20 



ILLUSTRATIONS OF THE 



where water runs in a ft ream, or drops from 

 the roof of a cavern. The two lafl condi- 

 tions are peculiarly inapplicable to the bottom 

 of the fea, where the Hate of the furrounding 

 fluid would neither permit the water that was 

 deprived of its folution from being drawn off, 

 nor that which contained the folution from fue- 



ceeding it. 



It is further to be obferved, that the confoli- 

 dation of (tala6titical concretions, that is, the fill- 

 ing up of their pores, is always imperfedl, and is 

 brought about by the repeated adlion of the fluid 

 running through the porous mafs, and continu- 

 ing to depofite there fome of the matter it holds 

 in folution. This, which is properly infiltra- 

 tion, is incompatible with the nature of a fluid, 

 either nearly, or altogether quiefcent. 



15, in order to judge whether objeflions of 

 equal weight can be oppofed to the hypothefis 

 of igneous confolidation, we muft attend to a 

 very important remark, firil made by l>r Hut- 

 ton, and applied with wonderful fuccefs to e:s- 



plain the mofl: myfl;erious phenomena of the 



mineral kingdom. 



It is certain, that the efFeds of fire on bo- 



^m 



dies vary with the circumfl:ances under which 

 it is applied to them, and therefore a confider- 



able allov/ance muft be made^ if we would com- 

 pare 



L 



