DESCRIPTIVE MINERALOGY. 



CLASS I. 



GASEOUS MINERALS. 



These substances are sometimes found in a free state ; at others they are held in solution 

 by water, under pressure, but are given out when the pressure is relieved. Some of them 

 burn upon the application of a lighted taper ; others do not. 



ORDER I. COMBUSTIBLE GASES. 



There are four of these combustible gases which have been found in nature, viz : 



1. Hydrogen. 3. Sulphuretted Hydrogen. 



2. Carburetted Hydrogen. 4. Phosphuretted Hydrogen. 



HYDROGEN. 



IFrom the Greek uJup, water, and ysvvotu, / generate ; because it is a constituent of water.] 



Hydrogen Gas. Cleaveland. — Hydrogen. SAepard and Dana. — Raines Hydrogen-Gfas. Mohs. — Hydrogene. 



BevAant. 



Description. Gaseous, colourless, inodorous, and transparent ; absorbed by water in very 

 small quantity. It is the lightest substance known, its specific gravity being 68.8, compared 

 with air at 1000.0. 



This gas bums with a feeble flame when in contact with the atmosphere, but it extinguishes 

 burning bodies. When mixed with oxygen and fired with a lighted taper or with the electric 

 spark, it explodes violently, and the result is the formation of water. 



