16 On the Serpentine Rocks of Hoboken, N. J. &c. 
These coals will no doubt prove the cheapest, most du- 
— cleanly, and pleasant fuel for warming apartments, as 
as for many other useful purposes.—They are without 
doubt the best for making edge tools. 
I believe that Lehigh Coal at 5s. per bushel is as cheap 
as Virginia at 2s. 9¢.—In a grate or stove, a fire of this coal 
will Jast from twelve to fourteen hours. 
OLIVER EVANS. 
Art. Il.— Observations on the Serpentine rocks of Hoboken, 
an New-Jerse ys and on the minerals which they contain ; 
by Tuomas Nurratt. 
{Read in the Academy of N’ atiiral Sciences of Philadelphia, May 8th, 1821. 
Forwarded in MS. for insertion in this Journal. } 
in pees, to the transition 
of serpentine 
granite on which the city of D ered is foemided, gteete in 
contiguity with a rock, sometimes coarsely granular, ‘formed 
principally of quartz and felspar. Seams of breccia 
of angular fragments cemented together @ 
spar resembling arragonite, and which has been erroneous- 
ly announced as a carbonate ef magnesia, indicate at least 
the partial transition of this serpentine into the surrounding 
ions, or the transfusion of some foreign ingredient in- 
to the rocky mass while yet yielding and capable of easy 
penetration. 
This eee which differs so much in external char- 
acter from the finer diaphanous or nephritic kind of Massa- 
olive. Its specific gravity by Nicholson’s balance was 
2,820. It acquires but a feeble polish, and is commonly 
penetrated i octahedral crystals, said —— 
authority to be chromated iron. Before the blowpipe it 
remains infusible, and by strong calbieialelh Jooses 16 pet 
