Inflammables, 
tains, and ftrata over coals and iron-ore ; it is alfo found 
in frnall flatted fpherical maffes, containing fmall particles 
of fulphuret of iron in the form of pyrites. Colour black, 
gives a dark-grey ftreak, adheres a little to the tongue ; tex¬ 
ture flaty, fometimes ftraight, fometimes curved, and has 
a fweetilh and fomewhat aftringent tafte, and is apt to 
wither in the air into a dull grey powder. It is ufed in 
alum-works. 
10. Alumen turfae, or turf-alum: not emitting va¬ 
pours when fulphuric acid is poured upon it; mixed with 
turf. Found near Elflmburg in Sweden, and in France; 
and conflfts of turf fo impregnated with fulphuret of iron 
as to yield a fmall portion of alum. 
CLASS III. INFLAMMABLES. 
Thofe fubftances which are called inflammables are not 
all capable of producing flame ; fome Amply become red- 
hot when expofed to the neceffary degree of heat; and 
infenflbly confume without the phenomena that uiually 
attend the procefs of combuflion. If expofed to a red 
heat in a veflel from which atmofpheric air is excluded, 
they are in many inltances decompofed ; and at the fame 
time their elementary conftituent principles form either 
new or differently-modifled compounds ; thefe are for the 
moll; part volatile, and pafs away in the form of water, 
and of oil or bitumen, and different aeriform fluids. 
That which remains in the veflel conflfts of earthy and 
metallic matter, and charcoal. If this reftduum be ex¬ 
pofed to a red heat in the open air, the charcoal combines 
with the oxygen or pure part of the atmofphere, and forms 
carbonic acid gas, or fixed air; which is diflipated, leav¬ 
ing only the earthy and metallic matter. The products 
of the analyfis of inflammable minerals are for the moft 
part—Inflammable air, or hydrogen gas ; heavy inflam¬ 
mable air, or carbonated hydrogen gas ; fixed air, or car¬ 
bonic acid gas ; water; oil, or bitumen ; and charcoal. 
Thefe fubftances appear to be ultimately derived from 
the following three elementary principles: i. Carbon, or 
the bafe of charcoal. 2. Oxygen, or that part of atmo- 
fpherical air which fupports combuftion ; called oxygen, 
becaufe it appears to be the acidifying principle. 3. Hy¬ 
drogen, or the inflammable principle; called hydrogen, 
becaufe when united with oxygen it conftitutes water.—■ 
The chief and moft ufeful of the inflammables is 
Bitumen, including Naphtha, Tar, Coal, &c. — Ge¬ 
neric characters : Eafily combuftible with flame, and 
emitting when ignited a ftrong odour; greafy to the touch. 
Some of the products refulting from the diftillation of 
common coal, fays Dr. Kidd, very clofely refemble the 
bituminous fubftances called naphtha, petroleum, and 
afphaltum. If therefore we fuppofe a diftillation of coal 
to be going on in the interior of the earth, the production 
of the different natural forms of bitumen may thus be ac¬ 
counted for; as alfo the exiftence of that variety of coal 
to which culm and Kilkenny coal belong ; which, by the 
diftillation here fuppofed, may have been deprived of 
their bitumen. No ftrefs is intended to be laid on this 
hypothefis further than as it ferves for the convenience 
of arrangement; for, thus having traced the formation 
of bitumen through its various ftages, and fhown, in 
fome inftances at leaft, its neceffary connexion with vege¬ 
table matter, we leem enabled to account for its prefence 
in a feparate and infulated ftate. 
1. Bitumen naphtha, fluid bitumen, or naphtha. Spe¬ 
cific charaClers ; it is fluid, nearly colourlefs, volatile, and 
highly inflammable. Naphtha is met with abundantly in 
Perfia and Media, iffuing from rocks and clays. It has 
alfo been found, according to Mr. Kirwan, at Mont Feftin, 
near Modena, in Italy. The fpecific gravity of naphtha 
is ’729 to ‘84.7, lefs than that of the moft highly rectified 
fpirit of wine. By expofure it lofes its transparency and 
odour; acquires a yellowifh, or even brown, colour; be¬ 
comes thicker, and fpecifically heavier; and approaches in 
its charaCfers to the next fpecies, petroleum. In various 
parts of Perfia naphtha is ufed inftead of oil for lamps, &c. 
Inflammables. 475 
2. Bitumen petroleum, petroleum, or rock-oil: liquid, 
but of a thicker confidence than the laft, and not fo tr mf- 
parent; coloured. This is found on the furface of cer¬ 
tain fprings in Perfia, Media, and Siberia; or in coal-miner, 
or oozing out of rocks and mineral beds, in various parts 
of Great Britain, and of Europe in general. It is of a 
thicker confidence than naphtha, and a rather lefs plea- 
fant fmell, is lighter than water, but heavier than alcohol; 
fpecific gravity -878. Colour yellow, or with a fhade of 
red, green, browniih, or blackifli; when burnt it yields a 
foot, and leaves a fmall quantity of coaly refiduum. By 
expofure it becomes of the confidence of treacle. 
3. Bitumen maltha, or mineral tar: infpiflated, black, 
flicking to the fingers. Found in Colebrook-dale and 
other coal-counties in Britain, fometimes floating on 
lakes in Paleftine, Babylon, Arabia, Perfia, China, Bar- 
badoes, and various parts of Europe, and frequently 
ifluing from rocks ; is of the confidence of treacle, of a 
blackilh-brown colour, opake, and has a very ftrong fmell 
when burnt; it feems to have its origin from the former 
fpecies, which, by long expofure to the air, has loft its 
volatile particles, and obtained a thicker confidence. 
Specific gravity, it. 
4. Bitumen mumia, or mineral pitch: black, inodorous, 
foftening in a low heat. Found in Perfia, in the cliffs of 
rocks at Chorafibu, on the river Caucafus ; and is faid to 
have been difcovered in Lancafhire. Colour blackilh- 
brown, foft'and tough like cooler’s wax when the weather 
is warm, but brittle like pitch in cold weather : it does 
not ftain the fingers, and on a hot iron flames with a ra¬ 
ther ftrong odour, and leaves a quantity of allies. The 
Perfians value it highly; and, after mixing it with about 
a third part of wax, apply it to frelh wounds. 
By an article in Ede’s Journal, publilhed at Philadelphia 
under the title of The Portico, we collect that judge 
Cooper (formerly of Manchefter) has taken much pains 
to introduce gas-lights into the United States; and, it ap¬ 
pears, with fuccefs. But, as coal is dear in America, and 
as an incorrebl notion appears to be formed that coal-gas 
is unavoidably oftenfive in its fmell, Dr. Kugler, of Phi¬ 
ladelphia, has manufactured gas from pitch, “ an article 
which can, in America, be every-where procured ; and 
from which, by a Ample apparatus, eafily managed with¬ 
out any thing oftenfive in the operation, he prepares a 
gas at once cheaper and more brilliant than that prepared 
from coal.” Pitch, rofin, and even oil of turpentine, are 
faid to anfwer equally well. In Dr. Kugler’s apparatus, 
“ the oil condenfed in the receiver, immerfed in water for 
the purpofe, is afterwards employed to diffolve the pitch, 
which, thus dilfolved, defcends in a liquid form through 
an aperture, regulated by a ftop-cock, down to the hotted 
part of the red-hot retort, and is there decompofed and 
afcends into the gas-holder, after efcaping from the con¬ 
densing receiver. In this way the gas requires no walk¬ 
ing in lime-water; and no noxious vapour is produced.” 
The ancients had a wine impregnated with the virtues 
of liquid pitch or tar : it was called pijfites, from ’m.crccc., 
pitch. To prepare it, the tar was ordered to be walhed 
in fea-water or brine, and afterwards in frelh water many 
times ; and, after a tedious preparation of this kind, two 
ounces of it were ordered to be put to eight gallons of 
mud, which is to be fuftered to work together, and the 
clear liquor to be bottle off. This was accounted a warm 
wine, very afliftant to concofilion, and of an abfterfive fa¬ 
culty, and a good peftoral; on thefe accounts it was 
given in diforders of the breaft, and in obftru&ions of the 
liver, lpleen, and uterus, if not attended with a fever; 
and was a common medicine in coughs and afthmas of all 
kinds. 
5. Bitumen afphaltum, or afphaltum : opake, fhining, 
black or brownilh-blacL eafily melting in heat, effervef- 
cing with concentrated nitric acid. Found abundantly 
in various parts of Europe, Afia, and America ; elpeci- 
ally in the iftand of Trinidad, in a plain called Turlane, 
where it covers the furface of the earth for a confiderable 
diftance. 
MINERALOGY. 
