DESCRIPTIVE MINERALOGY. 



CLASS I. 



GASEOUS MINERALS. 



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

 hy vjater, 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. 



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



1. Hydrogen. 3. Sulphuretted Hydrogen. 



2. Carburetted Hydrogen. 4. Phosphureited Hydrogen. 



HYDROGEN. 



IFrom the Greek u5wp, water, and yjvvau, I generate ; because it is a constituent of water.] 



Hydrogen Gas. Clcavdand. — Hydrogen. Shepard and Dana. — Rcines Hydrogen-Gas. Muhs. — Hydrogi-ne. 



Bcudant. 



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

 small quantity. It is liie ligiitest substance known, its specific gravity being 68.8, compared 

 with air at 1000.0. 



This gas burns witii a feeble tlamc when in contact with the atmosphere, but it e.\tinguishes 

 burning bodies. When mixed witii oxygen and tired wilii a lighted taper or witli llio electric 

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



