IIT. Some Account of the Pitchslake in the Island of Trinidad, 
in two Letters : The first from Samuel Span, Esq.to James Tobin, 
Esq. F., L. S.; and the other from Mr. Tobin to Charles Hatchett, 
Esq. F. R.S. & L.S. ; with Observations by Mr. Hatchett. 
Read April 17, 1804. 
St. Vincent, April 2, 1801. 
DEAR SIR, 
SINCE my last of the 10th ult. I have been down to Trinidad, where 
I devoted one day to the pitch-lake, to procure from thence the 
different specimens you wished for. They are on board the 
Union-Island, and I hope will arrive safe, and in good order. 
I have packed them in two barrels, and delivered them to the 
care of the captain for you.. The first consists of pebbles pick- 
ed up from the landing-place on the beach, and pieces broken 
from the rocks on the sea-coast, partly below the surface of the 
.sea, and partly from the same rocks above high-water mark ; but 
the whole appears to be of. the same nature with that of the lake. 
The other barrel contains, in separate parcels—a kind of pitch- 
cinder, which is found in great abundance on the borders of the 
lake—firm pitch from one side of the lake—pitch from the body 
of the lake—and pitch taken from the crater of a tumulus rising 
about two feet above the level of the ground around it, and di- 
stant from the lake about a hundred yards: this last is by 
much the freshest, and indeed appeared but just thrown up, and 
consists of about half of the whole quantity in this spot, e 
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