Mr. Kirwan^i Refutation of the Huttonian Theory. 7 



quite original, in the farcaftic fenfc in which Mr. Playfair ap- 

 plies this wore! ; but it is evident irritation Was his fole purpofe. 



Air. Playfair adds, "' We may alio objed to Mr. Kirwan, 

 that the riliccous part of the tnountain has not been chemi- 

 callv din()lved ; it has only been abraded and worn away. 

 Mechanical action has reduced the quartz to gravel and fand, 

 but has not produced on it any chemical change ; the car- 

 bon, therefore, could not be let loofe." Mr. Kirwan has not 

 afTumed, that carbon was fet loofe from quartz, though it 

 iTiiiiht have been from filiccous fchifti and other compound 

 lloiies and rocks: difintegration is often eficcled by decom- 

 pofuion; thus felfpar is converted into argil and filiceous 

 particles in many inftances ; but this more frequently hap- 

 pens to ftones that contain iron. 



Page 158. Mr. Playfair, objefting to' ftrata formed by 

 trmijudati07i, alks what occupied the fpace of the coal becl 

 before the tranfudation from the upper part of the mountaiiis. 

 The queftion is unfair, and very fimilar to the numerous dif- 

 ficulties obje6led to Dr. Black's difcovery of fixed air, before 

 its truth was generally acknowledged. A fa6l is often dif- 

 covered, though the mode of its produftion be unknown; yet 

 in this cafe "the queftion is eafily anfwered : the carbonic 

 part of the coal in the mountain of St. George's here alluded 

 to was formed before the upper part of the mountain was 

 formed; it is only the bituminous ingredient that fubfequently 

 tranfuded from the fupervenient luperior itrata ; and I lup- 

 pofe it will be admitted that petrol might penetrate and coa- 

 lefce with the carbonaceous part, without floating the upper 

 part of the mountain, as Mr. Playfair hidicroufly fuppofes. 

 This account is fo much the more probable, as this moim- 

 tain is formed of a mixed calcareous flone abounding in argil ; 

 and this fpecics of calcareous (tone is of fccondary formation, 

 as Mr. HalTenfraz, the author of this memoir, truly remarks, 

 p. 266. 



Mr. Pla^'fair concludes by remarking, " that fach reafon-' 

 ing is fo great a trefpafs on every principle <)f common I'enfe, 

 that to beftow any time on the refutation of it, is, iu fome 

 nieafure, to fall under the fame ceniure." 



Page 17 [. " If any one aflerts, as Mr. De T.uc has done, 

 that fand is a chemical depofit, a certain modi- of cryftalliza- 

 tioti which quart'/, lometimes afl\i:nes, let liiiii draw the line 

 which fej)arate3 fand from gravel; and lit h :n explain why 

 quartz in the form of fand ia not foun.d in mi.'jral veii;s, in 

 granite, nor in bafall ; that is, in none of the utiiations where 

 the appearances of cryflallization are moft jr-.-iicral and belt 

 afccituined." What is nieaiu by a chemical lUf^Jtl, I do not 

 A 4 underllaud; 



