C 61 ) 



before mentioned with a thin cruft, thii& 

 forming geodes, which, however, are not 

 cryftallized internally. This zeoUte, which 

 incUnes to a white colour, is more tranfpa- 

 rent than the other, and, from its harJnels, 

 cuts glafsj almoft like rock cryftal. The 

 mineral acids have no effedt upon it, not 

 even when pulverifed, though they convert 

 the former fpecies into a kind of jelly. 

 When melted with the aid of oxygenous 

 gas, it emits a thin brilliant blaze, and is 

 changed, with ebullition, into a vitreous and 

 white globule. 



It Is not unufual to find within thefe 

 zeolitic geodes, plates of very tranfparent 

 fulphate of lime. A hundred grains of 

 this, pulverifed, were put into fix hundred 

 of diftilled boiling water. A folution was 

 obtained, and the oxalic acid precipitated 

 the lime. 



Third fpecies. This confifts of ovoid 

 globules, externally dirty, from an earthy 

 coating, but which internally are extremely 



white. 



