26o 



ILLUSTRATIONS OF THE 



which of the two fpecies they ought to be re. 

 ferred. 



Note xiv. § 75, 



On Wbinjiofie, 



234. To the fads and reafonings given above, 

 I fhall, in this note, add a few remarks, tending 

 to fhew, that whinftone is not of volcanic, nor 

 of aqueous, but certainly of igneous origin. 



It is afferted (§ 62.), that carbonat of lime and 

 zeolite ar6 often contained in vvhinflone, but :.e- 

 ver in lava, and that this circumftance may fome- 

 times ferve to diilinguifh thefe flones from one 

 another. With refpe6l to carbonat of lime, in par- 

 ticular, it feems evident, that this fubftance can- 

 not enter into the original compofition of any la- 

 va, becaufe the fame heat which melted the lava, 

 would, w4iere there was no greater preffure than 

 the weight of the atmofphere, expel the carbo- 



nic acid and produce quicklime. 



Notwithftand- 



ing this, rocks, containing carbonat of lime, have 

 often been confidered as lavas, into the pores 

 and cavities of which, calcareous matter having 

 been carried by the infiltration of water, had 



r 



cryllallized into fpar. Thus Spallanzani, 



in 



