Argillaceous Genus. 97 



contain 58,33 per cent, of lilex, 1 7, j of argill, 

 6,66 of lime, and 17,5 of water. 4 Berlin 

 Befcbaft.ip. 330. In general the cryftalized 

 forts contain more water than the amorphous. 

 Mr. Bergman found the zeolyte of Jemptland 

 to contain 1 6 per cent, of calcareous Earth, 

 and that of Fero to contain 25 per cent, of 

 argill, fo that the proportions are very varia- 

 ble. 



SPECIES XIII. 

 Of Volcanic Origin. 



Argillaceous Earth imperfeftly united to 4 

 times its weight of Siliceous, and y of its 

 'weight of Iron. 



Pitch-Jlone> Lava. 



It is of a greyifh, greenifh, black, red, or 

 brown colour, has the glaflfy appearance 

 of a femi-vitrified fubftance, and melts eafily 

 perfe : it often contains fubftances feemingly 

 heterogenous : fome pieces of it do not give 

 fire with fteel, and therefore belong to this 

 genus, others do, and belong therefore to the 

 iiliceous genus. 



According to Mr. WiegkVs analyfU- 1. 1 

 Nev. Endcck) p. 18, 100 parts of i* vontain 



H 65 



