1 



lej,,^ HUTTONIAN THEORY. 



\ 



I 



* 



bv ;.,! 



le 



no ii 



3t accr: 



Teiiiti 

 cleark 



time It: 



are 



ot i^? 



e/ 



^ 



^^9 



as may be fuppofed, confiderably irregular. Ei- 

 ^^ ^y^ ther of thefe terms being derived entirely from 

 te|. external characters, has the advantage of in- 

 'CisL volving nothing theoretical. 

 her I The lenticular veins are certainly not formed 



•Sric|; 1^^^ ^^^ ^^'^^^ mineral veins, by injedion, fxnce 

 sftic! they are (hut in, on all fides, by the folid rock. 

 ^ercoljc When they are fbund, therefore, in Gratified 



rocks, fach as have not themfelves been melted 



'^ 



muft conceive them to be compofed of 



fufible than the furrounding 



m 



ey 



fo that they have been brought into fufion by a 

 degree of heat which the reft of the rock was 

 able to refift, and, on cooling, have allumed a 

 fparry ftrudure. When they are found in 

 rocks, of which the whole has been fluid, they 



^' ' muft be confidered as component parts of that 



mafs, which, by an ekaive attradion, have 



Iiinfi-:^ united with one another, and feparatec 



nhij felves from the fubrtances to which tl 



\0 lefs affinity. 



m¥ The veins of this kind feem to be conncded 



bel with thofe called in Derbyftiire Fhe V 



which the ores of metals are fometimes found. 

 ^^f':' The pipe veins, indeed, are not in all caies com- 

 pletely infulated, but fometimes communicate 

 with the veins properly called mineral. I am 

 too little acquainted, however, with their natu- 

 ral hiftory, to be able to fay with certainty to 

 \ R 2 w^hich 



m 



t 



