164 TT. Sterry Hunt on the Chemical and Geological History 
fracture, and flies into fragments when exposed to heat, For 
the rest, it varies considerably in its chemical characters. The 
mineral from Acton, which is much harder and more metallic 
looking than that from the other localities, gives off, when heat- 
ed to redness in a close vessel, a portion of water, but no inflam- 
-mable gas or vapor, and loses 69 per cent of its weight, leaving 
a carbon which is difficult of combustion, and gives, when in- 
cinerated, 2:2 per cent of ash. Like the specimens described 
y Vanuxem, it approaches to anthracite in its characters. That 
from the other localities examined gives off when heated @ 
greater or less proportion of combustible vapor, which condenses, 
in part, into a tarry liquid, having an offensive odor very dis- 
tinct from the product of the distillation of coals or pyroschists. 
Carefully selected specimens yield, by incineration, only a few 
thousandths of ash, apparently due to accidental impurities. In 
a specimen from Quebec the volatile matters equalled 19'5 per 
cent; in one from Orleans Island 21:0; in one from St. Flavien 
15:8, and in another, six miles from the last, 245 percent. The 
latter, when exposed to heat, swells up, and leaves a porous 
coke, the fragments cohering like those of a caking coal. The 
same is true, to a less extent, of that of Orleans. These matters 
are not affected by benzole, with the exception of the last men- 
tioned, which appear to contain a small amount of soluble sub- 
stance. The mode of occurrence of these matters shows that they 
have once been in a liquid state, and, as the limestones of this 
group are in many parts distinctly bituminous, there can be 
- little doubt that the liquid carbonaceous matter was bitumed, 
which has since been slowly oxydized, indurated, and converted 
into these insoluble, infusible coaly and anthracitie bodies. 
This view is confirmed by the examination of a bitumen whieh 
appears to be in the very act of changing. In the Devonian 
limestones of Canada, there are beds of fossil corals, which are 
impregnated with petroleum, At the outcrop of these, where 
the strata have been for ages exposed to the weather, the pet 
leum is replaced by a black matter, which lines the cells, and, 
having lost its oily character, no longer repels the water like the 
still oily corals within. Benzole, which readily dissolves the bitu- 
men from these, does not affect the black color of the weathe 
corals. A fragment of a Favosites impregnated with this black 
matter was crushed and treated with dilute muriatic acid, wh! 
removed the carbonate of lime of which the coral was composed; 
_and left five per cent of a brownish-black residue, This, when 
nosed to heat, burned with flame, without melting, and left. a 
bulky coherent coaly residue, which gave a little ash. hen 
treated with a large amount of boiling benzole (coal-naphtha) 
the residue gave up only 16°5 per cent of soluble bitumen, and 
the subsequent analysis of the insoluble residue gave volatile 
