REGELATION (Lat. rcip/ortio, a thawing. from to thaw. fro In hao k anew -L go 14trr, to freeze, from gt lot. frost : n neeted with Lith. fp intense edd. ??•th. ka Ng, Nil:. knit, As. co fad. Eng. coil,/ . A term first applied by Faraday to describe flu i 1101 lima occurring who n two 1 loc( s Of be are brought into Mad under pus-or.. Tioe ice melts at the plane of co Motet aml t be wlter us formed freezes whin the I ressun is relieve I. tt us 'militia the 'Nyco Voat ire mu sure, and that its melting- 1 (lint is lowered a- the pressure increases, Was 11E-t 'MI by Prole..or Jan e4 Thomson, and then demonstrated c.f.. ri ti 'molly 1 v his brother, fa rd Ivin. nail this I 1'0) lo•ty to explain tie phem mono in vol v.41 in reoelation. A wheel track in the snow is generally covered with a thin film of ice for the reason that the snow melted by the pressure of the wheels freezes as soon as the pressure is removed. A snowball is made by the pressure of the hands the snow to melt, and then the water is solidified. Consequently if the snow is dry and cold and below the freezing point, the pressure of the hands will not suffice. If a press is used, the snow will be melted and cylindrical or other forms of transparent ice can be formed. The well-known experiment of looping a cord or wire around a block of ice and attaching a weight will also show regelation. Here the pressure on the cord melts the ice and allows the string to cut its way through the block, but at the same time the water thus formed is acain frozen and the block left in its original solid'condition. A union
between two pieces of ice will take place when they are in contact under water, even if the temperature is considerably above that of the air. In such a case. however, the capillary action of the film of water between the two faces renders the internal pressure less than the external and acts to bring the two pieces together with pres sure. The phenomenon of regelation is also quoted to explain the formation and movement of glaciers (q.v.). The glacier in its progressive movement acts much as a viscous solid, the top moving faster than the bottom and the middle faster than the sides. The pressure of the vast quantity of snow above melts the ice or snow at the bottom, and this, escaping and flowing down, freezes and solidifies, a gradual slipping away of the base occurring. As the foot of the glacier descends it reaches warmer regions, so that melt will take place with less pressure and the water will drain off. In this way it is possible to explain lunch of the formation and movement of glaciers, though of course the problem is very complex and other causes exert powerful influ ences. Consult Preston, Theory of Heat (New York, 1894). See HEAT.