{ 66 ) 



finity of points which, viewed through the 

 lens, are difcovered to be fo many minute 

 tetrahedral prifms, diftindly defined. On 

 breaking the fpheres we perceive that the 

 prifms arc continued within them, and, be- 

 coming thinner, proceed to the centre ; or, 

 to fpeak more properly, we find that the 

 fpheres are only the refult of a number of 

 prifms joined together length wife. The 

 portion of the prifms that is immerfed 

 within the fpheres is opake ; but that part 

 which projects out has a degree of tranf- 

 parency. It is to be obferved, that though 

 the greater number of thefe minute fpheres 

 are perfedly folid, many of them have a 

 round vacuity at the centre, fometimes ex- 

 tending to one tenth part of the whole 

 fphere. 



This zeolite Is the fofteft of all the fpecies 

 hitherto enumerated, and may be fcraped or 

 cut with a knife. 



The fixth, and laft, fpecies is one of the 

 moft beautiful zeolites hitherto difcovered 



by 



