I 



[ 247 ] 



tallization of the calcareous earth, the greater part of which being 

 much more foluble than the other earths, ftill remained in fo- 

 lution after the others had for the moft part been depofited. 

 This explains why many of thefe primitive calcareous maffes are 

 of all others the freeft from foreign admixture. In feme few 

 inftances however it muft have happened that the calcareous parti- 

 cles intermixed with other earths were faturated before the reunion 

 and depofition of the other earths, and hence in fome countries 

 ftrata of primitive calcareous maffes occur in the midft of gneifs, 

 or alternating with it ; but thefe inftances are very rare. 



That the formation of fixed air was an event fubfequent to the 

 formation of moft of the primaeval ftones, appears from the obfer- 

 vation, that the calcareous earth found in the compofition of pri- 

 maeval ftones is in a cauftic ftate. 44 Roz. 206. 



The immenfe maffes concreted and depofited on the interior 

 nucleus of the earth formed the primitive mountains. It may 

 perhaps be tlibught that this depofition fiiould be equally diffufed 

 and fiiould conftitute only an even cruft over this interior nucleus, 

 but fuch a difpofition is contrary to the nature of cryftallization, 

 between whofe fiioots an interval always intercedes, if not too 

 fudden. The water firft difcharged of its diffolved contents, and 

 thereby heated, moved upwards, being preffed by the circumam- 

 bient denfer fluid, which was too heterogenous to mix with, and 

 be diluted by it. The depofit already formed affording to the 

 fucceeding portions of the charged fluid a bafis whofe points of 



contadl 



