528 INQUIRY INTO THE STRENGTH 
. 
constituents, the analysis being a mean of experi- 
ments on a large quantity : 
Silextesrescoctet sited tearcaseoreoncetes 58.4 
FA Vimmmnma eee. ee Bon ce nnse tees cst 40.0 
Gime bets Assesses wel sete ek 1.6 
100.0 
M. Robin gives the depth of the beds as 
varying from five to twenty-one yards: the coal isa 
perfect black, has a slight metallic lustre, and its 
fracture is conchoidal, when made in the mass.— 
Its density is very great, and by reason of its 
great compactness, it kindles with difficulty, and 
consumes slowly. 
The same properties are observable in the 
analysis of the Welsh, and also of the American 
anthracites, all of which exhibit peculiar features, 
as to their density, and their resistance to com- 
bustion. 
These coals will pass through a smelting fur- 
nace, exposed to intense heat, for a period of 48 
hours, with no other apparent change than their 
surfaces being slightly calcined. When these 
specimens are broken, the interior fractures 
exhibit the same black lustre as is observable in 
the raw material. 
