476 Inflammables. MINERALOGY. Inflammables. 
diftnnce. Its furface is bard, black, ihining, and refmous: 
it eaiily melts before the dame of a candle, and may be 
ufed for the fame purpofes as fealing-wax. When pure, 
it burns without leaving any allies ; when hardened, is 
very brittle ; and was uied. by the ancient Egyptians for 
making mummies; when difiolved in oil, it is ufed as a 
varnifh for leather and other purpofes. 
The word afphaltum is derived from the name of the 
lake in Judaia, where this fubftance occurs in great abun¬ 
dance. It frit riles in a liquid form to the furface of the 
water, and there hardens. It differs from the foregoing 
fpecies principally in confidence. Klaproth analyfed a 
variety of afphaltum from Avlona in Albania, the l'pe- 
cific gravity of which was i'z. He fays that it burns 
with a ftrong and lively flame ; and is confidered as the 
principal ingredient in the Greek fire fo much employed 
in former times. Afphaltum may be diftinguilhed from 
coal by the l'mell it emits when rubbed. It is, befides, 
eledlric ; which coal is not. It is diltinguilhed from jet 
by its brittle,nefs, and by its peculiar odour when rubbed. 
See Asphaltites and Asphaltum, vol. ii. 
The exiftence of an expanfe of mineral pitch, fuffici- 
ently extenfive to merit the appellation of a lake, is a cir- 
cumftance fo very remarkable, that it will not be deemed 
improper to infert an authentic account of the bituminous 
lake of the ifland of Trinidad. A'del'cription of this ce¬ 
lebrated pitch-lake was firlt given by Mr. Anderlon, in 
the Philofophical Tranfadiions for 1789 ; and fome no¬ 
tices relative to it were communicated by Mr. Tobin, in 
the eighth volume of the Linnsean Tranfadtions ; but we 
now polfefs a more complete account of it by Dr. Nugent, 
who vifited it in Odlober 1807, and wliofe memoir is pub- 
lillied in the firft volume of the Tranfadtions of the Geo¬ 
logical Society. 
The pitch-lake of Trinidad, by the French called La 
Braye, is fituated on the north fide of the Gulf of Paria, 
on the high point La Braye, a confiderable head-land prin¬ 
cipally compofed, at its fouthern fide, of a kind of porce¬ 
lain jafper. It is not ealy to ftate precifely the extent of 
tliis colledlion of pitch, the lines between it and the 
neighbouring foil not being always well defined ; and in¬ 
deed Dr. Nugent fuppoles it to form the fubftratum of the 
furrounding tradf of land. It may, however, be laid, that 
it is bounded on the north and weft fides by the lea, on 
the fouth by the juft-mentioned rocky eminence of por¬ 
celain jafper, and on the eaft by the ufual argillaceous 
foil of the country ; the main body may, perhaps, be efti- 
mated at three miles in circumference ; the depth cannot 
be afeertained, and no fubjacent rock or foil can be difco- 
vered. That part of this expanfe, which may properly 
be called a lake, is fituated higher than the adjoining land, 
and you defeend by a gentle Hope to the fea, where the 
pitch is much contaminated by the land of the beach. 
On approaching the lake, a ftrong fulphureous and 
pitchy lrnell is perceived ; and, on a nearer approach, the 
bituminous plain itfelf opens to the view, appearing at 
firft light to be an expanfe of ftill water, frequently in¬ 
terrupted by clumps of dwarf-trees, or diets of rulhes 
and lhrubs. Dr. Nugent was fo ftruck by the fingularity 
of the feene, that it was feme time before he could re¬ 
cover from his furprile fo as to inveftigate it minutely. 
The furface of the lake is of the colour of allies ; and, at 
the feafon when this traveller vifited the lake, not fuffi- 
ciently Imooth to be flippery ; it was not adhelive, though 
it received the impreftion of the foot, and the confluence 
was fuch as to bear the travellers without any tremulous 
motion whatever ; but in the dry fealon the lurface is pro¬ 
bably in a ftate approaching fluidity, as is fhown by pieces 
of wood and other lubftances being enveloped in it ; dif¬ 
ferent bodies have been known Howdy to link into it. If 
a quantity be cut out, the cavity left will be Ihortly filled 
up. Numberlefs proofs are given’of its being at times in 
this foftened ftate ; the negro-houfes of the vicinage, for 
jnftance, built by driving polls in the earth, frequently 
41 re tw illed or funk on one fide. In many places it leaps 
to have actually overflowed like lava, and prefents the 
wrinkled appearance which a fluggilh fubftance would ex¬ 
hibit in motion. 
This bituminous plain is interfered by numerous in¬ 
terlaces or chafms, filled with water in the wet feafon; 
they are generally deep in proportion to their width, fome 
being only a few inches in depth, others feveral feet, and 
many almoft unfathomable. The people of the neigh¬ 
bourhood derive their fupply of water from this fource, 
and refrelh themfelves by bathing in it; the water is per¬ 
fectly uncontaminated by the pitch, and filli are caught 
in it, and particularly a very good fpecies of mullet. 
The arrangement of the chafms is Angular; the fides are 
invariably Ihelving from the furface, fo as nearly to meet 
at the bottom ; but they bulge out towards each other 
with a confiderable convexity. Thele crevices will now 
and then dole up entirely; when marks or feams are left 
behind. 
The bituminous fubftance forming this lake prefents 
different appearances in different fpots. In fome parts it 
is black, with a lplintery or a conchoidal fraCture, of con¬ 
fiderable fpecific gravity, and with little or no luftre, re- 
fembling particular kinds of coal, and fo hard as to re¬ 
quire a fevere blow of the hammer to break it; in other 
parts it is fo much fofter as to be eafily cut with a knife or 
lpade, when the interior appears veficular and oily. In 
one place it bubbles up in a perfeClly-fluid ftate 5 and in one 
of the neighbouring plantations it is faid to occur of a 
bright colour, Ihining, tranfpafent,and brittle, like bottle- 
glafsorrelin. The odour in all tliefe inftances is ftrong, 
and like that of a combination of pitch and fulphur, which 
latter fubftance, however, is no-where to be perceived. 
A bit of the pitch held in the candle melts like fealing- 
wax, and burns with a light flame, which is extinguilhed 
whenever it is removed, and in cooling the bitumen har¬ 
dens again. It may be converted to many ufeful pur¬ 
pofes ; and is, indeed, univerfally uled in the country 
wherever pitch is required. The reports of naval officers 
who have tried it are favourable to its more general adop¬ 
tion ; in which cafe this vaft collection of bitumen would 
afford an inexhauftible fupply of an eflentiai article of 
naval ftores, and, being fituated on the margin of the fea, 
would be wrought and lliipped with little inconvenience 
or expenfe. 
fi. Retinafpkaltuju. —This fubftance is a natural combi¬ 
nation of relin and afphaltum 5 and hence Mr. Hatchett, 
who firft analyfed it, was induced to diftinguilli it from 
other bituminous fubftances by this name. It is met with 
in moderately-fized mafles, among the earthy matter in 
which the ftrata of Bovey-coal are fituated ; but adhering 
to the coal. Its colour is a light ochry brown, and it 
might by the eye be eaiily miftaken for a variety of um¬ 
ber ; but it pofielTes a much higher degree of ■inflamma¬ 
bility. When placed on a heat iron, it melts and burns 
with a bright flame; yielding at firft a fragrant odour, 
which towards the end of the combullion becomes flight- 
ly tainted with that of afphaltum. 
6. Bitumen fevum, or mineral tallow : white, rather 
brittle, floating on water, burning eaiily with a blue flame. 
Found in the maritime parts of Finland in the neigh¬ 
bourhood of Narko, and at the lake Loja ; it is foluble 
in cold olive-oil, and in alcohol if mixed with a little al¬ 
kali : is of the confiftence of tallow, lighter than amber¬ 
gris, and burns quickly, leaving a confiderable refiduum 
of allies. 
7. Bitumen elafticum, elaftic bitumen, or mineral caout¬ 
chouc : brown, folid, elaftic like Indian rubber. Found 
in the lead-mine of Odin, near Caftleton, in Derbyfhire, 
with calcareous fpar. Colour yellowiffi or reddifh-brown, 
fpmetimes paler, and relembling in colour and texture 
fine cork; is very elaftic, and loft enough to be com- 
preffed with the fingers when frelh, but hardens and gets 
rather brittle by long expofure to the atmofphere. It is 
infoluble in ether, alcohol, and oil of turpentine ; but is 
readily diflolved in oil o!i"es; burns with a bright 
flame. 
