46 Geology of Massachusetis. 
cite, geological considerations confirm the results of experiments. 
Baron Humboldt, who has probably seen more of the rocks of 
the globe, than any man living, remarks, that ‘‘ anthracite is a 
more ancient formation than coal, and a more recent formation than 
graphite, or carburetted iron. Carbon becomes more hydrogenated, 
in proportion as it approaches the secondary rocks.” ‘This last sen- 
tence, divested of its technical obscurity, means, if I understand it, 
that the newer the rock in which the carbon is found, the greater will 
be the quantity of hydrogen combined with it: and we know that an 
increase of hydrogen, will render coal more combustible. Now if 
I am correct in the opinion, that the Worcester anthracite is contain- 
ed in older rocks than that in Rhode Island, and the anthracite of 
Pennsylvania, in rocks still newer than those of Rhode Island, 
we might expect, that the newer would prove the best for fuel, 
and the older the poorest, because containing the least hydro- 
gen. ‘The quantity of carbon, however, in the Worcester coal, 
is believed to be nearly as great, as in that from Rhode Island 
and Pennsylvania; although no analysis has been made of the for- 
mer. But carbon is less combustible than hydrogen. Yet1 can 
hardly believe, that a coal, which contains probably not less than 
90 per centum of carbon, should not be employed, in some way or 
other, as valuable fuel. 
The formation which I have denominated gray wacke, and which 
contains the anthracite in Rhode Island, extends northerly in interrup- 
ted patches, nearly across the whole of Massachusetts; as may be 
seen on the Map. ‘The most southern patch, embraces nearly the 
whole of Bristol and part of Plymouth county: the second ex- 
tends from Wrentham to Dedham: the third includes several towns 
in the vicinity of Boston; and the fourth is in Rowley and Newbury 
in Essex county. 1 know of no reason, why one part of this forma- 
tion should contain anthracite rather than another: and hence we 
may reasonably look for it in any part of the graywacke formation, 
exhibited onthe Map. ‘The transition mica slate, containing the Wor- 
cester anthracite, occupies, as the Map will show, a large portion of 
the northeastern part of the state ; and it would not be strange, if oth- 
er beds of that mineral] should be found in it. 
Graphite, Plumbago, or Black Lead. 
This substance has the color of lead, leaves a trace like that metal 
upon paper, and bears the common name, black lead; butit contains no 
lead. Itis composed of above 90 per centum of carbon, and the rest is 
