

HUTTONIAN THEORY. 



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6^. But, in order to fee whether this hypo- 

 thefis will explain the diverfity of the two fub- 

 ilances, without which it will not be entitled 

 to much attention, we mufl remark, that the 

 prefence of carbonat of lime in a body that has 



been fufed, argues, agreeably to the principles 

 formerly explained, that the fufion was brought 

 about under a great comprefling force, that is 

 to fay, deep in the bowels of the earth, or in the 

 great laboratory of the mineral regions. We 

 ^re, therefore, to fuppofe that the fufion of the 

 whin was performed in thofe regions, where the 

 compreflion was fufficient to preferve the car- 

 bonic gas in union with the calcareous earth, 

 fo that thefe two fubflances melted together, 

 and, on cooling, cryftallized into fpar. In 

 the lavas, again, thrown out by yolcanic erup- 

 tion, the fufion, as we know, wherever it may 

 begin, continues in the open air, where the pref- 

 fure is only that of the atmofphere : the calca- 

 reous earth, which, therefore, may have been, 

 in the form of a carbonat, among the materials 

 of this lava, mult be converted into quicklime, 

 ^nd become infulible ; hence the want of calca- 

 reous fpar in lavas that have flowed at the fur- 

 face. 



Thus, whinflone is to be accounted a fubter- 

 raneous, or un-erupted lava ; and our theory has 

 the advantage of explaining both the affinity 



and 



E3 



