a Lake of Bitumen In Trinidad. 67 
a turtle. Its more common confidence and appearance is that 
of pit-coal, the colour rather greyer. It breaks into fmali 
fragments, of a cellular appearance and glofiy, with a number of 
minute and fhining particles interfperfed through its fubftance ; 
It is very friable, and, when liquid, is of a jet black colour. 
Some parts of the furface are covered with a thin and brittle 
fcoria, a little elevated. 
As to its depth, I can form no idea of it ; for in no part could 
I find a fubftratum of any other fubftance ; In feme parts I 
found calcined earth mixed with it. 
Although I imelt lulphur very ftrong on palling over 
many parts of it, I could difcover no appearance of it, or "any 
rent or crack through which the fleams might iffue ; probably 
it w r as from feme parts of the adjacent woods : for although fill* 
phur is the bafis of this bituminous matter, yet the fmells are 
very different, and eafily diftinguifhed, for its fmell comes the 
neared to that of pitch of any thing I know. I could make 
no impreffion on its furface without an axe : at the depth of a 
foot I found it a little fefter, with an oily appearance, in fmali 
cells. A little of it held to a burning candle makes a biffing 
or cracking noife like nitre, emitting fmali fparks with a vivid 
flame, which extinguifhes the moment the candle is removed. 
A piece put in the fire will boil up a long time without fuffering 
much diminution : after a long time’s fevere heat, the furface 
will burn and form a thin fcoria, under which the reft remains 
liquid. Heat feems not to render it fluid, or occupy a larger 
fpace than when cold ; from which, I imagine, there is but 
little alteration on It during the dry months, as the felar rays 
cannot exert their force above an inch below the furface. I 
was told by one Frenchman, that in the dry feafon the whole 
was an uniform fmooth mafs; and by another, that the ravins 
K z contained 
