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the stony particles being without support, separate 

 from each other, and fall from the mass. This, it is 

 universally admitted, is the manner in which the disin- 

 tegration of rocks is produced, by the operations of 

 cold, or by frost. 



Having ascertained the manner in which this agent 

 acts in the decomposition of rocks, or other mineral 

 substances, we are enabled by certain criteria, precise- 

 ly to ascertain, the substances liable to its effects, and 

 the full extent of its power and influence upon all mi- 

 neral substances. 



For example, let a mass of sand stone, dolomite, or 

 other substance, in the form of a cube of any dimension, 

 be emersed in water, or subjected to rain, until the wa- 

 ter has penetrated to the depth of one inch in every face 

 of the cube ; then let the mass be exposed to a degree 

 of cold, that shall freeze it to the same depth that the 

 water has penetrated ; afterwards let the mass be sub- 

 jected to a degree of heat, that shall operate uniformly 

 upon each face of the cube, until the frost is removed, 

 and the substance of the mass falls away to the extreme 

 depth to which it was frozen. 



What sort of a figure will the mass represent under 

 such circumstances ? Not, certainly, that of a regular 

 cube; every point and angle thus exposed, will be 

 rounded down, and if the operation be repeated, for in- 

 stance, through a succession of seasons, the mass will 

 become a sphere, and thus progress until reduced to a 

 point, or completely dissolved. 



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