[Frost and fire : natural engines, tool-marks and chips : with sketches taken at home and abroad by a traveller] . a solid iceroof, thermometers mark 32° 33°3-t°35°and the blackest layer in the series is the lowest and thewarmest. When freezing water freezes, ciystals expel colour fromice, and water-currents distribute paint amongst the remain-ing fluid. Circulation goes on under ice, for some of the darkwater which was next below the ice when it began to formis found at the bottom when all the instruments read closeupon 32°, and the solid crust has formed. Water, then, is a gas, a fluid, and
[Frost and fire : natural engines, tool-marks and chips : with sketches taken at home and abroad by a traveller] . a solid iceroof, thermometers mark 32° 33°3-t°35°and the blackest layer in the series is the lowest and thewarmest. When freezing water freezes, ciystals expel colour fromice, and water-currents distribute paint amongst the remain-ing fluid. Circulation goes on under ice, for some of the darkwater which was next below the ice when it began to formis found at the bottom when all the instruments read closeupon 32°, and the solid crust has formed. Water, then, is a gas, a fluid, and a solid at different tem-peratures ; and the formation of oue crust on one fluid illus-trates the formation of other crusts. The ice crust forms next the coldest place, and the fluidremains shut up inside. In a tank the process can be watched, and the disposi- 78 WATER. tion of tlie crust is seen, because ice is transparent, and ver-tical glass walls bound ice planes through which rays passundistorted. A plate of ice seven inches broad is moretransparent edgewise, than an equal thickness of Fig. 16. Frozen. *—^ It refracts rather less than water. On the surface, the iceis disposed in layers, whose planes coincide with those whichcolour shewed in freezing water. The layers are addedbelow; they are horizontal and regular where the ice issmooth above ; where the ice is rough outside, the planes ofstratification within are bent and crumpled. The surfacenext the wall is a plane, where the layers are flat and undis-turbed ; it waves where the strata are bent and wrinlded. The thickness of the-upper crust varies ; at corners, theangular solid is rounded off, so as to form a dome. From these solid corners long blade-like crystals radiateat all angles from 1° to 90°. They are like spokes of wheels,whose common centres are the corners of the tank ; or as WATKK. 79 faus behind the glass, opening from the angles where threeplanes meet. Each of these blades is like t
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Keywords: ., bookpublisheredinburghsn, booksubjectgeo, booksubjectmeteorology
