530 INQUIRY INTO THE STRENGTH 
In speaking of No. 1, specimen, Mr. Johnson 
describes it as a compact structure, giving 
conchoidal fractures in all directions, apparently 
indifferent to the surface of deposition, which are . 
manifested only by alternating lines or seams of 
bluish black, and jet black, which mark the suc- 
cessive layers. He states the appearance to give 
the idea, that the surfaces have been in a great 
measure obliterated, while the whole mass was, 
from some cause, in a semi-fluid state. The 
specific gravity is stated at 1.591 or 99% lbs. to 
the cubic foot. 
No. 2, specimen, experimented upon by Pro- 
fessor Johnson, gave a specific gravity of 1.574, 
or 983 lbs. to the cubic foot, and yielded 85.909 
per cent. of carbon. 
No. 3, specimen, was found to have a specific 
gravity of 1.55 or 963% lbs to the cubic foot ; and 
carbon, not volatile at a white heat, equal to 
90.705 per cent. 
The above analysis not only shows the compo- 
sition of this description of fuel, but exhibits the 
density and compactness of its structure. It also 
affords evidence of its fitness for the smelting 
