194 
On certain Varieties 
Oxygen. 20 
Nitrogen. 9’2 
Geological situation. —It occurs in beds of 2 or 3 feet 
in thickness ; its series is composed of alternate beds of 
sandstone and clay ; the latter rock, of blackish grey 
colour, with impressions of ferns and Equiseta , composes 
the floor and the roof of the seam. 
RICHMOND, TASMANIA. 
Slaty Glance Coal. {Jamieson.) 
(Syn.—A nthracite, Brongniart.) 
External character. —Colour bluish steel grey, texture 
foliate, fracture slaty, frangible, sometimes composed of 
brilliant laminae, variously arranged ; specific gra¬ 
vity 1*75. 
Chemical character. —It burns with difficulty, yields 
little or no flame, nor any bituminous odour; its prox¬ 
imate constituents are— 
Charcoal . 60*0 
Lime. 20*0 
Alumine . 10*0 
Peroxide of iron. 3*5 
Water . 6*5 
Magnesia undetermined. 
Applied to the production of gas, one pound gives 
1032 cubic inches of very feeble illuminating gas. No 
coke or tar were obtained in the process. 
The gaseous mixture contains in each 100 volumes— 
Sulphuretted Hydrogen. 10* 
Carbonic acid. 25* 
Other inflammatory gas . 65* 
Analysed with peroxide of copper, the quantities of its 
ultimate elements, abstracted from earthy matter, stand 
in the following proportion :— 
