OBSERVATIONS ON BASALT, &C. 171 



to (tone can no way affecl: the great queftion which has fo long 

 divided geologists, about the origin of bafalt; for though it is 

 Synthetically demonftrated that bafalt may be formed by fire, 

 the converfe of that proportion (lands fupported by Strong ana- 

 logical arguments, and its formation by water muft be allowed 

 to beat leaft equally poSSible. How far the probabilities derived 

 from the examination of bafaltic formations may influence the 

 ultimate decision, isan enquiry in which I mall not now engage; 

 though I cannot avoid recalling to my mind, the numerous 

 instances of petrifactions found in bafalt, and, as a counterpoife 

 to that observation, the equally numerous inftances in which 

 the heat emanating from it appears to have indurated flrata, 

 and coaked beds of coal. One remark may be Slated here with 

 propriety, as itarifes immediately from the experiment which 

 has occasioned thefe obfervations. In the ultimate refult of 

 that experiment, the arrangement of the molecules was much 

 more perfecl than in the original rock. It might befuppofed, 

 that a longer continuance of the fui table temperature was af- 

 forded it. This, however, could not be, for the mafs was only Why fo little of 



a few feet long, and a few inches thick ; the fire was only "^"'"ffX. 

 °* ' J appears in the 



maintained a day ; and the whole was cooled in a week. But itmfture of 

 the hill of folid bafalt, from which the fubftance operated upon ° itdit ' 

 was taken, is feveral miles long, and Several hundred feet high ; 

 and, (uppofing it to have been irrupted in a irate of igneous 

 fuiion, it muft have required months, nay years, for its refri- 

 geration. How then comes it, that the procefs of cryftallization 

 is fo little advanced ? How comes the confufion of its texture 

 to indicate the very reverfe of the tranquillity and perfection 

 of arrangement, which may be fairly alfumed as neceiTarily 

 attending the extremely gradual changes of fo immenfe a 

 waifs'? 



This objection admits of being obviated, upon the fuppofition Probably becaufe 

 that, in the proceis of melting, the molecules of the bafalt "^ re formed 

 were decomposed; and that the new ones generated were more difpofed to 

 more difpofed to cryftaliize than thofe whofe place they fup- cry 

 plied. This explanation is in fome degree jufiified, by the 



mined. Neither de Buch nor Dolomieu have been able to con- 

 vince themfelves that the augites werealfo formed in the lava ; but 

 I confefs Hiyfslf entirely unable to appreciate the cogency of their 

 arguments, which feem annihilated by the admiiEon they have made 

 m favour of leucites, 



total 



