Arrangement of Minerals, 175 



CLASS III. 

 Inflammable Minerals. 

 Order I. Resin. Order II. Coal. 



CLASS I. . 

 Characters of the Class. — If solid, is sapid. Specific gra- 

 vity less than 3.8.* 



Order I. GAS. 

 Elastic. Not acid. Sp. gr. — 0.0001 — 0.0014. 



Genus I. Hydrogen Gas. 

 Evident smell. Sp. gr. = 0.0001 — 0.0014. 

 1. Pure Hydrogen Gas. 2. Carbiiretted Hydrogen Gas. 3. Sulphu- 

 retted Hydrogen Gas. 4. Phosphuretted Hydrogen Gas. 



Genus II. Azotic Gas. 



Without snjell or taste. Sp. gr. = 0.9757. 



1. Common Azotic Gas. 



Genus III. Atmospheric Air. 

 Without smell or taste. Sp. gr. z= 0-001 — 0001 5. 



1. Pure Atmospheric Air. 



Order II. WATER. 

 Liquid. Tasteless, or with sensible smell and taste. Sp. 

 gr.:^ 1.0 — 1.0269. 



Genus I. Atmospheric Water. 

 W^ithout smell or taste. Sp. gr. = 1.0. 

 1. Pure Atmospheric Water. 



Genus II. Sea-Water. 

 Sensible smell and taste. Sp. gr. = 1.0269. 

 1 . Common Sea- Water. 



Order III. ACID. 

 Elastic, liquid, and solid. Hardness= 0.0 — 1.5. Sp. gr. = 

 0.0018—3.7. Taste acid, sweetish. 



* This class might be divided into subclasses, the first subclass to include 

 the Gases, the second the Waters, the third the Acids, and the fourth the 

 Salts ; but the number of substances in the class is so inconsiderable, as to 

 render the introduction of such subdiyisions unnecessary. 



