-158 



ILLUSTRATIONS OF THE 



decompoiition, might afford a carbonic bafis; 

 fufficient for the coal beds of all the furround- 

 ing plains. 



145. We m ay al fo obj e 61 to MrKirwan,thatthe 



I r 



iiliceous part of the mountains has not been che- 

 mically diffolved ; it has been only abraded and 



worn away 



Mechanical action has reduced the 



i 



* 





\ 



y\ 



w 



quartz to gravel and fatid, but has not produced 

 «on it any chemical change. The carbon, there- 

 fore, could not be let loofe. Experiment, in- 

 deed, might be einplo)ed, to determine whether 



r 



the filiceous matter of the fecondary, and of 

 the primary ftrata contains this fubllance in the 



fame proportion. 



Again, a more fatal fymptom can hardly be 

 imagined in any theory, than that, when the cir- 

 cumftances of the phenomena to be explained are 



r 



a little changed, the theory is under the neceffi- 

 ty of changuig a great deal. Now, this is what 

 happens to Mr Kirwan's theory, in the attempt 

 made to explain by it the ftratum of coal de- 

 fcribed in the Annales de Chimie^, as cutting a 

 mountain of argillaceous ftrata in two, at about 



s ftratum, Mr 



three fourths of its h 



Th 



y. 



J 



^ 



t. 



Kirwan ftiys, muft have been formed by tranju- 



dation from the fuperior part of the mountain f 



Befides that this is a gratuitous fuppolition of £ 



thing; 





*■* 





Tom.xL p. 27 



t Geol. E%s, p^ssS 



