and plunge them together into a third vessel fullof tepid water, we shall then experience two differentsensations, heat and cold, proceeding from water of acertain temperature. The study of heat and caloric can be immediatelyundertaken without any apparatus, as we have seen whendealing with other branches of physics. THE CONDUCtlBILlTY OF METALS. 67 The Conductibility of Metals. a burning coal on a muslin hand kerchief. Take a globe of copper, about as large as the globularornaments which one sees at the bottom of a staircase,and wrap it in muslin or, in a cambric Fig. 56.—A Burning Coal placed on a Handkerchief wrapped round a Copper Handkerchief is not scorched. Place on this metallic bowl, thus enveloped, a redhotcoal, and it will continue to glqw, without in any waydamaging the muslin wrapper. The reason is this : themetal being an excellent conductor absorbs all the heat 68 HEAT. developed by the combustion of the coal, and as thehandkerchief has not absorbed any of the heat, it remainsat a, lower temperatmre to that at which it would beinjured (Fig. 56). ^
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Keywords: ., bookcentury1800, bookdecade189, booksubjectscientificrecreations
