184 ON THE CONCRETIONARY AND 



Granting the greatest facilities to the preceding 

 supposition, by admitting the solution, in water, of 

 earths, noted for the extremely limited degree in which 

 they possess this property, and granting, still further, 

 that they were able, under these circumstances, to 

 enter into all the multifarious combinations which are 

 to produce quarts, felspar, mica, hornblende, and 

 many other minerals, it remains to invent a new pro- 

 cess in the chemistry of crystallization, by which all 

 these combinations should have been in an instant 

 deposited together in a solid mass. If a successive 

 deposition of the different minerals be conceived, it is 

 impossible to explain the mutual interference which 

 takes place among them, and which characterizes the 

 crystalline granular structure. The imagination that 

 would produce such an effect from such causes,, must 

 not be allowed to flit about vague generalities, but is 

 bound to contemplate steadily every minute circum- 

 stance implied in such a process. 



But nature and art both are ready to prove that 

 this effect takes place without difficulty from fusion. 

 The glasses of our furnaces separate into various 

 mineral compounds on cooling. The same results 

 take place from the cooling of fused basalts, where 

 the previous combinations have all been dissolved by 

 one general fluidity. In the trap rocks, the granitic 

 structure is common; and these, it is granted, are the 

 products of fusion. The lavas of volcanoes, if it 

 could be necessary to insist on facts so well known, 

 are in a state of liquid fusion, in which every integrant 

 earth is left free to enter into such combinations as 

 the infinite complication of affinities may direct. If 

 these are cooled suddenly, they are arrested before 

 they can enter into new compounds, and an uniform 

 rock, or sometimes a glass, is the result. If, on the 



