ORDER IV. GENERA AND SPECIES. 405 



Cleavage, P + w = 120. Somewhat more distinct 

 Pr + co. 



Nitre. ii. 34. 



IV. ROCK-SALT. Tessular. 



Taste saline. 



H. = 2-0. 



G. = 2-2 ... 2-3. 



1. HEXAHEDHAL. Tessular. 

 Cleavage, hexahedron. 



Hexahedral Rock-Salt. J. ii. 36. 



V. AMMONIAC-SALT. Tessular. 



Taste saline, pungent. 

 H. = 1-5 ... 2-0. 

 G. = 1-5 ... 1-6. 



1. OCTAHEDRAL. Tessular. 

 Cleavage, octahedron. 



Octahedral Sal Ammoniac. J. ii. 39. 



VI. VITRIOL-SALT. Prismatic. 



Taste astringent. 

 H. = 2-0 ... 2-5. 

 G. = 1-8 ... 2-3. 



M 



1. HE MI-PRISMATIC. Hemi-prismatic. = 101 35'. 



Inclination = 14 20'. 

 Cleavage, P oo. Somewhat less distinct, P + co = 



82 21'. Inclination of P co on P + oo = 99 23'. 

 Colour green. 

 H. = 2-0. 

 G. = 1-8 ... 1-9. 



Green Vitriol. J. ii. 41 



