Arrangement of Minerals, 177 



Genus V. Rock-Salt. 

 Tessular. Cleavage hexahedral. Taste saline. Hardness = 2.0 

 Sp. gr. = 2.2 — 2.3. 



1. Plexahedral Rock-Salt. 



** Salts of Potash. 

 Genus VI. Nitre, or Nitrate of Potash. 

 Prismatic. Taste cooling and saline. Hardness = 2.0. Sp. gr. 

 1.9 — 2.0. 



1. Prismatic Nitre. 



Genus VH. Sulphate op Potash. 

 Cleavage imperfect. Taste disagreeably bitter, but feeble. Hard- 

 ness = 2.5 — 3.0. Sp. gr. = 1.73. 

 1 . Prismatic Sulphate of Potash. 



*■"* Salts of Ammonia, 

 Genus VIII. Sal-Ammoniac. 

 Tessular. Prismatic. Taste pungent and urinous. Hardness 

 =^ 1.5 — 2.5. Sp. gr. = 1.5 — 1.73. 



1 . Octahedral Sal-Ammoniac, or Muriate of Ammonia. 2. Prismatic 

 Sal- Ammoniac, or Sulphate of Ammonia. 



ft Earthi/ Salts, 

 * Salts of Magnesia, 



Genus IX. Epsom Salt or Sulphate of Magnesia. 

 Prismatic. Cleavage perfect. Taste bitter and saline. Hardness 

 = 2.0 — 2.5. Sp. gr. = 1.7 — 1.8. 

 1. Prismatic Epsom Salt. 



** Salts of Alumina, 

 Geiius X. Alum. 

 Tessular. Taste sweetish, astringent. Hardness =2.0 — 2.5. 

 Sp.gr. = 1.7 — 1.8. 

 1. Octahedral Alum. 



-H Compound Salts. 



Genus XI. Glauberite. 

 Prismatic. Hemiprismatic. Taste saline and astringent or bitter, 

 but feeble Hardness = 2.5 — 3.5. Sp. gr. = 2.75 — 2.85. 



1. Hemiprismatic Glauberite. 2. Prismatic Glauberite or Polyhallite. 

 *•** Metalliferous Salts. 

 Genus XII. Vitriol. 



Prismatic. Hemiprismatic. Tetartoprismatic. Streak white. 

 Taste astringent. Hardness = 2.0 — 2.5. Sp. gr. = 1 .8 — 2.3. 

 vol. XXXI. no. LXI, JULY 1841. M 



