ORGANIC REMAINS OF A FORMER WORLD.

AN

EXAMINATION OF THE MINERALIZED REMAINS

OF THE

VEGETABLES AND ANIMALS

OF THE

ANTEDILUVIAN WORLD;

GENERALLY TERMED

EXTRANEOUS FOSSILS.

By JAMES PARKINSON.

IN THREE VOLUMES.

STOXK I.ILY.

THE FIRST VOLUME;

CONTAINING

THE VEGETABLE KINGDOM.

LONDON:

PtINTED BY WIIITFINCHAM AND ROWLAND,
Go.titcll Street;

AND PUBLISHED BY SHERWOOD, NEELY, AND JONES, PATERNOSTER-ROW;

J. WHITE, AND J. MURRAY, FLEET-STREET; W. PHILLIPS, GEOKGE-YARD, LOMBARD-STREET; J. ASPERNE,
J. M. RICHARDSON, AND J. AND A. ARCH, CORNHILL; BLACK AND PARRY, LEADENHALL-
STBEET; AND GREENLAND, FINSIIURY-SQUARE.

1811.

T3

EARTH
SCIENCES
LIBRARY

TO

WAKELIN WELCH, ESQ

OF

LYMPSTON, IN DEVONSHIRE,

THIS WORK

IS DEDICATED,

IN TESTIMONY OF THE FRIENDSHIP AND RESPECT OF

JAMES PARKINSON.

GO.-

PREFACE.

IMPELLED by that eager curiosity, which a view of the remains of
a former world must excite in every inquisitive mind, the writer
of the following sheets, long and earnestly, sought for information,
respecting these wonderful substances, from every source to which
he could obtain access. But considerable impediments to his
inquiries arose from his being able to derive so little aid, speaking
comparatively, from such works as have been published in this
country : since although these subjects have engaged the attention
of several gentlemen, well qualified for their investigation ; yet the
publications with which they have favoured the world, have chiefly
been detached essays, on some particular fossils only. He, therefore,
found himself under the necessity of having continual recourse to
the more general observations, which are to be found in the writings
of the learned of Italy, France, and Germany ; the valuable col-
lection of which, in the British Museum, he was happy in being
enabled to consult, with all the advantages which the kindness of
the officers of that noble institution could yield.

Considering that, as similar difficulties must occur to others, a
publication would be acceptable, which should comprise, in the
general history of these bodies, the more important observations.

VI PREFACE.

and opinions of preceding writers, whether foreign or domestic, he
was disposed to take on himself the task of accomplishing, to the
best of his abilities, a work of that description. Numerous difficul-
ties, indeed, offered themselves to his apprehensions ; but these, he
trusted, might yield to an almost enthusiastic fondness for these
pursuits. Many errors and defects, he feared, might obtrude them-
selves on the eyes of the discerning critic ; but these he hoped might,
^
in some measure, be compensated for, by the peculiar information

which would result, from the frequent examination of a tolerably
large and systematic cabinet, obtained from the museums of Mr*
Strange, Lord Donegal, M. Calonne, and of several other collectors.

The kind encouragement of his scientific friends prompted him
to apply himself to the task ; but the doubts and hesitations of
those most in the habits of estimating the success of the offspring
of the press, almost induced him td relinquish his proposed inten->
tion. His arguments in favour of the attempt, derived from the
circumstance of the publications on this subject being so very few,
were powerfully rebutted by the inference, that there were there-
fore but few readers ; and, consequently, but a small demand could
be expected. Partiality, however, to the project he had formed,
and a conviction that ample support might be obtained, were the
attention of the public fairly called to the wonders, which the study
of oryctology discovers, made him resolve on the attempt.

But, aware of the small number of those who, at present, make
this science their study, he feared that a dry, strictly scientific, work

PREFACE. I'll

might not meet with a sale, proportioned to the expense of
undertaking ; he therefore considered it to be necessary to adapt it,
as much as possible, to readers in general. Another consideration
also influenced him to this — he thereby hoped to lead those to
the study of this part of Nature's works, to whom, as yet, they
might be unknown. The epistolary form, from the familiarity of
style which it admits, was therefore adopted ; especially since it
yielded the opportunity of introducing such a portion of intro-
ductory matter, as might secure the comprehending of the discus-
sion by those, to whom it might be, in a great measure, new. In
doing this he was, however, aware that he was trespassing on those
who were already informed on thesfe Subjects ; but, reckoning on
the complacency and liberality with which men of true learning
promote the diffusion of knowledge, he considered their excuse as
already obtained, and no longer viewed this as an objection. -
Gratitude directs, that he should declare how much he is himself
indebted to the prevalence of this generous disposition. With
grateful remembrance of the kindnesses he received from the late Dr.
Gray, Secretary of the Royal Society, he acknowledges his ready
assistance on many occasions, as well as the kind facilities he in-
dulged him with, during his examinations of the numerous valuable
specimens, contained in that department of the British Museum
which he so ably superintended. To Dr. Shaw he is also obliged
for similar attentions. To Charles Hawkins, Esq., William Long,
Esq., George Chandler, Esq., Sir Charles Blick, John Heaviside,
Esq., Sir William Blizard, and Henry Cline, Esq., the Curators of
the Hunterian Museum ; he is under great obligations for like

Till

PREFACE.

indulgencies whilst inspecting that admirable collection. Other
obligations to that friend of science, Sir Joseph Banks, to Dr. James
Edward Smith, President of the Linnaean Society, W.H.Pepys, Esq.,
and other gentlemen, will be acknowledged in the body of the
work.

That the matter of the present volume will be found highty in-
teresting is confidently hoped; but when the vast variety of the
animal kingdom is considered, it is not too much to promise, that,
the subsequent parts of this work will far exceed, in this respect,
the present ; and may therefore yield to the admirers of Nature's ,
works considerable gratification.

CONTENTS.

LETTER I.

RPage
A.TIONVL Application of Wealth and Leisure. ..Snake-stones. ..Fairies changed to Snakes...

Fairies Nightcaps. ..Bones of Giants. ..Thunderbolts I

LETTER II.

Vestiges of the Inhabitants of a former World... Lime-stone and Marble. ..Medals of Creation...
Pleasures afforded by this Science. ..Animals in the former World, different from those of the

present • 6-*

LETTER III.
Early Existence of these Substances. ..Noticed by Xenophanes, Herodotus, Eratosthenes, Strabo,

Pliny, Ovid, &c... .Sketch of the History of the Science , 14-

LETTER TV.

Opinions respecting the Origin of these Bodies. ..Plastic Power. ..Translation of seminal Principles
...Growth of Stones. ..Terms. ..Figured Stones. ..Diluvian Stones. ..Fossils, extraneous or adven-
titious...New Terms proposed... Secondary Fossils, vegetable or animal... Fossilia vulgo dicta...

Impressions... Casts. ..Figured Stones , , 30

LETTER V.

Form of the Earth's Surface. ..Mountains. ..Strata. ..Wisdom manifested in their Disposition. ..Dif-
ferent Kinds of Earths. ..Alumine; forming Clay, Ltthomarga, Slate, &c. .. .Silica ; forming
Rock Crystals, Calcedony, Flint, &c....Lime ; forming Lime-stone, Chaik, Tufa, Marble, &c.
Magnesia; forming Steatites, Asbestos, Serpentine, &c....Sulphurets, Pyrites, or Marcasites.. 3£

LETTER VI.

Pleasures of Travelling.. .Wood-stone. ..Inquiries respecting Vegetable Fossils 47

LETTER VII.
Vegetable Fossils... Fossil Trees... Described by the Ancients. ..By the Moderns... Found in almost

every Part of the World ; 52

LETTER VIII.

Constituents of Vegetables. ..Food of Vegetables 75

LETTER IX.
Resolution of Vegetables into their first Principles... First Step in the Mineralization of Vegetables

...Vegetable Mould. ..Ignis Fatuus 79

LETTER X.
Peat or Turf... Description of.. ..Various Kinds...Length of Time known. ..Found in various Parts

of the World 85

LETTER XL
Bituminous Wood...Surturbrand of Iceland. ..Bovey Coal of England 101

•»' CONTENTS.

LETTER XII.

Pafje

In Answer, from Bovey... Present State of the Coal-pit at Bovey... Strata, &c 123

LETTER XTII.

Bitumens. ..Particular Kinds described. ..Known to Writers of the highest Antiquity. ..History of
Naphtha, Petroleum, and Asphalturn, from the more ancient Naturalists , 127

LETTER XIV.

Account of Bitumens continued, from more modern Authors... Ray, Dolomieu, &c....Tar Lake in
the Island of Trinidad. ..Petroleum Wells in the Burmha Dominions.. .Russia, &c.. 13$

LETTER XV.

Amber. ..Known to the earliest Writers in Natural History... Jet. .. Succinum nigrum of the An-
cients.. .Cannel Coal... Difference between it and Jet......... 150

LETTER XVI.

Coal described. ..Different Kinds of Coal... Doubtful if known to the Greeks, or early Romans...
Brought into common Use, in this Island, but in modern Times... Found in various Parts of the
World ,. 159

LETTER XVII.
Particularities observable in different Coal -pits... Cannel Uoal... Pyrites, &c 175

LETTER XVIII.
Bituminous Fermentation... Com pared with the other Species of Fermentation. ..Bitumens, the

Result of this Process... Peat, a vegetable Fossil, the first Product of this Fermentation 175

LETTER XIX.

Fossil Trees, imbedded in Peat, have undergone the bituminous Fermentation. ..The Changes
which mow-burnt Hay undergoes, somewhat similar to that produced by the bituminous Fer-
mentation . 189

LETTER XX.

Examination of Opinions respecting the Origin of Peat... Aboriginal Formation... A marine De-
posit...Mineral. Origin.. .Floating Islands 195

LETTER XXI.

The purer Bitumens, the Result of the same Fermentation by which Peat has been formed...
Bituminous Fermentation imitates, in its Result, the Operation of Secretion. ..Mineral Tallow,

perhaps of animal Origin. ..Other Arguments in favour of bituminous Fermentation.., 206

LETTER XXII.

Of the Origin of the purer Bitumens. ..Naphtha. ..Petroleum. ..Mineral Tar. ..Mineral Pitch...
Asphaltum. .. Amber. ..Mellite... Jet and Cannel Coal... 218

LETTER XXIII.

Opinions respecting the Formation of Coal. ..Earth impregnated with Petroleum, the Opinion of
Buffon and Gensanne... Opinion of Sig. Arduino...Of Dr. Hutton and Professor PJayfair... Of
Mr. Williams.. .Of Mons. Tingry...Of Dr. Darwin. ..Ofi Mr. Kirwan...Of Mr. Hatchett...Of
Mons. Patrin...Of Mons. Fourcroy 235

CONTENTS. *i

LETTER XXIV.

Page
Inquiry respecting the Origin of Coal continued. ..Hypothesis proposed... Mosaic Account of the

Deluge. ..Objections against. ..Universality of the Deluge. ..Changes thus effected... Vegetable
Matter disposed in Situations in which Coal now exists 246

LETTER XXV.

Inquiry whether the vegetable Matter was deposited at the Deluge under Circumstances favourable
to its Conversion into Coal. ..Bitumen alone not fitted for Fuel. ..Other Matters necessary to be
added. ..Peculiar Arrangement of the Particles 256.

LETTER XXVI.

Recapitulation. ..Apparent Agreement of the Hypothesis with the Economy of Nature 265

LETTER XXVII.

Mineral Charcoal. ..Opinions respecting. ..Subterranean Combustion of Pit-coal. ..Combustion of
Pyrites... Mineral Charcoal 272

LETTER XXVIII.

Pyritous Woods. ..Opinions of Dr. Hutton and Mr. Playfair... Igneous Origin. ..Aqueous Origin
examined 283

LETTER XXIX.

Petrifaction. ..Theories respecting. ..Substitution. ..Adopted by Walch, Kirwan, Daubenton, Four-
croy, &c... .Theory of Dr. Hutton and Mr. Playfair 295

LETTER XXX.

Theory of the Petrifaction of Wood proposed. ..Petrified Wood, silicious, calcareous, and alumi-
nous 300

LETTER XXXI.

Silicious Pebbles. ..Conjectures as to the Time and Mode of their Formation. ..Crystalline Fluid
of Reaumur. ..Agatine Nodules. ..Theory of their Formation. ..Opinions of Dr. Hutton and Mr.
Play fair... Aqueous Origin supported 311

LETTER XXXII.

Silicious Waters of Carlsbad. ..Of Iceland. ..Of Bath. ..Silicious Tufa of the Geyser.. .Vegetable
Calculi. ..Flint in the Epidermis of Plants 323

LETTER XXXIII.

Petrified Wood... Divided into silicious, calcareous, aluminous, &c. ...Silicious divided into sili-
cized Wood and silicized bituminous Wood. ..The latter, into calcedonic, agatine, jasperine,
and opaline 326

LETTER XXXIV.
Calcedonic Wood... agatine... jasperized 331'

LETTER XXXV.
Opaline Wood.. ,The Result of the Union of siHcious and soft bituminous Matter 337

LETTER XXXVI.

Evident Affinity between silicized, bituminous, or opaline Wood and Pitch-stone. ..Analysis of
opaline Wood... Of Pitch-stone.,, Similarity inferred , 34*

CONTENTS.
LETTER XXXVII.

Pasr

-"Semi-opal.. .Experiment on Semi-opal of Telkebanya... Opal. ..Its wonderful Properties. ..Analysis
by Klap roth.. .Horn-stone and Flint •••• ^53

LETTER XXXVIII.

Calcareous Wood. ..Lime frequently held in solution, in 'Water... Various Forms of Deposition...
C&nfetto di 'Tivoli... Quarries of tufaceous Stone. ..Stalactitic Caverns 360

LETTER XXXIX.

Calcareous fossil Wood. ..Where found. ..Calcareous Wood of Oxfordshire. ..Dorsetshire. ..Somer-
setshire...Analysis. ..Mixture of Spar and Bitumen... Calcareous Wood of New South- Wales...
Aluminous Wood, &c. 37+

LETTER XL.

Metallic Fossil Wood. ..Bog Iron Ore. ..Fossil Wood, impregnated with Iron. ..With Copper, &c. 384-

LETTER XLI.

Variety of petrified Woods. ..Proceeding from original natural Difference*.. From the Labours of

Man 391

LETTER XLII.

Varieties of petrfiied Woods continued. ..Those proceeding from the Operationsof Insects. ..Starry
Stone of Chemnitz... Teredo navalis 4/1!

LETTER XLIII.

Secondary vegetable Fossils. ..In Schisti...In Sand-stone. ..In calcareous Strata. ..In argillaceous

Nodules 4u

LETTER XLIV.

Great Difficulty of ascertaining even the Genera of the Plants which are thus preserved... Dorsi-
ferous Plants and Cacti most common > ., 4j@

LETTER XLV.

Fossil Stems of Plants. ..Of the Reed, &c....Fo$jz7mn incognitum , 424,

LETTER XLVI.

Remarks on Leaves contained in Nodules. ..Impressions of the same Side of the Leaf on each No-
dule...Accounted for by Jussieu, Schultz, &c... .Explanation proposed 431

LETTER XLVII.

'Fossil Flovrers... Their Existence doubtful. ..Fossil Seeds and Seed-vessels. ..Fossil Fruits. ..Fossil
Loaves 433

LETTER XL VIII.
Conclusion ...., 45^

ORGANIC REMAINS

OF A

FORMER WORLD,

LETTER I.

RATIONAL APPLICATION OF WEALTH AND LEISURE SNAKE-
STONES FAIRIES CHANGED TO SNAKES FAIRIES* NIGHT-
CAPS BONES OF GIANTS THUNDERBOLTS.

I HAVE long been of opinion, that a considerable portion of
wealth, the fruit of anxious and laborious exertions, would yield,
comparatively, but little enjoyment; unless, during the time de-
voted to its acquirement, care had been taken to fill up some of the
leisure hours, which business could spare, with such amusements, as
would form and cultivate a taste for truly rational pleasures. I am
now convinced, that unless this be done, wealth and leisure, instead
of producing to the man of business the completion of his happi-
ness, will frequently prove to be the source of perpetual torment.
The mind, deprived of its usual entertainment, and not trained
for the adoption of any new mode of exercise, either lapses into the
dreadful torpor of hypochondria; or seeks to obtain a temporary
VOL. i. B

2

gratification from pursuits, unworthy, from their frivolity, or from
their vicious tendencies, to be adopted by a being, endowed with
reason.

I have lived long enough, to have repeatedly witnessed similar
terminations of the dreams of happiness, which have deluded those
men of the world, who, intent only on the acquisition of money,
have supplied their minds with so little information, that they pos-
sessed not the means of using, as a blessing, the hardly earned
wages of a life of care*

Influenced by these observations, and aware of the necessity of
obtaining such resources, I have always allotted a small portion of
my time to-, such : pursuits, as have, at least, excited a disposition
to scientific research,, and an enthusiastic admiration of the beauties
of nature. With my mind thus furnished, I have ventured to avail
myself of the opportunity, which my little fortune affords me; and
have, I trust, quitted the busy part of the world for ever.

In pursuance of a plan, on which I had long determined, of visit-
ing the most interesting parts of this island, I quitted London, last
week, with my daughter, accompanied by our old friend WILTON,
whose lively manners, as you well know, render him an excellent
companion. But he has made himself highly estimable to us on
another account ; his resolute scepticism, with respect to the more
rational, and his submissive credulity, as to the more popular ex-
planations of such natural phenomena, as are beyond the reach of
his understanding, are frequently productive of remarks, so full of
quaintness and of humour, as to render them, in the highest degree,
amusing.

Our first day's journey was not completed, before I discovered, that
the little knowledge, which I had obtained, was insufficient to enable
me to form, even a conjecture, respecting the origin of the very first
object, which particularly attracted our attention. We were within
about ten or twelve miles of Oxford, when WILTON, looking out of

the window of the chaise, exclaimed, " Well, I never saw roads
mended with such materials as these before I" This, of course, drew
my attention to the same object, which had so strongly engaged, his ;
and I am confident, that the astonishment excited in my mind was
but little, if at all, less than that which possessed our friend ; when
I beheld a labouring man breaking to pieces, with a large hammer,
a stone nearly circular, half as large as the fore-wheel of our chaise,
and bearing the exact form of a serpent closely coiled up. Curi-
osity prompted me to stop the chaise, and to ask the man the name
of the stone, and where it came from. "This stone, sir/' says he,
" is a snake-stone, and comes from a pit in yonder field ; where
there are thousands of them." We all alighted, and with surprise
examined some of the same species of stones, which he had not yet
broken, and which, though evidently bearing the form of some
strange animal, were undoubtedly formed entirely of stone.

As we sauntered along, the chaise following us, we came to a neat,
though a small house, on the road side ; which a sign, stuck in the
hedge, on the opposite side of the road, taught us was a house of
public entertainment. Hoping to gain some further information,
respecting that which had so strongly attracted our notice, we entered
this, literally, hedge ale-house. But when introduced into a very
neat room ; the casement of which, surrounded by roses and honey-
suckles in full bloom, opened into a garden, rendered charming by the
wild luxuriancy and profusion, with which its various productions
displayed themselves to our view, we had very little hesitation in de-
termining to stop, and partake of such refreshments, as our cottage
would yield. Whilst these were preparing, WILTON, who was exa-
mining the furniture of the old oaken chimney-piece, said, " Well,
if the object of travelling is to behold novelties, surely this country
will yield that gratification, in the highest degree ; for among the
various things with which this mantle-piece is ornamented, there is
not one, of which I have ever seen its like." They now passed under

4

my examination, but with equal ill success; for neither had I ever be-
held any thing similar; nor could I form any opinion respecting
them.

Whilst we were thus engaged, our landlady made her appearance ;
and from her we learnt, that this was her collection of curiosities,
made in the neighbouring parts of the country. On our requesting
some information respecting them, she very readily proceeded to
communicate to us, all the knowledge of them which she possessed.
Taking up a stone, resembling those which we had seen in the road,
but much smaller^ "This," said she, "is a petrified snake, with
which this part of the country abounds. These were/' continued
she, " fairies, and once the inhabitantsof these parts, who for their
crimes were changed, first into snakes, and then into stones. Here,"
said she, showing us a stone of a conical fnrm7 " is one of the fairy's
night-caps, now also become stone. Do, madam," said she, address-
ing Emma, " pray observe ; is it possible that lace-work, so beau-
tiful as this, should ever be worked by human hands ? This," said
she, " and this, are pieces of the bones of giants ; who came to live
here, when the race of fairies was destroyed." These bones, she
informed us, were frequently dug up in several parts of the coun-
ty ; as well as innumerable thunderbolts : some of which she also
showed us ; stating, that these were the very thunderbolts, with
which these people were, in their turn, also destroyed.

We all listened attentively to our hostess's discourse ; but on my
smiling, when she withdrew, at the romantic account we had re-
ceived, WILTON strenuously defended our good lady's narration ;
and declared, that, in his opinion, it was not without a moderate
share of probability. On our landlady again entering the room, I
did not indeed -venture to offer any doubt of the history she had
delivered ; I only requested to know, whether she knew of any larger
collection of the same kind ? " To be sure," said she ; " our Uni-
Tfersity has aMuseum composed entirely of this- kind of curiosities ;.

and if you be going through Oxford, it will, I dare say, be well
worth your while to take a view of them/'

When we had finished our refreshment, we left our kindly com-
municative hostess ; but not, as you might suppose, with any in-
tention of immediately visiting the Museum of the University. On
the contrary, we were aware, that, without some previous knowledge
of the objects, which are there exhibited, the examination of them
could not yield much satisfaction ; but would serve, merely, to ex-
cite that curiosity, which it was not able to gratify. We have there-
fore settled it, that our visit to the Museum shall be deferred, until
we are enabled to view its interesting contents with that satisfac-
tion, which can only be yielded, when we possess some knowledge
of the objects we contemplate.

Thus, at our very outset, have T experienced a considerable dis-
appointment. The objects I have already seen, and which I have
reason to expect I shall frequently meet with, have convinced me,
that I am totally ignorant of the science, which teaches us their na-
tural history : and also that, without this knowledge, the pleasure
of my journies must be very much diminished. How mortifying will
it be to have objects presented daily to my view, whose forms alone
render them highly interesting, and whose history is most probably
fraught with entertainment ; and to find myself so totally ignorant
of their origin, as not even to know in what class of nature's works
to place them.

You, I know, have long made this branch of natural history your
particular study : and I have been informed, that you possess a col-
lection of valuable specimens of these substances^ which it has ne-
ver occurred to me to request the inspection of. To you, therefore,
I confidently apply ; and earnestly intreat you to supply me with a
regular, and systematic history of these strangely figured substan-
ces, to understand the nature of which, I am impelled by the most
eager desire. The petition I am making will, I trust, be favourably

attended to, when you consider, that, without your assistance, the
pleasure I have promised myself, in my long-proposed tour, will be
considerably diminished : for what, to an inquisitive mind, can be
more mortifying, than to have the curiosity excited to the highest
pitch, without acquiring a single point, on which even conjecture
may be founded ?

LETTER II.

VESTIGES OF THE INHABITANTS OF A FORMER WORLD LIME-
STONE AND MARBLE MEDALS OF CREATION PLEASURES

AFFORDED BY THIS SCIENCE ANIMALS IN THE FORMER

WORLD DIFFERENT FROM THOSE OF THE PRESENT.

1 o comply with the request you have made, will give me real sa-
tisfaction ; since, I am confident, should my endeavours prove
equal to the undertaking, that I shall open to you a source of inex-
haustible pleasure. For, not only the country through which you
are now journeying, but the greater part of this island, and even
of the globe, teems with these curiously-formed stones : the remains
of those beings, which, many ages since, depended, for their exist-
ence, on the various energies of vegetable or animal life. These
bodies, every atom of which they are constituted; existing in a dif-
ferent state of combination from that in which they were originally
disposed, often retain, nearly, the exact figure which they bore
in their primitive state. But the forms which they present to our
view are, frequently, so different from any organized being we have

any knowledge of, that their appearance cannot fail to excite ad-
miration, and an eager desire to obtain all the information respect-
ing them, which can be acquired.

Notwithstanding the interest which they must excite, want of
information, respecting these bodies, generally prevails. Even in
those places in this island, where they most commonly are found,
all inquiries respecting them are, in general, answered only by the
most silly tales and legends. This is, perhaps, attributable to the
circumstance of no particular treatise, on these subjects, having yet
appeared in the English language ; excepting a few valuable papers
in the Philosophical Transactions, Dr. Woodward's Catalogue of
his Collection of Fossils, Mr. Walcot's Description and Figures of
Petrifactions found near Bath, some observations in Mr. Jones's
Physiological Disquisitions, and Mr. Martin's Figures and Descrip-
tions of Petrifactions collected in Derbyshire. What else has
hitherto been published, in this country, respecting them, has
been chiefly in those works which, treating of mineralogy in gene-
ral, have necessarily spoken of these substances, but in a su-
perficial and unsatisfactory manner. In France and Italy, and
more particular in Germany, the most ardent and scientific in-
quiries have indeed been instituted ; in consequence of which,
discoveries of the most curious and interesting nature have been
made. These, however, having been published either in French,
German, or Latin ; and not having yet appeared in an English
dress, it is not to be wondered at that the astonishing information
which they impart, is so little known in this country.

From the consideration of this circumstance, I am disposed to
offer to the public eye whatever information I shall be able to col-
lect, whilst complying with your request ; trusting that the interest,
excited by the subjects of my inquiry, will be sufficient to awaken
attention to a most pleasing, but much neglected science..

The illustrious Bergman elegantly describes fossils, as the MEDA..L&

8

OF CREATION; and, indeed, a very little advancement in the
study of this science is necessary to discover the peculiar propriety
of the application of this term to the subjects of our present in-
quiry.

By these medals of creation we are taught, that innumerable beings
have lived, of which not one of the same kind does any longer ex-
ist— that immense beds, composed of the spoils of these animals,
extending for many miles under ground, are met with in many parts
of the globe — that many enormous chains of mountains are vast
monuments, in which these remains of former ages are entombed —
that, though laying thus crushed together, in a rude and confused
mass, they are suffering those changes, by which they become the
chief constituent parts of the limestone, which forms the humble
cottage of the peasant; or the marble, which adorns the splendid***
palace of the prince.

Surrounded, as we are, by the remains of a former world, it is
truly surprising, that, in general, so little curiosity and attention are
excited by them. Wherever civilized society exists, these wrecks
of the earliest ages may be found, yielding to man the most impor-
tant benefits. Changed in their appearance, during the revolution
of innumerable ages, they sometimes manifest but slight traces of
their former modes of existence : and, having already performed se-
veral important offices in the economy of nature, they are now of-
fered to man, as powerful inducements to the exercise of industry,
and as fit materials, on which his faculties may be exerted. Vary-
ing infinitely in their nature and substance, according to the com-
binations into which they have entered, they become useful to man
in numberless ways.

Not the smallest or rudest village is to be seen, in the neighbour-
hood of a limestone mountain or quarry, but it may be discovered
that these have been ransacked to furnish the foot-path, or to aid
the erection of the poor man's dwelling. In visiting the mansions

of the rich, we shall in general find, that, in proportion to the
wealth and consequence of the possessor, will the more solid parts
of the building be composed of these remains of animated beings,
which lived in a former world. For the external part of such build-
ings, the architect finds no substance so well adapted, from its du-
rability, and its easy yielding to the instrument, as the various kinds
of coarser limestones ; nor for the more fine, internal and ornamental
work, any substance so well calculated, by its fineness of texture.,
and pleasing appearance, to unite the advantages of strength and
beauty, as the various marbles.

Although insuperable difficulties may oppose that theory, which
attributes the formation of all these substances, to the decomposi-
tion of certain kinds of animal matter ; yet I have no hesitation in
asserting that a very considerable portion of those masses, entirely
owe their origin to that process. Seldom is a block of limestone
severed, but the cut surfaces show the vestiges of animals, and of
their domiciles : and frequently, the polished slab of marble will
be found to be almost wholly composed of similar remains. Thus
we perceive that matter is in constant motion ; being impelled, in
regular progression, through various forms, and modes of existence:
being thus made to perform those important functions, on which the
life, as it were, of this globe depends.

The study of animated nature affords more amusement, and ex-
cites more general attention, than, perhaps, any other department of
natural history. It yields to the mind the amplest gratification, by
the positive and indubitable information it conveys, respecting the
varying economy, and the curious instinctive habitudes, which dis-
tinguish the numerous species of animals ; and by displaying the al-
most insensible shades of difference, by which the varieties of each
species are distinguished ; and the more marked and striking con-
trast, by which each species is separated from the other. Nor yet is
the mind feasted to fulness ; since, at the same time, the several pro-

V.OL, i. c

10

cesses, serving to support animal life and the infinitely varied modes
of organization, which exist even in the same being, cannot fail to
excite an eager desire, to obtain still further knowledge, respecting
those astonishing operations, in which, although the effects are so
'obvious and even palpable, the immediate causes demand the closest
investigation for their discovery. In consequence of this, although
the mind obtains a considerable fund of pleasing and positive in-
struction, it is so far from experiencing the torpor of satiety ; that it
looks forward, with increased ardour, to the extention of its acqui-
sitions.

The science, into the study of which I propose to lead you, also
possesses these advantages, in a very eminent degree. You will be
taught, clearly, by it, that the formative and preservative powers, ap-
pointed by the Almighty, are momentarily exerted on the smallest
particles of matter : that nature, by which I mean the personification
of these powers, is constantly employed also on the largest, and ap-
parently most inert masses of matter, in accomplishing the several
processes, necessary for the support and continuance of the earth, and
its inhabitants. You will behold her, incessantly labouring in the
deep recesses of the earth ; as in the laboratory of the universe, re-
ducing to form and beauty, the mutilated wrecks of former ages.

Nor can the mind be much more pleasingly exercised, in the re-
gions of conjecture, than by the curious inquires to which the con-
templations of objects, so interesting, must necessarily lead. Many
of the curiously figured stones, which will offer themselves to your
observation, you will be pleased in finding, on a close observation,
were once, as I have already remarked, beings endowed with the
powers and faculties of vegetable or animal life. You will, by care-
ful comparison, discover, that, of these, several species, are still to
be found, in a living state ; but, most commonly, in parts of the
world very remote from those, in which their remains are thus won-
derfully preserved. Other animals you will find thus astonishingly

11

entombed, possessing, indeed, many of the anatomical character-
istics of animals now existing; but differing so much, in other re-
spects, as to require to be considered, as entirely different from any
which are known now to exist. Thus you will behold the bones of
an animal, of which the magnitude is so great, as to warrant the
conviction, that the bulk of this dreadful, unknown animal, ex-
ceeded three times that of the lion ; and to authorize the belief, that
animals have existed, which have possessed, with all the dreadful
propensities of that animal, its power of destroying, in a three-fold
degree. You will also view the remains of a being of the magni-
tude, at least, of the elephant ; which was armed with tusks, equally
dreadful, as a weapon, with those borne by that animal; and pos-
sessing, in addition to these, enormously huge grinders, supposed,,
to bear the distinctive marks of those creatures, which gain their
food, by preying on those of inferior powers and size. The jaws of
an animal bearing a near resemblance to those of a crocodile, you
will perceive to be armed with teeth, not widely different from those
of the shark. In a word, you will be repeatedly .astonished by the
discovery of the remains of animals, of which no living prototype
is yet found.

When the mind has dwelt awhile on objects so well calculated to,
impress it with astonishment, fresh subjects for conjecture, and most
interesting contemplation, will arise. The number of these wrecks,
of a former world must, as well as the situations in which they are
found, excite the highest admiration. — Not in one particular spot —
not in one region — not in one quarter of the globe alone — but where-
ever this world has been explored. In the greatest subterraneous,
depths, in the bowels of mountains, and on heights vastly above
the level of the sea, are these wonderful remains to be found. But

enough 1 have pressed so far on, as to be under the necessity

of craving your indulgence, for credit, for the proofs of what 1 have
already stated,, which I promise satisfactorily to produce.-*-In

meantime, surely I may presume that you begin to perceive, that
this part of natural history possesses importance sufficient, to claim
a very considerable degree of attention. To confirm you in this
opinion, I must add, that by these studies a more perfect knowledge
is gained of the structure of this globe, of its ancient state, and, of
the various and important changes it has suffered.

By widening the views of the natural philosopher ; by opening to
him, fresh fields of observation ; and, by showing him a glimpse of
other creations ; more just, and more grand sentiments, also must
be excited, of the immensity of animated nature, and of the power
of the great Creator of all things.

In pursuing these investigations, I shall, in general, adopt the
following order. The fossil, in its present state, will be carefully
described ; and, whenever it can be done, the situation in which it
is found will be pointed out ; its original mode of existence, and
the various properties which, by analogy, may be supposed to have
characterised it in its living state, will be inquired into ; and the se-
veral changes which it has undergone, both in its composition and
its structure, will be carefully examined.

The wonderful changes of situation, which the various objects of
investigation will be found to have undergone, will necessarily
demand an assiduous inquiry. The endeavour to furnish some sa-
tisfaction on this abstruse and interesting subject, will be reserved,
as much as may be, for the concluding part of our inquiries. This
place it will occupy, with the most propriety ; since the several facts
and observations, detailed in the preceding part, will furnish some
of the data, which may serve as the foundation for the reasonings,
and conjectures to be advanced there. It is proper, however, in this
place, to remark, that, on this subject, but little positive knowledge
can be acquired ; and that even after the most assiduous inquiry,
the mind must be satisfied with forming probable conjectures. In-
deed, the attempt to account for the astonishing appearances,

13

which the surface of this globe presents, appear to many, as indi-
cating a very improper degree of confidence and presumption.

To trace the operations of nature, in periods far behind all human
record ; to pronounce opinions respecting the structure and the in-
habitants of a former world ; and to endeavour to find out the ways
of God in forming, destroying, and reforming the earth ; do cer-
tainly appear to be tasks, to which the limited powers of man are
but little adapted. But since the world we inhabit is evidently
composed of the wrecks of a former world ; the materials of which
that world was composed are, of course, at hand for our examina-
tion. The remains too of its former inhabitants are frequently
found preserved, in such situations as teach us. something, not only
respecting the extent of the changes, which have taken place on the
surface of this globe ; but even the particular element which was
employed, as the chief instrument of destruction, and of renova-
tion. Scripture, likewise, corroborated by the collateral evidence
of all human tradition, supplies us with the grand leading facts ;
that after the complete formation and the peopling of this globe, it
was subjected to the destructive action of an immense deluge of
water ; all the fountains of the great deep were broken up ; the
high hills that were under the whole heaven were covered ; and
every living substance was destroyed, which was on the face of the
earth. Chemistry and mineralogy also furnish us with their aid, by
which we are taught the several changes, of which these substances,
under various circumstances, are susceptible.

By these aids, we may sometimes be enabled to form, perhaps, a
tolerably correct judgment, respecting some of the grand changes
which took place, during the vast revolution which this planet has
experienced. But so very remote is the period, to which our minds
are to revert : so loose, and so light, are the grounds on which our
conjectures are to be built : and so great is the temptation to ima-
gination, to take the place of judgment, that, among the several

14

systems, of which I shall have occasion to make mention, you, not
only, will hardly find one on which you can venture to depend ; but
you will discover, that the majority, so far from possessing even
probability, rather resemble the fictions of poets, than the reason-
ings of philosophers.

Yours.

LETTER III.

EARLY EXISTENCE OF THESE SUBSTANCES NOTICED BY XENO-

PHANES, HERODOTUS, ERATOSTHENES, STRABO, PLINY, OVID,
&C SKETCH OF THE HISTORY OF THE SCIENCE.

A SLIGHT review of the history of what has been hitherto accom-
plished, in the endeavour to promote, and diffuse the knowledge
of these subjects, cannot, in itself, but be highly interesting. At
the same time, it will show the necessity of such a work, as is here
attempted ; in which a summary account is intended to be given
of the several discoveries and opinions, which have, at different pe-
riods, been published ; since, by thus placing them by each other,
in a fair point of view, a proper judgment may be framed of their
respective merits, and useful truths may be the result of the com-
parisons thus made.

In the earliest philosophical writings, which have been transmit-*
ted to us, numerous proofs are to be found, that the existence of

15

substances, which had undergone the process of petrifaction, had
not, in those ages, escaped observation.

Xenophanes,the founder of the Eleatic sect, who wrote upwards
of 500 years before Christ, maintained that God and the world were
the same ; and contended for the eternity of the universe. In sup-
port of the latter opinion, he dwelt much upon the circumstance of
petrified shells being found, in the internal parts of mountains, and,
in the bowels of the earth. He related, that, in the quarries of Sy-
racuse, the impressions of fishes existed ; that the impression of a
small fish was found, deeply imbedded in a rock at Paros ; and, that
almost every species of marine animals had been thus preserved ;
he inferring, from the appearance of these extraordinary pheno-
mena, that these places must, in very distant ages, have been co-
vered with the sea*.

Herodotus, who wrote 440 years before Christ, speaks particu-
larly of shells existing in the mountains of Egypt ; and concludes,
from this circumstance, and the saltish emanations which injured
the pyramids, that the sea had gradually retired from these partsf.

Theophrastus was supposed to have written a book, entirely on
petrifactions, and which though ranked amongst his lost works, was
imagined to have been in the possession of Pliny; and to have
yielded him some portion of assistance, in that part of his Natural
History.

Eratosthenes, who lived 200 years before Christ, when inquiring
into the figure ofthe earth, also considered it as a question worthy
of investigation — How it could have happened, that vast numbers
of oyster, and other shells, should be found scattered in many
places at a very considerable distance from the sea. This phenome-
non had also been noticed by Strato, and by Xanthus of Lydia, as
well as by Strabo himself; who refers to and corroborates their re-
marks in the first book of his Geography ; particularising some of

* la Originis Philosophumenis, cap. xiv. p. 100. t Lib. ii. sect. xii.

16

the species of shells thus changed, and the places where they were
found.

That substances, which had undergone this extraordinary change,
existed upwards of two thousand years since, in quantities so con-
siderable as to have excited the attention of the Grecian philoso-
phers, is therefore very evident. So prodigious and so extensive
were the effects they noticed, that we find almost all of them con-
tending for the eternal duration of the world ; finding it difficult to
conceive any period of time, in which changes, so vast and extraor-
dinary, could be accomplished.

The Romans, more disposed to cultivate the fine arts, and to en-
courage works of genius and imagination, did not pursue the study
of natural history with much avidity. Excepting in the works of
Pliny, but little of originality is discovered in the writings of their
natural historians. They appear to have contented themselves with
merely preserving the discoveries of the Greeks ; neither seeking to
add to the stock of facts, which had been already collected ; nor, by
their researches to ascertain, what degree of reliance might be placed,
on the various histories of nature which had been transmitted them.

In the works of Pliny who wrote near 1800 years ago ; and in
that part of his writings, which probably are considerably indebted
to the lost work of Theophrastus, who wrote about 300 years before
Christ, we find mention is made of several substances, which future
observation has taught must have undergone the process of petri-
faction. Among the most remarkable of those of which he speaks,
is the Bucardia, like to an ox's heart — Brontia, resembling the head
of a tortoise, supposed to fall in thunder-storms — Glossopetra, like
to a human tongue ; which does not grow in the earth, but falls
from heaven whilst the moon is in its wane — Hammites, like the
spawn of fishes — The Horn of Ammon possessing, with a golden co-
lour, the figure of a ram's horn — Lepidotes, which imitates, in va-
rious colours, the scales of fishes — Meconites, resembling the poppy —

Ceraunia and Ombria, supposed to be thunderbolts — Ostracites,
which, though harder than shell, bears the name and resemblance of
the oyster — Syringites, which is formed with cavities, by which it
resembles the pipes of straw — Spongites, bearing the form of sponge
— Phycites, resembling sea-weed or rushes.

He also speaks of a black light substance, resembling wood ;
of stones, resembling the teeth of the hippopotamus ; and observes,
that Theophrastus speaks of fossil ivory, both black and white ; of
bones born in the earth ; and of stones bearing the figure of bones.
Ovid tells us,

Vidi ego, quod fuerat quondam solidissima teMus,
Esse fretuin. Vidi factas ex aequore terras :
Et procul a pelago conchae jacuere marinae ;
Et vetus inventa est in montibus anchora summis.

Metamorph. lib. xv. /. 262.

Alexander ab Alexandra says, he remembers to have seen in the
mountains of Calabria, at a considerable distance from the sea, a
variegated stone of a hard marble, in which many sea-shells, but lit-
tle changed, were heaped, forming but one mass with the marble.
He also relates, that Jovianus Pontanus informed him, that being
once on the promontory of Pacusilypus, near Naples, he saw in the
middle of a piece of a stone, which was broken from the rock by
the violence of the tempest, a wooden beam, surrounded on every
side by stone, and grown into one body with the rock*.

• Tertullian also, anxiously endeavouring to prove, from natural
appearances, that a general deluge had, according to scripture,
taken place ; dwells, particularly, on the discovery of the remains of
marine animals on mountains, and on various parts of dry land, at a
considerable distance from the seaf.

For several succeeding ages, the writers of natural history were, at

* Genialum Dierum, liber quintus, 1532. f De Pallio, cap. ii. pag. 6. ed. Salmas.
VOL I. I>

18

least, with respect to their account of these substances, little more
than mere copyists of Pliny ; who, although he had affixed names to
these substances, descriptive of the forms they possessed, meant not
thereby to give any opinion as to their origin.

In the thirteenth century, Albert le Grand* speaks of the branch
of a tree being found, on which was a bird's nest; with birds
contained in it, the whole being a mass of stone. The visformatwa
of Aristotle was, however, sufficient to account, in the opinion of
Albert, for this extraordinary phenomenon. But the opinions, which
were entertained at this period, respecting these substances, were
exceedingly incorrect. The doctrine of equivocal generation, which
had been adopted by the disciples of Aristotle, contributed very
much to mislead those who made these substances the subject of
their inquiries ; since, by also adopting the aid of certain occult
qualities, their origin was supposed to be thus satisfactorily ac-
counted for. Certain plastic powers were supposed to employ their
influence in the earth, in creating substances, which bore the figure
and resemblance of various vegetable and animal substances. To
account for their formation, therefore, it was thought sufficient to
refer to the hidden powers of the vis plastica, the vis formativa, and
the vis lapidificativa.

In the sixteenth century, about the year 1517, the workmen em-
ployed in rebuilding the citadel of St. Felix, at Verona, discovered,
that the rock, on which it was built, was full of petrified shells.
This discovery excited the attention of the learned, to a very consi-
derable degree ; some attributing them to the active influence of
the vis formativa ; whilst others perceiving their exact resemblance
to real shells, declared, that they must be actual marine bodies thus
enveloped in stone, by some accident. We learn, that when Fra-
castorius was asked his opinion respecting this phenomenon, he

* Mineral, tract. I. lib. i.

19

made for answer, that it had been attempted to be accounted for
in three different ways. Some attributed it to the vis plastica and
formativa of Aristotle : others supposed these substances to have
been real marine bodies, deposited in these places at the time of a
general deluge : whilst others had adopted that opinion, to which
he himself was most inclined ; that the parts, where these marine
bodies were found, had formerly been covered with the sea, which
gaining insensibly, in some parts, on the dry land, gradually changed
its bed, leaving the positions it had formerly occupied for the cul-
tivation and possession of man*.

In the sixteenth century, Agricola, to whose indefatigable spirit
of inquiry, mineralogy is very much indebted, spoke much more
explicitly of extraneous fossils than had hitherto been done* He
particularly mentions the entrochi, and relates several instances of
trees, and parts of trees, being found in a petrified state, at consi-
derable depths in the earthf . But it is evident, that Agricola was
not partial to inquiries respecting extraneous fossils ; his attention
was chiefly engaged in mineralogy, to the promotion of which his
industry added very considerably.

In 1565, Conrad Gesner published, at Zurich, a work of great me-
rit, De Rcrum Fossilium, Lapidum, et Gemmarum, Figuris. About
this time John Kentman, a German, collected a cabinet of petri-
factions, which, considering the period in which it was formed, ap-
pears to have been very respectable. The catalogue of it is con-
tained in Gesner's work. About the same time Valerius Cordus, a
celebrated physician, undertook to publish a general oryctography
of Germany ; but does not appear to have received such encourage-
ment, as would have warranted the prosecution of his plan.

* Bonani Musaeum Kircherianum, p. 198. Musaeum Calceolarii et Musaeum Com
Moscardi, p. 172.
t De Ortu et Causis Subterr. lib. iii. et De Natura Fossil, lib. vii.

20

Toward the close of this century, Bauhin formed a copious col-
lection, and published the necessary descriptions of the petrified
shells, which were found near the baths of Boll. This descriptive
catalogue is to be found in his Historia novi et admirabilis Fontis
Balneique Bollensis, in Ducatu Wirtembergico. Montbeillard, 1598.

About the same time Michael Mercatus wrote his Metallotheca
Vaticana, which was not, however, published until the year 1717?
when it was given to the public by Lancisius, physician to the pope.
The opinions of Mercatus not differing from those which prevailed
in the age in which he wrote, are not indeed very interesting ; but
the notes of Lancisius, and the figures, which are executed in a very
masterly manner, and which convey very accurate ideas of the
bodies they represent, render the work of value.

In the seventeenth century, collections of fossils became much
more general. Only two catalogues of collections had hitherto ap-
peared, but now several very extensive ones were published. In
1622, appeared a copious description of the celebrated museum of
Calceolarius, of Verona; and twenty years after that was published
the catalogue of Besler's collection. In 1652 appeared Wormius's
catalogue ; in 1663 was published Spener's, and in 1666 Septala's.
An account of the museum of the king of Denmark was published
in 1669; in 1674 Cottorp's catalogue appeared; and in 1678 was
published that of the celebrated Kircher. In 1687 Dr. Grew wrote
an account of the curiosities, which were contained in the museum
of Gresham- College ; and, in the year 1695, appeared the catalogue
of Petiver, an apothecary, in London, who, at a vast expense, had
formed a most valuable collection.

The earliest writer on these subjects, in this century, was Caspar
Schwenkfeld, who, in 1600, published a catalogue of the fossils dis-
covered in Silesia. But the most intelligent writer, of this period,
was Fabius Columna, who published, in l6l6, his treatise De Glos-
iS) a work of considerable merit, intended to correct the erro-

21

neous opinions which had been entertained respecting these parti-
cular substances. In this century also, John Johnston, in the No-
titia Regni Mineralis, Lipsice, 1661, described several petrified shells:
he also particularly treated of the Cornu Ammonis, but evidently
without supposing it to have been a shell. Numerous accounts
were given respecting the astonishing properties which some of
these figured stones possessed : and so fabulous and absurd were the
greater part of them, that nothing but the darkness of the age could
excuse the positive manner, in which they are related, and the firm
belief which some appeared to have placed in them. One of these
I will venture to introduce, leaving you to judge from that of the
rest. It is related in Historia Nature? Joannis Eusebii Nierembergii.
Antverpice, 1635. pag. 430, cap. De Lapide in Insuld Mond.

" There is here a stone almost shaped like a human thigh, which
possesses this wonderful property, that being carried away to any
distance, it returns, of itself, the next night ; as has been fre-
quently found, by those who reside here. Hence it happened
that Count Hugh, having heard of the power of which this stone
possessed, had it secured, by strong i/on chains, to another stone,
which was much larger than it, and cast at a considerable distance
into the sea : but when morning dawned, to the wonder of the
multitude, the stone was again found in its former situation. On
this account, therefore, it was prohibited, by a public edict of the
Count's, that any. one should again attempt its removal. But, it
happened, on a time, our author informs us, that a certain country-
man, for the sake of making a fair experiment, bound the stone to
his thigh — directly the thigh became mortified, and the stone

escaped, and returned to its former situation/' But to return to

our sketch. To enumerate all the writers on orycto ogy of this
period would be unnecessary ; it will be sufficient to mention some
of those authors, whose works deserve most particular attention.

22

Nic. Steno, in a dissertation, De Solido.intra Solidum Contento, pub-
lished in 1639, at Florence, displayed a considerable degree of sound
judgment in his inquiries respecting these substances. The Museum
Metallicum of the indefatigable and illustrious Aldrovandus, publish-
ed in 1648, also contains the descriptions and delineation of several
fossil bodies. The work of Augustino Scilla, De Corporibus marinis la-
pidescentibus, published at Naples in 1670, also supplies a consider-
able portion of information, the result of most careful and anxious
inquiry. About this period too, several learned men undertook to
publish the oryctological history of several different parts of Germany,
Italy, &c. Thus the fossils of Silesia were described by Caspar
Schwenkfeld; those of Hildesheim by Frid. Lachmund, in 1669; and
those of Switzerland, in 1680, by Jo. J. Wagner. About this time
was also published a dissertation, by Jo. Dan. Geyer, at Frankfort,
De Montibus conchiferis et glossopetris Alzeyensibus ; and at Leipsic, a
dissertation by Albertus, De Figuris variarum Rerum in Lapidibus, et
speciatim Fossilibus, Comitatus Mansfeldice. Nor were the fossils of
this country neglected ; the Lithophylacii Britannici Ichnographia
of Lhwyd, published at Oxford in 1669, contained a very ample ca-
talogue of English fossils, contained in the Ashmolean Museum. In
1664 was published, by Thomas Lawrence, Mercurialis Centralis ; or
an Account of Subterraneal Cockle and other Shells in Norfolk.
Several English fossils are also described in Dr. Plott's Natural
History of Oxfordshire, published in 1686 ; as well as in that of
Staffordshire, written by the same author. In the Natural History
of Northamptonshire, by Dr. Morton, and in Dr. Leigh's Natural
History of Cheshire, Lancashire, and of the Peak of Derbyshire,
which were published nearly at this time, several curious particulars
are recorded, relative to fossil bodies found in these parts. But the
most important publications of this period, which related to these
substances, were those of Dr. Woodward, particularly, the Natural

23

History of English Fossils. This valuable work contains a cata-
logue of that valuable collection of fossils which the Doctor had
formed, and which is now in the possession of the University of
Cambridge. Some notice is also taken of these substances in Chris-
topher Merret's Pinax Rerum naturalium Britannicorum, the first
part of which was published in 1667 ; at the same time Mons.
Childrey published, at Paris, L'Histoire des Singularites naturelles
d'Angleterre, d' Europe, et du Pays de Galles, in which several fossil
substances are spoken of.

Rieske, Major, Kirchmajer, and Sachs, deserve also to be mention-
ed, for the aid they yielded to this science at this period. Several very
valuable contributions also appeared, in different periodical publica-
tions, illustrating several parts of the science. Among those most
worthy of attention, a dissertation of Wolfgang Wedel may be
placed, with the utmost propriety. In this dissertation, De Conchi*
saxatilibus, which he introduced in 1672, in the Ephernerides pub-
lished under his direction, he differed widely from his contempora-
ries ; and unreservedly asserted, that the stones, bearing the form of
shells, were actual petrifactions, being natural shells converted into
stone.

Among the last supporters of the opinion of the generation of
these bodies in the bowels of the earth, may be mentioned the cele-
brated Langius, who strenuously contended for their having thus
obtained their forms and existence : Dr. Plot, who believed their
figures to result from the operation of certain plastic powers with
which certain saline bodies were endowed : and, lastly, Lhwyd,
who combated the vis plastica of Plott, and supported the ideas of
their production from the seminia of fishes, &c. raised with vapours
from the sea ; and conveyed by the clouds and rain, through the cre-
vices into the internal parts of the earth. The more rational con-
jecture of Woodward, who attributed their situation to the effects
of the general deluge, was rendered of less effect, in opposing these

24

notions, from his having attributed to the waters of the deluge, an
almost universal solvent power ; by which he supposed the rocks and
mountains were melted down, and thus allowed the admission of
these substances into their external parts : not considering that, by
the same power, these bodies would themselves have been reduced
to a mass, not bearing their proper figures.

Nothing, perhaps, contributed so much towards diffusing a proper
idea respecting the origin of these substances, as the Historia Anima-
lium Anglice which contained some excellent remarks, De lapidibus
ejusdem Insulce ad Cochlearum quandam Imaginemjiguratis. Lond. 1678 ;
and the Historia sen Synopsis methodica Conchy liorum, 1685, all writ-
ten by Dr. Lister. By these publications the student was enabled to
form a comparison, between the original shell, and the similar shell
in a fossil state ; since, in several instances, the Doctor had display-
ed in his plates, the same shell in both states. How much this must
have contributed to producing a just judgment, of the real nature
and origin of these substances, must be obvious ; and to this circum-
stance, perhaps, we ought in part to attribute the change of opi-
nion, which very generally took place at this period. Still, however,
the science was involved in that cloud, which had so long obscured
it. The vis plastica, the vis formativa, and the sportive creations of
nature, werfe terms yet in frequent use. Those that were more than
half convinced, but had not quite shaken off the influence of a long
adopted opinion ; as well as those who, though quite convinced, had
not the courage to acknowledge having been in error ; spoke of these
bodies in the indefinite language of lapi des figurati, lapides idiomor-
phi, lapides qui jiguram habent concha, cochlece, $c. Some indeed
would venture to term them conchce lapidece, ostrece lapidece, $c. care-
fully avoiding to speak of their origin, or to admit them to be
bodies, changed from their original animal state to that of stone.

Careful investigation, however, having rendered it manifest,
that these substances were neither the productions of chance, nor

25

the creatures of these imaginary capricious powers, they excited
more general attention: and being better understood, they became
more capable of systematic arrangements, and the study of them
embraced more of science.

The eighteenth century, therefore, commenced under the most
favourable circumstances for this science. The learned and indus-
trious Scheuchzer, who had adopted the most rational theory respect-
ing the origin of these substances, published, in 1702, his Lithogra-
phia Helvetica Curiosa ; which was followed by his Piscium Querelce
et Vindica, in 1708 ; with his Herbarium Diluvianum, in 1713; and his
Musceum Diluvianurn, in 1716, Mylius, Bajerand others also, about
this time, published the oryctological discoveries which had been
made in the several parts in which they resided, or which they had
explored. Among these writers, none deserves more particular men-
tion, than the accurate and diligent Rosinus ; whose examination of
the encrinus may be regarded as a model by which all similar in-
quiries should be directed. His projected works promised very con-
siderable addition to the knowledge of fossils ; but these were sup-
pressed by his premature death. Bruckman also pursued this kind
of inquiry, with the utmost assiduity and success ; which is rendered
evident by his work, de Lapide Nummali Transylvania; as well
as, by the numerous observations, in his epistolary accounts of
what he had discovered worthy of notice in his various travels.
The works of Ritter, •. which were published also about this
time, contain much oryctological information. Indeed the science,
now rendered respectable, by being divested of the numerous absur-
dities, with which ignorance and false philosophy had loaded it,
was assiduously cultivated by many learned and ingenious men ; and
became more and more interesting, from the numerous objects of
astonishment it displayed. Linck, Jacobus a Melle, Harenberg,
L Ehrhart, Volckman, Klein, Donati, Reaumur, with many other
VOL. i. E

26

men of learning, aided the progress of the science by their well
directed labours.

One work published in 1726, deserves to be particularly noticed ;
since it plainly demonstrates, that learning may not be sufficient to
prevent an unsuspecting man, from becoming the dupe of excessive
credulity. It is worthy of being mentioned, on another account :
the quantity of censure and ridicule, to which its author was ex-
posed, served, not only to render his cotemporaries less liable to
imposition ; but also more cautious in indulging in unsupported
hypotheses. The work is intitled Lithographic Wirceburgensis Speci-
men Primum, and was"written by Dr. John Bartholomew Adam Be-
ringer. We are here presented with the representation of stones,
said to bear petrifactions of birds ; some with spread, others with
closed wings : bees and wasps, both resting in their curiously eon-*
structed cells, and in the act of sipping honey from expanded
flowers: spiders weaving their webs: moths and butterflies engender-
ing: and, to complete the absurdity, petrifactions representing the
sun, moon, stars, and comets, with many others too monstrous and
ridiculous to deserve even mention. These stones, artfully prepared,
had been deposited, purposely to dupe the enthuiasstic collector,
in a mountain, which he was in the habit of exploring. Unfortu-
nately, the silly and cruel trick succeeded so far, as to occasion to
him, who was the subject of it, so great a degree of mortification,
as, it is said, shortened his days.

In the middle of the eighteenth century a more strict and close
mode of philosophising, than had been hitherto employed, appears
to have been generally adopted : this is evident in almost all the
writings which were published on these subjects at this period.
Correctness of judgment, and propriety in arrangement, became
now generally conspicuous. This we can without the least hesita-
tion, attribute, in a great measure, to the advantages which, this

27

science derived, with mineralogy, from the well directed labours of
those, who strove to place the different productions of nature under
appropriate classes. On this account, muqri is undoubtedly due to
the scientific exertions of Linnaeus and of Wallerius : both of these
writers, in their different systems of arrangement, having taken a
very comprehensive view of the objects of our enquiry. The oryc-
tology of D'Argenville is replete with information, which must be
highly acceptable to the admirer of lithology. Gesner's (Jo.) dis-
sertation De Petrificatis, published in 1758, is highly valuable, as a
faithful and neat compendium of the science. The Trait 6 des Petri-
factions of Bourguet is a work which is also more useful ; from its
yielding the illustration of faithful plates, and the advantage of
a convenient arrangement. But the work, which comprises the
most information, and indeed, from which every lover of the sci-
ence must derive the greatest degree of satisfaction and pleasure,
is that of the celebrated Mr. Knorr, published in Germany, en-
titled, Recueil des Monumens des catastrophes qui la Globe de la
Terre a essuiees. This magnificent work, contained in three folio
volumes, and adorned with elegant coloured representations of
different specimens, was began by the learned G. W. Knorr, and
at his death was continued with equal care and zeai by Mr.
Walch.

The only works, entirely devoted to these subjects, which have
appeared in England since the republication of Lhwyd's work, are,
Descriptions and Plates of Petrifactions found near Bath, by John
Walcott ; and Gustavus Brander's Fossilia Hautoniensia, in Musceo
Britannico deposita ; the scientific descriptions of which were written
by Dr. Solander. Through the whole series of the Philosophical
Transactions of the Royal Society of London, is dispersed, a consider*
able portion of information respecting the remains of the ancient
world, in communications from Sir Hans Sloane, the Hon. Daines
Barrington, Dr. Stukely, Dr. Molyneux, Dr. Mortimer,Dr. C

28

per, Dr. Hunter, Mr. Ray, Mr. Joshua Platt, Mr. Da Costa, Mi-
John Hunter, and many other gentlemen distinguished for their
avidity of research, and their extensive knowledge respecting
the astonishing productions of nature. The Academics Scientiarum
Imperialis Petropolitance Comment arii, contain some very excellent
papers on these subjects, by Professor Pallas. The Societatis Region
Scientiarum Gottingensis Commentarii, the Memoires de I' Academic
Koyale des Sciences, also contain several very instructive papers. In
the Transactions of the American Philosophical Society, some in-
teresting papers have lately appeared, by Thomas Jefferson, Esq.
Dr. Wistar, and Mr. Turner, respecting the bones of various un-
known animals, which have been discovered in that part of the
world.

In 1781 were published, some very interesting observations on
these subjects, in the Physiological Disquisitions of Mr. William
Jones.

In 1793 was published, by Mr. Martin, of Buxton, a work, con-
taining figures and descriptions of Petrifactions collected in Derby-
shire. Of this work only seven numbers have been yet published.
The figures are given with such fidelity, and the descriptions with
so much accuracy, that it is only by supposing the natural history of
these substances is not so generally known, as to have excited a suffi-
cient degree of interest in collectors, that we can account for the pub-
lic demand not having called for their more frequent publication.

Cuvier, in a paper given into La Societ6 d'Histoire Naturelle, at
Paris, has published some important remarks on the fossil remains
of various unknown animals ; and has likewise announced his inten-
tion of publishing his inquiries on this subject, on a very extended
scale. From this work so much information is to be expected, that,
I doubt not, its publication will prove an important epoch in the
history of this science.

It must, however, be acknowledged, that during the last fifty years,

29

but little has been done in this part of the world, towards the ad-
vancement of this science. Many gentlemen, indeed, have formed
large and valuable collections, and must have made many impor-
tant and valuable observations, but, unfortunately, very few of these
have met the public eye. Indeed the study has been, in this coun-
try, confined to so small a number of persons, that prudential rea-
sons must have had considerable influence, in deterring the inge-
nious observer from risking the expenses of publication.

This culpable neglect of a study fraught with interest, instruc-
tion, and amusement, is certainly attributable to our not possessing,
in the English language, any work which furnishes a regular and
connected account of the numerous petrified bodies, which almost
every where surround us. For want of this kind of information,
these truly astonishing substances, excite, in general, only a mo-
mentary wonder ; instead of leading the mind to compare them with
the living beings they resemble, and to mark, from the endless va-
rying forms, observable, even in their spoils, the number of beings
which once existed, but whose living archetypes are now totally
unknown ; and are entirely unnoticed in the earliest descriptions of
the works of nature.

Surely it is not too much to hope, that a faithful history of these
substances ; tracing them, where it is possible, to their analogous
living beings ; and where not, to such as they most resemble ; point-
ing out, according to rational conjecture, the modes in which they
probably existed, and the stations which they have been appointed
to fill ; and tracing the influence which the changes, suffered by
this part of animal creation, has had on the globe we inhabit ; may
excite the admirers of nature again to turn their attention to these,
not her least beautiful, nor her least admirable works.

The present period is surely auspicious to this hope. Mineralogy
has already obtained a firm and wide footing ; and the study of ani-
mated nature must be daily gaining admirers, from the pleasing

30

illustrations of Mr. Sowerby, Mr. Donovan, the scientific pub-
lications of Dr. Shaw and the ingenious lectures on Comparative
Anatomy by Mr. Macartney ; not to particularise the numerous
interesting observations of Mr. Home, Mr. Corse, and various other
ardent admirers of natural history. The science then, the study of
which is here intended to be promoted, and which not only deserves
to be considered as supplementary to zoology and mineralogy ; but
as the medium by which the one may be connected with the other,
cannot surely but participate in the attention which they obtain^

LETTER IV.

OPINIONS RESPECTING THE ORIGIN OF THESE BODIES.... PLASTIC
POWER.. ..TRANSLATION OF SEMINAL PRINCIPLES. ...GROWTH OF
STONES.. ..TERMS. ...FIGURED STONES. ...DILUVIAN STONES.. ..FOS-
SILS, EXTRANEOUS OR ADVENTITIOUS. ...NEW TERMS PROPOSED
....SECONDARY FOSSILS, VEGETABLE OR ANIMAL. ...FOSSILIA
VULGO DICTA.. ..IMPRESSIONS CASTS.. ..FIGURED STONES.

1 o stumble at the very threshold, is, I acknowledge, rather un-
graceful, and not very promising ; but remember, that sometimes,
the blame may lay in the stumbling block, and not in the man.
This, I trust, will prove to be the case, in the present instance. I
have to speak of substances, which, in my opinion, have never yet
been designated by appropriate terms ; and to treat of a science,
which has hardly yet acquired a peculiar name.

31

Until within these last hundred years, the nature of the sub-
stances, which form the subject of our present inquiry, was so little
understood ; that the most vague, and unphilosophical ideas, were
universally entertained respecting them. Men of considerable
learning, either contented themselves with the popular otions ,or,
substituted for them theories, still more silly and preposterous.
Thus our countryman Lhvvydd, in his Ichnographia Lithophylacti
Britannici, Langius in his Historia Lapidum figuratorum Helvetia ,
Dr. Plott in his Natural History of Oxfordshire, and numerous other
writers, so little suspected the real origin of these bodies, that they
described their peculiar forms as the sports of nature ; or attributed
their formation to the action of a certain Plastic power, destined to
the subterranean formation, of these regularly formed concretions.

So far was fancy indulged, whilst endeavouring to account for
their origin, that it was even supposed, as I remarked in my last,
that the seminal principles of various beings, raised by evaporation,
and carried by the air, or by subterranean currents, were deposited
in the several cavities of the bowels of the earth. These were sup-
posed to have grown, during an anomalous kind of life ; and to
have assumed a similar nature, with that of the particular matrix,
in which they had been deposited.

Others among whom Tournefort and Camerarius deserve parti-
cular mention, fully believed in the vegetation of stones : and were
convinced, that their seminal principles diffused, as well through
the seas, as the earth, were gradually developed, and reduced into
their appropriate forms, by a regular apposition of their particles ;
somewhat in the same manner, as in the formation of regularly
formed crystals. Every figured stone was supposed to have had
its peculiar seed, its nourishment, and its growth. The beautiful
and variously formed stalactites, which adorn the subterraneous
caverns of Derbyshire, and of many other parts of the world, were
supposed to be proofs of this species of vegetation; since their

32

volume was observed evidently to increase, and apparently in
determined forms.

From the total ignorance which subsisted respecting these sub-
stances, all the earlier writers contented themselves with employ-
ing words to describe them, which denoted their resemblance to
certain forms; describing them, generally, as FIGURED STONES
(lapides Jigurati fy lapides idiomorphi). Others who supposed they
owed their forms to certain extraordinary changes, which took place
at the period at which the earth was overwhelmed by the general
deluge, described them as DILUVIAN STONES (lapides dilumani).
But whilst they thus, with the utmost propriety, employed such
expressions as were, at least, not likely to mislead, they, of neces-
sity, were confined to such as were deficient in significancy.

But when the discovery was made, that most of these figured
stones were remains of subjects of the vegetable and animal king-
dom, these modes of expression were found insufficient ; and, whilst
endeavouring to find appropriate terms, a considerable difficulty
arose ; language not possessing a sign to represent that idea, which
the mind of man had not till now conceived. The nature and
origin of these substances had long been enveloped in the darkest
ignorance; and when sufficient rays of light had broken in upon
them, to enable the philosopher to view them more distinctly, he
plainly saw the important relation, which they bore to the history
of our globe ; and found himself engaged, in the contemplation of
objects almost unknown, and in the study of a science, entirely new.
This occurring, at so late a period, when language was fully esta-
blished and when every word had its peculiar office allotted to it ;
necessity drove him to the alternative of either, coining new words,
or of selecting, from those already in use, such as might be adopted
for the description of these substances.. The latter mode was pre-
ferred ; and the word fossil, which had hitherto been appropriated
to the whole of that class of bodies, which had been dug out of the

33

earth, appearing to approach the nearest to the idea, which was
wished to be conveyed, it was almost universally adopted to mark
this new order. But as confusion might arise^ from employing the
>nme word to describe both the class and the order, it was recom-
mended by Sir John Hill, for the sake of precision, to annex to the
word fossil, when expressive of the order, the epithet extraneous or
adventitious.

As none of the terms, hitherto enumerated, at all marked the
change which had taken place in the nature of the substance, this
was proposed to be expressed by adopting the term PETRIFAC-
TION. The prevailing practice with writers in mineralogy appears
at present to be, either the employment of the last mentioned term;
or the annexing one or the other of the adjectives (adventitious or
extraneous) to the substantive (FOSSIL,) whilst in the common lan-
guage of those most conversant with these substances, the idea is
conveyed by the substantive alone.

The more antiquated, and less significant of these modes of ex-
pression, do not demand any farther notice. Those alone, which
have been adopted since the discovery of the real nature, and origin
of these substances, demand that examination, which a convic-
tion of the necessity of establishing certain and determined modes
of expression, obliges me, with hesitation and diffidence, to under-
take.

PETRIFACTION*, a word very frequently adopted, is certainly
quite unqualified to be admitted, as the general term for these sub-
stances ; since it refers, only to a conversion into stone ; whilst the
changes, which actually take place, are of various kinds : and, in
some instances, as in pyritous fossils, the conversion is into a sub-
stance, almost as widely different from stone, as from the matter of

* Petrificata dicuntur vegetabilium vel animantium corpora, in substantiam fossilium
mutata. Gesner.

VOL I. F

34

which the body originally consisted. It, therefore, can be employed
to describe only that one particular species of fossils.

The word FOSSIL appears to be the only word our language can
supply, which is capable of being employed as the term denoting
these substances in general. The propriety of adopting it will appear,
when we consider its derivation, and the characteristics of the
bodies it is intended to signify. In the contemplation of these bodies,
three circumstances offer themselves for our particular notice : first,
their having been dug out of the earth ; secondly, their original
mode of existence ; and, thirdly, the nature of the change which
they have undergone. The term fossil, if its meaning be as-
sumed, strictly from its derivation, must be acknowledged to mean,
any mineral substance dug out of the earth ; but, when it is recol-
lected, that these bodies in general, exibit, to the senses, the most
obvious marks of their origin, and of the changes they have under-
gone, it is sufficient for the common purposes of speech, that
the word selected for them expresses their other grand character-
istic— their being dug out of the earth. But, although, when the
fossil body is itself present, and manifests to the senses, that for
instance, it was once wood, the applying to it the term fossil en-
tirely completes the idea ; yet this is not sufficient, in written lan-
guage, where the senses cannot thus supply, that which is defi-
cient in the term. Here appropriate epithets must be added, ex-
pressive of those parts of the idea, which are not already expressed.
The epithets extraneous or adventitious, proposed by Sir John Hill,
and generally adopted to the present time, are, in my opinion, ob-
jectionable ; not only because they do not comprise the two circum-
stances, which are required to be expressed ; but also because they
convey opinions respecting these substances, which a closer exami-
nation will show are ill founded.

The term extraneous denotes, that the substance spoken of is

35

foreign to the region in which it is found ; and is indeed, in a great
measure, applicable to most of these bodies ; to some, however, it
cannot, with propriety, be applied. While the body retains, not
only its primitive form, but also most of its original constituent
principles, the application of this term is, perhaps, admissible.; but
when its primitive form has entirely disappeared, and hardly an
atom of it remains in its original state of combination, the sub-
stance may be surely considered, as having undergone so complete
a naturalization, as no longer to admit the application of an epithet,
denoting its being foreign to the region in which it exists.

Adventitious, is an epithet still more objectionable ; since it not
only conveys the same idea as the foregoing word, but also denotes,
that the present situation of these substances, is the result of chance
or accident. The slightest suggestion of such an opinion demands
an immediate opposition ; for in all nature's works, there exist not
stronger proofs of the provident design of the almighty Creator,
than in this, apparently, casual disposition of these substances.
Adventitious, therefore, is a term, which in this instance, ought
never to be applied.

I will now proceed to offer, for examination, the nomenclature
which I am inclined to adopt, for the necessary distinction of these
substances. Should I, in doing this, be found to suggest terms not
sufficiently significant, I intreat that it may be considered, that I
have necessarily been limited in the exercise of my choice, by my
care and anxiety to avoid the coining of new terms ; or the making
of any unnecessary infringement on the language, which universal
acceptance has sanctioned.

The term fossil, so often vaguely employed, is in fact, the term,
describing all those mineral substances, which have been duff out of

O ' O

the earth. These I divide into primary and secondary, agreeable to
the generally accepted division of mountains. Under the PRIMARY
FOSSILS, I place all those substances which may be supposed to

36

be natives of, and to have existed primitively in, the subterranean
regions : such are the metals, stones of the granitic class, and most
of the various substances, of which the primitive mountains are
formed. Under the SECONDARY FOSSILS*, I place those substances,
which bear indisputable testimony, in their structure and form, of
their having existed in an organized state ; and which are therefore
known to have had an animal or vegetable origin ; but which have
afterwards entered into, and become, subjects of the mineral
kingdom.

SECONDAR-Y FOSSILS, which are alone intended to be the subjects
of our investigation, may, according to their origin, be divided into
two classes, VEGETABLE OR ANIMAL FOSSILS. Each class will be
found also capable of a further division, into orders, genera, and
species ; which classification although impossible to be made cor-
respondent with that of their recent analogues, will still, however,
yield some advantage in the prosecution of this study. The varie-
ties of the species can seldom be expected to be discoverable in
our specimens ; this term, therefore, may be adopted for those va-
rieties dependent on composition ; and which may be distinguished
by the epithets, appropriated to the several kinds of matter of
which they are formed; such as silicious, calcareous, aluminous,
bituminous, &c. Thus, I hope, without adopting any harsh or
offensive change, all confusion of terms may be avoided, and an
intelligible mode of expression secured.

It is proper to observe here, that I shall consider as fossil bodies,
some substances, which, by writers of considerable authority, have
been deemed unfit to come under that denomination. The sub-
stances which I here allude to, are those which, having lost, by the
decomposing powers of certain subterranean processes, not only all
the softer parts, but almost the whole of those principles which are
peculiar to animal or vegetable substances, seem to retain only the

* Transubstantiata, Linnseei.

37

earth of the bony lamellae, or of the ligneous fibre. These are the
fossilia, vulgo dicta, of Linnaeus. But since it is indubitable, that
the remaining principles have not only entered into intirely new
combinations ; but that new matter, as carbonic acid, &c. is super-
added, it must be allowed, that a degree of change, in the nature
of the substance, must have taken place. Other bodies have been
considered as secondary fossils, which, a slight examination will suf-
fice to shew, ought not to be thus classed. These are — 1st. IMPRES-
SIONS*. These are certain hard, but once soft, mineral substances ;
which retain the figure which has been impressed on them, by some
secondary fossil. 2dly. CASTS f. These are formed by the depo-
sition of mineral matter in the cavities of animal or vegetable sub-
stances, or in the vacuities, left by the decay of organized bodies,
involved in some solid matrix. 3dly. INCRUSTATIONS f. These
are formed by such an apposition of mineral matter generally by
precipitation or deposition, as effects the envelopement of some
vegetable or animal body, in a mineral crust.

Whatever claim to this distinction the two first mentioned of these
bodies may possess, from the circumstance of their actually owing
their form to secondary fossils, it must be, rejected ; since they
merely bear the form, and were themselves never endued with ve-
getable or animal organization. With respect to incrustations, the
last-mentioned of these bodies, it is sufficient to remark, that the
circumstance of incrustation alone, is not sufficient to constitute a
body, fossil ; since organic bodies, thus found, are, generally, of
but a late origin, and, most frequently, unaltered in their structure*
Due attention will, however, be paid to all these substances, when-
ever they serve to illustrate the actual secondary fossil ; or contri-
bute to the explanation of its mode of formation

* Impressa, Linnsei ; Typolithi, Wallerii ; Type and Ectype, Breynii ; Figuratorwn
Lapidum Matrices, of others.

t Rcdintegrata^ Linnaei ; Petrificata spoliata, Luidii, Noyau, Galloruna.
J Incrustata,

38

Besides the bodies already mentioned, we shall have, occasion-
ally, to notice certain FIGURED STONES *, which independent of
the interference of any animal or vegetable body, present the re-
semblance of some body, not of the mineral kingdom. When this
is the result of the fortuitous concurrence of certain marks on the
surface, they have been termed lapides picti, and graptolithi ; and
when the resemblance depends on the whole external form, they
have been named lithoglyphi.

Should our old friend Wilton complain of this letter being too
dry and unentertaining, remind him, that unless our terms are de-
fined, there never can be a hope of our obtaining a good under-
standing. Promise him, that our pursuits shall yield him a large
stock of entertainment, with a full share of the marvellous. Assure
him, that he shall hear

-Of antres vast, and deserts idle,

Rough quarries, rocks, and hills, whose heads touch heaven. Shakspcare.

Tell him, that I hope his faith will be comprehensive enough to
enable him to receive, with full credit, the accounts delivered by Bap-
C tista Fulgosus, Ludovicus Moscardus, and Theodorus Moretus, that
a whole ship, with its anchors, broken masts, and forty mariners,
with their merchandize, were found, in the year 1460, in a mine
fifty fathom deep, in the neighbourhood of Berne, in Switzerland f .
Relate to him, that Valchius, in his commentary on the Klein Baur,
tells us of a truly curious fossil man, found at Maria Kirch, near
Strasburgh, by a miner, who, breaking open the hollow of a rock,
was astonished at beholding the figure of an armed man, standing
upright, composed of a mass of silver, of five hundred pounds
weight. If his interest and astonishment be not hereby sufficiently

* Lapides figurati—Lithomorphi, Wallerii.

t Musco di Ludov. Moscardo. lib. ii. cap. 3 Theodor. Moreti. tract, de JE&tr.
Maris, cap. 21. Baptist. Fulgosi Diet. & Fact. Mem. Collect, lib. i. cap. 6.

39

excited, tell him, we have more tales of wonder in store ; of flocks
of cattle, of large companies of men, and of even whole cities, with
their inhabitants, converted to stone*. I could supply him, from-
a comparatively modern author, with an account of a troop of Spa-
nish horsemen, who thus underwent the process of petrifaction -f ;
and with a very seriously attested relation of a petrified child, which
was shewn at Paris, and which was, occasionally, used by its pos-
sessor as a whet-stone £ !

Yours.

LETTER V.

FORM OF THE EARTH^S SURFACE... .MOUNTAINS.. ..STRATA, ...WIS-
DOM MANIFESTED IN THEIR DISPOSITION. ...DIFFERENT KINDS
OF EARTHS. ...ALUMINE ; FORMING CLAY, LITHOMA'RGA*

£c.... SILICA; FORMING ROCK CRYSTALS, CALCEDONY,
&C....LIME ; FORMING LIME-STONE, CHALK, TUFA, MARBLE, &C.
....MAGNESIA; FORMING STEATITES, ASBESTOS, SERPENTINED
&C....SULPHURETS, PYRITES, OR MARCASITES.

J MUST intrude on your patience, with one letter more of intftK
ductory matter ; it being necessary, before we speak of secondary
fossils themselves, to give a cursory account of the matri€es9in which
they are found : and of the substances, of which both they, and the
fossils themselves, are formed.

* Aventini, lib. vii. Annal. Boiorum. Purchas's Pilgrimage* jfc 24fv
t Jos. Acosta, lib. iii cap. 9. t Vide Helmont de Lithiasi

40

The globe which we inhabit, presents, every where, a surface,
more or less irregular. In some places, gentle risings and declivi-
ties only are found : in others, the elevations are vast and lofty ; and
are accompanied by proportionate vallies. In some parts, the dry
land, interrupted only by slight intersections, for the currents of
rivers, stretches into immense continental tracts ; whilst in others,
prodigious excavations, of the substance of the earth, serve as the
receptacles of immense oceans of water. These, it is allowed, ex-
ceed, in the sum of their extent, that of the dry land ; and bear a
very near proportion, in their depth, to the height of the loftiest
mountains.

Mountains are with propriety, divided into primitive, or prime-
val ; and secondary, or epizootic. The primitive and secondary
mountains differ, not only in their composition, but even their
form.

The primitive mountains are composed of granites, and of stones
of the granitic class, of porphyry, jasper, serpentine, sand-stone,
trap, and sometimes, but more rarely, of lime-stone, fluors, gypsum,
&c. These substances, sometimes, lay in strata; but, most fre-
quently, they are found in huge blocks ; thus a granite mountain,
about thirty miles from the Cape of Good Hope, called the PEARL
DIAMOND, rises out of the ground, to the height of about 400 feet,
being half a mile in circumference ; and formed of a single block
of granite. These mountains never cover secondary mountains,
but are often covered by them. They are commonly the highest
ridges in any chain, and terminate, generally, more narrow and
sharp, than the secondary.

The most distinguishing character of these mountains, is a cir-
cumstance which particularly demands our attention — no organic
remains are to be found, in the interior part of the substance of
the stones of which they are composed.

41

Secondary mountains are, generally, marked by a softer outline ;
and frequently possess the distinctive character, of being composed
of, or at least, of containing within them, the fossil remains of
organized substances. They always rest on, and sometimes cover
primary mountains ; and very commonly, also, they lean on their
sides, or invest them. The secondary mountains are formed, like
the primitive ; of either one species of stone, or of strata of different
species. Some are said to be derivative, being supposed to have
originated from the disintegration of primitive mountains.

The substances, of which the secondary mountains are chiefly
composed, are lime-stone, swine-stone, marlite, chalk, and gypsum.
They are also, sometimes, formed of indurated clay and lithomarga,
jasper, porphyry, trap, silicious sand-stone, and other substances,
which belong also to the primitive mountains.

The various strata of which the earth is composed, as deep as the
curiosity, and the necessities of man, have induced him to explore
them, manifest, in a most striking manner, the wisdom displayed in
the arrangement of the materials which compose the present world.
The first layer, generally consisting of a rich black mould, is formed
almost entirely of the remains of innumerable animals and vegeta-
bles, which, having lived through their destined periods, have been
resolved into their first principles. This substance, laying at the
surface, where alone it would be of utility, yields sustenance to the
vegetable kingdom ; and thereby becomes the support of man, and
of the rest of the animal creation. Beneath this, is most com-
monly found, a thick bed of clay, which furnishes the matter of
which bricks and tiles, with the various species of pottery, and
innumerable other articles, adapted to promote the comforts of
social life, are formed. Next to this, in general, vast beds of gravel
appear, composed of pebbles ; varying much in their size and form :

G

42

and with this is also commonly found the fine gravel ; which like-
wise varies, in different parts, in its degree of fineness, and in its
colour. Underneath these, in many parts, are the infinitely vary-
ing strata of sand-stone, lime-stone, &c. which serve, with the
trunks of trees, which have grown in, and which have been nourished
by, the first layer; and with the bricks and tiles, made from the
second layer, to supply the materials, of which the dwellings of
man may be composed. They also serve, with the sand and gravel
of the third stratum, to supply that kind of surface to the earth,
which may best expedite the intercourse, which must, necessarily,
take place between the inhabitants of distant parts. These strata
of stone, varying perpetually in their colour,, solidity, and texture,
form, in some places, the ceilings and floors of the vast subterranean
caverns, which are found in various parts of the world ; and which
often contain, as do those, particularly, in the principality of Bay-
reuth, and in the Hercynian forests, very interesting specimens of
those remains, which are the objects of our particular research.
They also form the surrounding parts of those mines, which contain
the valuable metals, which civilized man forms into innumerable
articles of utility, and of ornament. Beneath schistose or slaty
strata, are generally found the immense beds of coal, so necessary
to the comfort, and in some situations, even to the existence of man.
These strata do not always follow each other in regular order ; since
sand and gravel are, sometimes, found at a considerable depth, and
trap, or rag-stone, is often interposed between them, in various di-
rections.

In almost all these strata, even to a very considerable depth, the
remains of vegetables and animals, which have existed in former
remote periods, are frequently found : and, in general, possess
the same physical and chemical properties, and are composed of
similar constituent parts, with the strata themselves. What these

43

constituent parts are, becomes, therefore, an object of necessary ex-
amination.

Of the first stratum of mould, sufficient has been already said

for our present purpose.

Clay, which I have reckoned the second stratum, has for its basis,
the earth called ALUM IN E, or the earth of clay, which constitutes
its real argillaceous part. This earth readily combines with acids,
and forms the salt called alum, by its union with the sulphuric acid
or the acid of sulphur. It hardens to a very considerable degree
in the fire; but does not fuse, unless combined with lime, or certain
salts containing the phosphoric acid. The other ingredient, in the
formation of clay, is silicious sand, of which I shall presently speak
more fully. From the various proportions of these two substances ;
from the different degrees of their- respective purity ; and, particu-
larly, from the admixture of iron, and of some of the other earths,
proceeds a considerable variety in clays. Those which are most
likely to come under our observation are, the lithomarga, formed by
the finer clays in various degrees of induration ; and fullers earth,
an argillaceous substance, deriving a saponaceous softness from its
containing a small portion of magnesia.

Trap, rowley rag, toad-stone, or wacken, are stones in which argil-
laceous matter very much predominates. These, from the manner
in which they are diffused through the subterranean regions, and
from the peculiar structure which they possess, have been errone-
ously supposed to be of volcanic origin.

Schistus or slate, is also a mixture, in which alumine very much
predominates. It also contains the earth of flint and magnesia. It
is found to vary considerably in colour and texture, according to
the degrees of purity, and the different proportions of its constituent
parts.

SILICA, or silicious earth, the earth of flints, is the chief consti-

44

tuent of the pebbles and sand, which form the third stratum I have
mentioned. It is difficultly acted on by any acid, except that
which is obtained by distillation from Derbyshire fluor spar ; and
which is termed fluoric acid. It is, however, very powerfully acted
on by the alkalies, which promote its fusion, and, when thus com-
bined with it, in a certain degree, form glass. It is this earth, which
chiefly forms the common flint, and horn-stone ; the more pure chal-
cedony ; and the still purer quartz, or rock crystal; the variously
figured agate; the arborised mochoa; the beautifully marbled jas-
per ; the sportive Egyptian pebble ; and the finely veined wood-
stone, still retaining the mark of every fibre, which regulated its
pristine structure. Combined with a certain portion of alumine,
it forms the chief constituent of the amethyst, topaz, and various
other stones, which, from their brilliancy, hardness, and colour,
are estimated as gems. This earth, also, chiefly helps to constitute
the granite,, of which the primitive mountains are formed. This
stone frequently displays, in a most beautiful and distinct manner,
the three substances of which it is composed. 'The feldspar, the con-
stituents of which are silica, alumine, and magnesia, will be seen,
generally, in oblong, curd-like masses, of various sizes. The mica,
composed of the same constituents, but in different proportions, will
appear generally in grains about the size of a pin's head, of different
colours, but, most commonly, black ; and sometimes in white flakes
of a metallic lustre. The quartz will be found interposed between
these generally of a greyish colour ; and appearing to be the me-
dium by which the other two substances are agglutinated together.
LIME is the earth which chiefly forms the various lime-stones,
which are placed, in different layers, beneath the beds of clay and
sand. This earth is rendered tolerably pure, when, by intense heat,
it is made into quick-lime. It fuses, when combined with flint and
clay ; and readily combines with acids. It is soluble in 700 times

45

its weight of water, forming tbe liquid called lime-water. From its
caustic qualities, and its solubility in water, is now generally consi-
dered as an alkaline substance.

From the combination of lime with carbonic acid ; the acid which
is formed by the union of carbon, the chief matter of charcoal and
of the diamond, with oxygen or the acidifying principle, proceeds
carbonate of lime. From this substance, according to its dfferent de-
grees of purity, and modes of combination, is formed chalk; a sub-
stance which requires no description — Tufa, a light porous calca-
reous substance, chiefly deposited from water, in which it had been
diffused — Lime-stones, of various colours and texture, employed for
paving, and for various purposes of architecture — Marbles, which
are finer kinds of lime-stones, possessing a closer texture, and being
capable of assuming a good polish — Calcareous spar, named accord-
ing to the form of its crystals, lenticular spar, dog-tooth spar, &c. —
Alabaster, formed by the deposition of calcareous matter in clefts of
rocks, from the water in which it was suspended — Stalactites, formed
on the roofs of subterranean cavities by the gradual accretion of si-
milar matter, from water filtrating through the more porous lime-
stone; and Stalagmites, formed by the deposition of the same mat-
ters on the floors of caverns.

By the mixture of lime with clay, are formed the various marls ;
existing, sometimes, in •& soft and pulverescent state, and at other
times, possessing the hardness of stones.

By the union of sulphuric acid with lime, is formed gypsum, or
selenite, a substance generally of a white colour, and exhibiting a
slight degree of lustre and transparency. By intense heat, the lime
is obtained from this substance, in a state of considerable purity ;
and is then termed plaster of Paris. When combined with the acid,
termed fluoric acid, the substance called^wor spar is formed ; which
is so well known to you, by the more common name of Derbyshire
spar.

46

With the phosphoric acid, an acid originating, perhaps, in the
animal kingdom, lime also frequently combines, to form phosphate
of lime. By this combination, is also formed phosphorite* a stone
found in large masses, chiefly in Spain and in German}7.

Lime has been supposed by those of high authority, to have been
entirely of animal origin. This, however, cannot be admitted; al-
though it is indubitable, that a considerable portion of it has pass-
ed through the animal kingdom : vast masses existing of animal re-
mains, resolved into this earth, which still retain sufficient of their
previous structure, to point out the form they had originally
borne.

MAGNESIA is a very light substance, and soluble in about 2000
times its weight of water. The various stones, in which magnesia
predominates, almost always show its presence, by a smooth and
unctuous feel ; this is particularly, the case with the various steatites,
or soap-stones. They also sometimes manifest a flaky structure, as
is the case with common talc. Sometimes they display a striated
texture, with a lustre of the silky kind, as in the amianthus, and in
the asbestos; the stone, from which may be made incombustible
cloth. Serpentine, a stone which, from the disposition of its colours,
is supposed somewhat to resemble the skin of a serpent ; and which
has rather a soft, and somewhat of a greasy feel, with a silky lustre,
is composed of this earth, with a certain quantity of silica, and a
very small portion of iron.

SULPHURETS OF METALS, and particularly that of iron, found at
various depths, and frequently entering into the composition of se-
condary fossils, demand a few words. These are the substances
more commonly known by the name of pyrites, or marcasites, and
are formed by the intimate union of sulphur with some of the rne-
tals. They, in general, shine with a brilliant metallic lustre : and
when they do not, they frequently suffer decomposition, on exposure
to the action of the air.

47

The other chemical substances, which 1 shall have occasion to
speak of, as performing a considerable part in some of those extra-
ordinary transmutations which will come under our observation, I
shall strive to treat of, in the places where they occur, with that
plainness, which will render it unnecessary to take up your time
further at present ; it being my intention to introduce, with as little
interruption as I can to the main subject, such explanatory obser-
vations as, I hope, may secure your full comprehension.

Yours, £c.

LETTER VI.

PLEASURES OF TRAVELLING.... WOOD-STONE. ...INQUIRIES RE-
SPECTING VEGETABLE FOSSILS.

THE pleasures of travelling were never, perhaps, more completely
experienced than by our little party ; since, by carefully avoiding,
as much as possible, the limiting ourselves to any particular time,
for the performance of our several stages, we are not prevented from
embracing every opportunity which offers, of examining whatever
appears to be curious and interesting. Thus unconfined, we seldom
fail to stop, to make the necessary examination of whatever appears
to have a fair claim on our attention.

A few days since, passing along a road, which traversed the skirt
of a very stupendous mountain, we united in expressing our admi-
ration of the delightful situation of a few exceedingly neat cottages,
placed by the side of the road, under the mountain. The beauty of
this sequestered spot, and the extreme neatness of the cottages,

48

induced us to quit, the chaise to have a nearer view of this charming
spot.

We had not long alighted, before a gentlewoman, about forty
years of age, of a genteel and pleasing appearance, who was at
the window when the carriage stopped, advanced to us from the
house, which had most particularly excited our attention ; and, in
the most polite manner, requested us to favour her with our com-
pany, and to partake of some refreshment. The invitation was too
welcome to us to be rejected ; we, therefore, cheerfully accompa-
nied her into the house ; the inside of which manifested the same
neatness, and the same display of taste, which we had already wit-
nessed. Showing us into a parlour, she in a very frank manner in-
formed us, that we were now in the vicarage house, pointing to the
church, at about half a mile distance ; and informed us, that her
husband had performed the duties of this cure, nearly ten years.

This information, so well calculated to give us confidence in our
new acquaintance, demanded a similar frankness on our part. We
therefore stated who we were ; and that a wish to contemplate the
various beauties of nature's works, had chiefly incited us to this jour-
ney. Mutual confidence being thus established, our kind hostess
informed us, that, as the sun would soon set, and as there was no inn
which could receive us, within fifteen miles, she must intreat our
promise to take up our abode there that evening. This, she said,
was a request, in which Mr. Inman would most heartily join her;
nay, she added, he would not forgive her if she had failed, in se-
curing him the pleasure of such agreeable. society.

The tea-things were soon arranged, and our kind hostess placed
us in the bow-window, from which we were gratified, with an unin-
terrupted view of a very extensive plain of country; stretching from
the foot of the mountain, as far to the west as the eye had power to
distinguish. The sun having now declined, almost to the horizon,
not only covered that part of the heavens with his effulgent golden

tints ; but also beautifully painted the tops of the little cottages,
and scattered hamlets, which variegated the plain before us; thus
helping to complete the charms of this delightful scene.

We were engaged, in viewing this prospect, when the door
opened, and the master of this charming little mansion made his
appearance, carrying in his hand a bundle of rough, misshapen frag-
ments of wood. After having disposed of these, with much more
care than to us appeared to be necessary, on a marble slab, which
served the purpose of a sideboard, he was introduced to us by his
lady ; whose request for our stay that night, he seconded with so
much urgency and politeness, as to induce us to accept the kind in-
vitation with the utmost alacrity.

Our conversation soon became so familiar, and assumed such a
cast, as to make it appear, that we had all become actuated by the
same wish, to prevent any of the short time we had to pass together,
from being wasted in the dry and unmeaning language of ceremony.
Freedom and hilarity marked the mutual pleasure experienced by
our little party. Emma and Mrs. Inman were engaged in conver-
sation, respecting the neighbouring country ; and Mr. Inman,
doubtlessly perceiving the many looks of curiosity which our friend
Winton had bestowed on the bundle of wood, which still occupied
a situation, in his opinion, ill fitted for its reception, informed us,
that he had been traversing the mountain, the whole afternoon;
and that little bundle was the only fruit of his labour. "I suppose,
Sir," said Winton, eagerly catching at an opportunity of gratifying
his curiosity, " that fuel then must be very rare in these parts."
Mr. Inman smiling, fetched the little bundle, and put it into
Wlnton's hand ; whose looks directly manifested very strong marks
of surprise, bordering indeed on alarm, from the circumstance of
his having, from the unexpected weight of the parcel committed
to his charge, nearly let it fall to the ground.

When he had a little recovered himself, he requested Mr. Inmao
VOL. i. H

50

to inform him, what kind of substance this was. " It is," said Mr.
Inman, " a species of fossil wood, which we, sometimes, find on
digging in different parts of this mountain." u Wood !" exclaimed
Winton, turning round, and depositing the parcel in my hands for
my examination, "why really it is as hard and heavy as any stone
I ever felt !" " By fossil wood," said Mr. Inman, " I mean that
which was once wood, but which is now become stone." A closer
examination now showed me, that this substance was more truly
curious, than it had even appeared to be on a superficial view ; since
I discovered, that its resemblance to wood consisted, not merely in
its general external appearance, but that this similitude was disco-
verable, in its internal structure : the knots, the concentric lamina,
and even the smallest fibres of the wood, being perceptible. Per-
ceiving our attention to be so much engrossed by this curious sub-
stance, which appeared to us of such an ambiguous nature, Mr.
Inman remarked, that as the evening was too far advanced to allow
any excursion on the mountain, he would endeavour to amuse us
with a little cabinet, containing some curious smaller specimens of
a similar kind ; some of which he had acquired, during his travels
OH the continent. We soon surrounded the table, on which he, in
turn, placed several drawers, containing a considerable number of
beautiful and interesting specimens, of what, according to the sug-
gestions in your obliging letters of instruction, we should name,
vegetable fossils. Not only did I never before view a collection
so interesting; but I never had even conceived that there could
exist in bodies of this kind, so much beauty ; or that substances,
indubitably of a mineral nature, could possess, so distinctly, the
characteristic forms of vegetables.

One specimen, which, as it lay in the drawer, was not to be dis-
tinguished from a well smoothed piece of common deal, possessed
so great a degree of hardness, that on being struck against a piece
of steel, sparks were produced, exceeding in number and brilliancy ?

51

those which proceed from ordinary gun-flint. Another piece pos-
sessed the blackness of ebony, and had as high a degree of polish, as
the smoothest glass. Another specimen was almost entirely invested

with a crust of most brilliant crystals. Another-^ but I must not

pretend to describe the various beautiful and astonishing objects I
beheld. So great was the variety which passed before my eyes, and
so much was my mind engaged in forming fruitless conjectures,
respecting the ambiguous nature of these wonderful bodies, that my
recollection of them is rendered confused, and my total ignorance
respecting them, prevents my possessing appropiate words to form
their description.

I was mortified to find that Mr. Inman, himself, was not able to
furnish me with any real information respecting them : he merely
stated it to be his opinion, that they had been buried ever since the
days of Noah ; and had, by the great length of continuance under
ground, suffered this surprising change.

On a subject so exceedingly interesting, the mind, not satisfied
with vague conjecture, seeks for somewhat like explicit information:
or is, at least, anxious to ascertain, how far investigation has been
successfully employed, on such questions as may tend to explain,
how vegetables could thus be converted into the hardest stone ; or
by what means they could be preserved, during so long a period, as
that which must have existed, between the time of their commit-
ment to the earth and of their transmutation.

On the following morning, our kind host conducted us up the
mountain, and showed us the spot where, on the day before, he
had found the pieces of wood we had seen. We, therefore, eagerly
set to work, here, with a small mattock, which he had purposely
provided, and were so fortunate as to find two or three good speci-
mens, which, I assure you, we carefully preserve, purposing to add
them to your collection ; but on this condition, that, in your next

52

letters, you favour us with some information, respecting these won-
derful bodies, which have actually passed, from the vegetable to the
mineral kingdom.

Yours, &c.

LETTER VII.

1 (

VEGETABLE FOSSILS.. ..FOSSIL TREES. ...DESCRIBED BY THE AN-
CIENTS....BY THE MODERNS. ...FOUND IN ALMOST EVERY PART

OF THE WORLD.

•

JT has been my endeavour, in my preceding letters, to furnish you
with some general and useful notions, respecting secondary fossils
in general ; as well as with some general account of those . sub-
stances, which will be found most frequently concerned, in the im-
portant changes which secondary fossils have undergone.

VEGETABLE FOSSILS, will now, very properly, according to the
arrangement I have adopted, become the subjects of our investiga-
tion. This also will be the proper moment for their consideration ;
since the curious phenomena you lately beheld, have, it is very evi-
dent, excited your curiosity and interest, respecting their particular
changes, to a very considerable degree.

Vegetable fossils *, I shall divide into the following orders : —

* Phytolithi, of Linnaeus and Wallerius.

53

1. FOSSIL TREES*.' — 2. FOSSIL PLANTst. — 3. FOSSIL ROOTSJ. — '
4. FOSSIL STALKS ||.— 5. FOSSIL LEAVES§. — 6. FOSSIL FRUITS
AND SEED VESSELS^-

With respect to FOSSIL TREES, as well as with respect to every
other fossil of which I shall treat, I shall adopt that which appears
to be the mode best adapted to excite your interest, and to secure
to you every necessary information. I shall endeavour to supply
you with an historical sketch of what has been, hitherto, made
known respecting them ; to state the several theories by which it .
has been proposed to account for their origin ; and lastly, to lay
before you the facts, which later observations have discovered, and
the opinions which these appear to warrant.

That the existence of fossil trees was known, in very remote pe-
riods, there cannot exist the least doubt ; but no rational opinion,
respecting their nature or origin, has been offered until modern
times. Theophrastus** speaks of a stone, bearing in its external
appearance, a resemblance to rotten wood. Straboft relates that
trees, much resembling the laurel and the olive, were buried in al-
most the whole of the mouth of the Red Sea ; which during the
ebb, were sometime exposed, and which, during the flowing in of
the tide, were sometimes torn up. This, he observes, is very asto-
nishing ; since, even higher up in the country, no trees are to be
found. Eratosthenes relates the same circumstance, as observable,
in the Persian Sea. PausaniasJJ mentions a fossil wood, which

* Phytolithi Arborum, of Linnaeus ; Lithoxyla, of Wallerius ; and Stelechites and Den-
drolithes, of others.

t Phytolithi Plantarum, of Linnaeus ; and Plants petrificatae, of Wallerius

J Rhizolithi, of Wallerius. H Lithocalami, of Wallerius.

§ Lithophylla, of Wallerius ; and Lithobyblia, of others.

^j Carpolithi, of Wallerius ; and Spermolithi, of others.

** Theophrast. I1EPI TQN AI0QN. sect. xxix. ft Strabon. Geograph. lib. xvi.

tJ Pausanias, Graeciae Descriptio, lib. i. cap. 43.

54

was considered as fossil ebony. Referring to a certain statue
formed of ebony, he says, he heard from a man of Cyprus, exceed-
ingly learned in the properties of plants, that ebony never put forth
either leaves or fruits, nor ever showed a trunk above ground,
Agricola*, also notices this supposed particularity of ebony, add-
ing, that its external appearance is similar to that of jet; from
which, however, it differs in being but little affected, whilst jet
burns, and is consumed, in the fire. A piece of this kind of ebony,
he says, was once presented to him as a branch of black coral.

There is, perhaps, no part of the known world, in which the mi-
neralized remains of trees have not been discovered. According to
Agricola-f-, very large trunks of firs have been dug up in different
parts of Germany, turned, with their bark, into stone ; the crevices
of which were filled with golden coloured pyrites, or marcasites.
Similar trees, with branches, have also been dug up near Cracow,
which, when cut into the'form of whetstones, were sent as presents
by the barons, who held the territory, to Ferdinand the king of Bo-
hemia. He relates, that he himself saw, in a pool near the castle of
Robestein, in Misena, many trunks of trees, which were changed
into stone. In the earth from which the alum is obtained, near
Hildesheim, oak trees were found converted to stone; and in the
same country, near to the castle of Mariaburg, he mentions a hill
full of logs in a petrified state. These are very long, and seem as
if they had been placed together in heaps; their stony hardness
fceing rendered sufficiently evident, on being struck by a piece of
iron, or another stone. In the aluminous earth of Hildesheim is
ajso found the fossil wood, which, as has been just observed, has
been considered as fossil ebony.

Agricola, whose actual researches were such as must have fur-
nished him with numerous opportunities of determining, that this
astonishing change of wood into stone did actually take place ; but,

* Agricola, De Natura Fossilium, lib. viii. p. 324. Basileae, MDLVIII, t Loc. cit.

55

at the same time, being influenced by the predominant opinion of
that period, that nature amused herself by modelling, in stone, imi-
tations of the forms of organic bodies, he thus endeavoured to fur-
nish a mode of distinguishing in which of these classes, the stony
substances bearing a vegetable form, are to be arranged. As nature,
he says, generates stones, resembling trees, it must be diligently ob-
served whether they possess the bark, pith, &c. since if these are not
discoverable, it may be concluded, that they are not trunks of trees
converted to stone, but that nature has formed those stones, to re-
semble the trunks of trees. Thus he says, respecting the piece of
timber found by Jovianus Pontanus, in the promontory of Pausi-
lypus, in consequence of a part of the rock being broken off by the
violence of the storm, we cannot determine, as these particulars are
not explained, whether it was a stone which only bore the form of
a piece of wood, or whether it was actually wood, converted into
stone.

Thus also Kircher, speaking of petrified woods, observes, there
are some which formerly have been wood, and have been converted
into stone by the long course of time, or by the influence of the la-
pidific power. Others there are, which cannot be said to derive
their origin from a vegetable nature ; except in some very remote
way, but were thus formed from the first*.

De Boot relates, that near Bruges in Flanders, upon digging, to
the depth even of 50 feet, whole forests were found ; the leaves, and
the trunks being so little altered, that, the different species of the
trees might be ascertained ; and even the different series of leaves,
which had fallen yearly, might also be distinguished •)-. Schoockius
also observes, that large trunks of fossil trees are dug up in diffe-
rent parts of Germany ; particularly in Poland, near Bois-le-duc, in

* De Natura Fossilium, lib. vii. p. 324. Basil. MDLVITT. Kircheri Mund. Subt. lib. viii.
cap. 6.

t Gemmarum & Lapidum Historia, lib. ii. cap. 158.

56

the province of Brabant ; and, according to Glaus Wormius*, they
have even been found in the loftiest and most craggy mountains of
Iceland, and in almost all the maritime parts of Holland, Fries-
land, Zealand, &c. Subterranean trees have also been found by
Franciscus Stellutus, not enveloped merely in earth, but in stone.
In Misnia, a beech tree, with all its leaves and branches, was found
in a stony stratum, a hundred and eighty ells deep. In the valley
of St. Joachim, at a considerable depth, was found an oak,
with its roots and branches, in a petrified state, according to
Leibnitz -f. Both Gesner and Albinus mention a beech having
been found which was afterwards formed into whetstones. Leib-
nitz also mentions a stone, which was in the possession of Benjamin
Olitsch, an ingenious miner; and which he had procured from Au-
gustoburg, in Misnia, which would be directly known to have been
part of an alder.

Buffon relates, on the authority of Rammazini, that for four
miles round the town of Modena, wherever the earth is dug to the
depth of 63 feet, if the workmen pierce about five feet further, with
a boring instrument, the water rushes up with such impetuo-
sity, that it fills the wells to the top, almost instantaneously. The
water in these wells continues perpetually ; and is neither augmented
nor diminished by rains or drought. It is still more remarkable,
that on this spot, whenever the workmen dig to the depth of 14
feet, they find the rubbish and ruins of an ancient city, paved
streets, houses, and different pieces of Mosaic work. Below this,
the earth is solid, and appears not to have been moved. Still lower,
they find a moist soil, mixed with vegetables ; and at the depth of
26 feet, entire trees, as filberds, with nuts upon them, and great
quantities of branches and leaves. At 28 feet there is a stratum of
soft chalk, 11 feet thick, mixed with sea shells ; and after this they
again meet with vegetables, leaves, and branches of trees, till they ar-

* Lib. ii, cap. l£. f Leibnitii Prdtogaea. Getting, sect, xlv-

JH 5?

rive at the depth of sixty-three feet ; where there is a stratum of
sand, mixed with gravel and shells, similar to those which appear
on the coasts of Italy. These successive strata lie always in the
same order, wherever pits have been dug ; and, sometimes, the
boring instruments fall in with trunks of large trees, which the
workmen pierce with great labour : they likewise meet with bones
of animals, pit-coal, flints, and pieces of iron. Ramazzini, who re-
lates these facts, thinks, that the Gulf of Venice formerly extended
beyond Modena ; and that this land, in the progress of time, has
been gradually formed by the rivers, assisted, perhaps, by inunda-
tions of the sea *.

In the Isle of Anglesey, subterranean trees are frequently dug
up ; and in the Isle of Man is a marsh, called Curragh, six miles
long, and about three broad, in which subterranean fir trees, in vast
quantities, are found : and though eighteen or twenty feet below
the surface, they appear as if standing firm on their roots.

Subterranean trees are found in various parts of Ireland, particu-
larly in the morasses ; but the greatest attention has been excited
to the wood, actually in a petrified state, which is found in the
neighbourhood of Lough Neagh.

Dr. Boates, in his account of Lough Neagh, relates, that on the
borders of that lough are found little stones, of a pretty moderate
length ; some of them round in their compass ; others flat, or flat-
tish ; and some angulous : and which being looked on, as well near,
as from afar off, seem to be nothing else but wood ; and by every
one are taken for such, until one come to touch or handle them :
for then, by their coldness, hardness, and weight, it appeareth that
they are not wood but stone. But with respect to wood, placed in
the lake, being turned by its water into stone, he says, he had never
been able to learn the fact, from any persons who had themselves

* Buffon's Natural History, vol. i. p. 481.
VOL. I. I

58

tried this matter; but several affirmed, that it had been done by
others of their acquaintance *.

Mr. Wm. Molyneux, secretary to the society of Dublin, for pro-
moting researches in natural philosophy, believed in the petrifying
power of Lough Neagh, in opposition to those who asserted, that
the petrified wood is found in the sand hills near the lough. He
also thought this power was chiefly exerted on the holly ; but he
never obtained any positive proof of this property existing in the
waters of the lough ; nor could he procure a piece of petrified wood,
with unchanged wood adhering to it. He observes, that when
briskly calcined, the ashes of this petrified wood were affected by
the magnet •(-.

But Mr. W. Smith, whose opportunities of observation were fre-
quent, says, in answer to some queries proposed to him on this sub-
ject by Mr. Molyneux, that he thinks the petrifying power of
the waters of the lake .to be fabulous ; and believes, that the petri-
fied wood is found, only in the earth which surrounds, or which
forms the bed of the lake, at the sides. He remarks, that none of
the pieces he saw, were partly wood, and partly stone ; nor did he
ever see the bark petrified.

This wood is described, by Dr. Barton :f, as existing in two dif-
ferent states. In the one kind, there is still an exact resemblance
to wood, although it is now really stone. This is, generally, in small
pieces, which are of a whitish colour, porous, and comparatively
lighter than other stones; cleaving easily lengthways, grinding
to a smooth surface, so as to be fit to whet knives; and have
never yet been found with any wood contiguous to them. The
other sort is found in much larger, harder, and more weighty pieces,

* The Natural History of Ireland, by Dr. Gerard Boate, published by Hartlib, in
1652, and republished in 1755.

t Philos. Trans. No. 158, p. 554.

% Lectures in Natural Philosophy, &c. by Richard Barton, B. D. Dublin, 1151.

59

which are black, both externally and internally. This sort is fre-
quently found with much wood on the surface of the stones ; and,
most frequenlty, the internal parts of the stone are found to con-
lain wood still existing in a soft state. Of this kind, two very large
pieces are mentioned. The one was a stone, weighing 700 pounds,
which was found two miles from Lough Neagh, on the side towards
the river Camlin. This specimen appears to have been, externally,
complete stone ; but internally, evidently woody. The other speci-
men was as heavy as two men could lift, and the reverse of the for-
mer : the outer coat being of a woody nature, and the internal part
entirely stone. The woody coat of this stone, when first found, was
at least a foot thick, except at the ends. The stony parts of these
masses are of a dark grey, approaching, in some parts, to a blue co-
lour ; but are generally stained yellow on the outside, from their
laying in a bed of gravel.

These stones are chiefly found at a point called Ahaness, in the
county of Antrim ; half a mile south of the mouth of the river Glen-
evey. The bank at Ahaness is twelve feet high ; between the bottom
of which and the lowest water-mark in summer, there is a space of
about ninety feet; which space, in winter, is sometimes covered with
water.' Upon digging a pit in this place, it appeared that the
upper stratum is of red clay, four feet deep ; the second stratum is
of stiff blue clay, four feet deep ; the third stratum is formed by a
black wood, lying in flakes four feet deep; and under this is clay
again. From the top of the stratum of wood to the surface, is a
depth of seven feet ; and before the water of the lake encroached so
far on the land, it appears to have been nineteen feet.

In a paper of Mr. James Simons, contained in the Transactions
of the Royal Society*, it is asserted, that the white wood-stones
are generally found in the ground ; at from about two to six
miles distance from the lake, and sometimes very deep in the earth.

*Vol. xliv. No. 481.

60

The black ones are always found in the water, or on the shores of
the lough: sometimes in the mouths, or on the shores of rivulets,
that empty themselves into it. Those which have- wood continu-
ous with them, have not yet been found above twenty yards distance
from the waters of the lake ; which is about the distance to which
the waters reach in winter, and at other times., when its waters are
extraordinarily swelled. This gentleman observes, that the whet-
stones or hones, vulgarly so called, which are often sold for Lough
Neagh stones, are not so ; but are of a soft gritty kind, and are
found near Drogheda.

There seems, however, little reason to believe, that the waters of
Lough Neagh possess, at present, any petrifying power ; since
the supporters of .this opinion, have not been able to adduce a sin-
gle well supported fact in proof of it.

Mr. Carew observes, that " the Cornish tynners hold a strong
imagination, that in the withdrawing of Noah's floud to the sea, the
same took his course from east to west, violently breaking up, and
forcibly carrying with it the earth, trees, and rocks, which lay any
thing loosely, neare the upper face of the ground. To confirme the
likelihood of which supposed truth, they doe many times digge up
whole and huge timber trees, which they conceive at that deluge to
have been overturned and overwhelmed : but whether then, or
sithence, probable it is, that some such cause produced this effect*/'

He also observes, that " the ancient name of St. Michael's
Mount, was Car a Clowse in Cowse, in English, the hoare rock in the
wood : which now is, at every flood, encompassed by the sea, and
yet at some low ebbes, roots of mighty trees, are discryed in the
sands about it-f "

Camden not only notices those roots of mighty trees being seen
in the sands ; but remarks, that similar roots have been seen about

*The Survey of Cornwall, written by Richard Carew, Esq. 1602, p. 7.
t Ibidem, p. 3.

61

Plymouth Haven, and other adjoining places. This learned anti-
quary has enumerated many parts of England, where subterranean
trees have been discovered.

Childrey relates, that about two miles eastward from St. Mi-
chael's Mount, *at low water, they cast aside the sand on the shore,
and dig up turfs that are full of the roots of trees ; and on some
of these they have found nuts *. The tinners, he also says, do
many times dig up whole and huge timber trees, which they think
were overthrown, and have lain buried in the earth ever since the
flood f.

Childrey also states, that in divers places, in the low grounds
and champaign fields of the island of Anglesey, the inhabitants do
every day find, and dig out of the earth the bodies of huge trees,
with their roots ; and fir trees of a wonderful bigness and length :
which trees, in the opinion of Hugh Lloyd, were such as were cut
down by the Romans in their time ; because Tacitus saith, the
Romans, when they had conquered this island, caused all their
woods to be cut down, and utterly destroyed J. But from this
opinion, as some are found with their roots on, Childrey, with pro-
priety, dissents. He remarks, that there are also, on the shores of
Cumberland, trees discovered by the winds at low water, which are
else covered over with sand. And it is reported, he says, by the
people dwelling thereabouts, that they dig up trees without boughs,
out of the ground in the mossy places of this shire ; and that, by the
direction of the dew in summer ; for they observe, that the dew
never stands upon that ground under which they lie §.

This author, I believe, on the authority of Giraldus Cambrensis,
states, that at the time when Henry II. made his abode in Ireland,
were extraordinary violent and lasting storms of wind and weather;
so that the sandy shore on the coast of this shire (Pembrokeshire)

* Britannia Baconica, by J. Childrey, 1661, p. 10. f Ibid. p. 6.
{ Ibid. p. 15. § Ibid. p. 111.

62

was laid bare to the very hard ground, which had Iain hid for man v
ages: and by further exposure, the people found great trunks of
trees, which when they had digged up, they were, apparently, lop-
ped, so that one might see the strokes of the axe upon them, as if they
had been given but the day before. The earth looked very black,
and the wood of these trunks was altogether like ebony. At the first
discovery made by these storms, the trees (we speak of) lay so thick,
that the whole shore seemed nothing but a lopped grove*.

At Charmouth, in Dorsetshire, is found a petrified wood, which
agrees, in many of its appearances, with the larger masses of that
of Lough Neagh ; particularly in the dark bluish grey stone, with
which it is sometimes invested, and in the softness which is some-
times discoverable in the wood thus inclosed.

Indeed there is hardly any part of Europe, in which subterranean
wood, is discovered more generally, than in England ; there scarcely
being a spot through the whole island, where, upon digging to any
considerable depth, vegetable remains are not found. Thus we
learn from Dr. Plott, that at Wattington Park, in Oxfordshire, at
the bottom of a pond, were found some tons of oak ; and a pit beino-
sunk 50 or 60 feet deep, many whole oaks were found, one of which
was upright; one was also perpendicular, but inverted. All of
them were dyed through, of a black hue, like ebony, but sound
enough, and fit for many uses. Hazel nuts, and a large stag's head
with the brow antlers, were also found here, the horn being as
sound as the beam itself, and not at all dyed. In the same spot,
two Roman urns were also found -f-.

Dr. Plott also describes a stone, found between Clifton and Nune-
ham Courtney, which, he says, represents a sound piece of ash : re-
taining the grain and colour so well and lively, that nobody, at sight,

* Britannia Baconica, p. 142.

t The Natural History of Oxfordshire, by Dr. Plott, p. 161, ,- <*

63

believes it to be other than a firm and solid piece of wood. With
this, he adds, I struck fire to light the candle whereby I write this*.
Dr. Plott takes notice, also, in his Natural History of Stafford-
shire, of similar roots and trunks of trees being found in Shibben

o

Pool, and at Lay ton, and in many other places in that county.

Dr. Stukeley -j~ relates, that at Aukborough, in the north-west angle
of Lincolnshire, they discover the subterraneous trees, lodged here
at the deluge, in great abundance, along the banks of all the three
rivers ; the wood is hard and black, and sinks like a stone.

There is a wonderful appearance in nature, he says, all over this
country, and which is common to all such like upon the globe, as far
as my informations reach ; that is, the infinite quantities of subterra-
nean trees, lying three or four feet deep ; of vast bulk and different
species, chiefly fir and oak, exceeding hard, heavy, and black.
Many times the branches, reach so near day, as to break their
ploughs. After quoting what Pausanias relates, that ebony bears
no leaves, nor fruit, nor has any stock exposed to the sun, Dr.
Stukeley says, I doubt not but our author speaks of subterranean
trees ; and that our people might put this timber to better use than
burning it.

Rowlands, whose observations have a strong claim to our atten-
tion, says, We have many strong inducements to affirm, that this
island (Anglesey) was never under any water, except that of the
flood; for, as on the one hand, we find no symptoms of such a sub-
mersion ; no indication of so long steeping under water; and as a ne-
cessary consequence of that, no marine remains, properly such, in-
terspersed in our inland soil ; so, on the other hand, we find, in many
places of it, some evidences of its having been land, before the de-
luge. We find great bulky trees buried in slutch and mud, which in

* The Natural History of Oxfordshire, by Dr. Plott, p. 35 and 63.
t Itinerarium Curiosum, Gul. Stukeley, M. D. 1724.

64

all likelihood the deluge laid along, and found growing on or near
the places where we now find them; and if they grew near the-
places where they are found, as there are many signs they did, then
there is no question but it was terra firma before that deluge*.

In the fenny tract, called the Isle of Axholme, lying partly in Lin-
colnshire, and partly in Yorkshire, and extending a considerable way,
are also found vast numbers of oak, fir, and other trees, lying some-
what above three feet in depth; and, near to them, their roots, which
do still stand, as they grew, in firm earth below the rnoorf . Mr.
Dugdal«, in his book of Draining the Fens in England, concludes the
cause thereof to have been " the muddiness of the constant tides,
which flowing up Humber into Trent, left, in time, so much filth, as
to obstruct the currents of Idle, Done, and other rivers, which thence
flowed back, and overwhelmed that flat country."

Dr. Richardson, speaking of subterranean trees dug up at Youle,
in Yorkshire, says :

" Some of these trees are so large, that they are used for timber
in building houses, which is said to be more durable than oak itself.
The country people hereabout call them fir-wood. The bate or
texture of this wood is the same with fir, easily splitting : if burnt
it sends out the same resinous smell, and it affords the same coal.
The branches do generally grow in circles, as the knots do yet tes-
tify : the knots do easily part from the rest of the wood, as is usual
in fir-wood. The straightness and length of these trees, are also a
presumption, that they must be such ; if one consider, that some of
these are nigh an hundred feet long ; and at the bottom, not much
above a foot in diameter. Their tops lay all one way, (viz.) with
the current of the water. There are also oaks found there, though
not in so great quantity. The vitriolic parts of the earth, in which
they have lain, hath given them a black tincture quite through :

* Mona Antiqua Restaurata, Henry Rowlands, sect. iii. p. 8,
t Philos. Transact, vol. viii. No. 69.

65

which, when wrought and polished fine, is not much inferior to
ebony. The tryers, who search in the soft and boggy ground for
iron, do affirm, that at three or four yards depth, they find stumps
of trees broken off ; some of which are two, or three, or four feet
from the ground, and exactly the same wood with the subterraneous
trees. — That these trees are natives of this place, and not brought
here by a foreign deluge, I presume, he says, is almost demonstra-
ble ; though now there are neither firs nor pines growing naturally
here, nor have been in the memory of any man ; neither does there
remain the tradition of any such. The place, where these trees are
found is a long flat, on the one side bounded by the raging river
Humber, which often breaks its banks. Nigh this place, the Dun
empties itself into the river Humber. It is about twelve miles
below York *."

The observations of Mr. De la Pryme, on the subterranean trees
of Hatfield Chase f, are exceedingly interesting: he relates, that
Hatfield Chase contains within its limits 180,000 acres of land, of
which about 90,000 were annually overflowed, until they were
drained, and regained, for the purposes of agriculture, by the inge-
nuity and perseverance of Sir Cornelius Vermuiden, a Dutchman.
In the whole, or most of this tract, even in the bottom of the river
of Ouse ; in the bottom of the adventitious soil of all Marshland ;
and round about by the skirts of the Lincolnshire woulds, unto
Gainsburg, Bautry, Doncaster, Bain, Snaith, and Holden, are found,
he says, infinite millions of the roots and bodies of trees of all big-
nesses, great and little, and of most of the sorts that this island
either formerly did, or that it at present does, produce, as pitch
trees, commonly called firs, oaks, birch, beech, yew, wirethorn,
willow, ash, &c. the roots of all, or, of most of which, stand in the
soil in their natural postures, as thick as ever they could grow,
most of them laying by their proper roots. Mostofthe great
* Philos. Transact, vol. xix. No. 28. t Phil. Trans, vol. xxii. p. 980.

VOL. 1. K

66

trees lay all their length, about a yard from their great roots (unto
which they did most evidently belong, both by their situation, and
the sameness of the wood) with their tops commonly north-east ;
though indeed the smaller trees lie almost every way across those,
some above, some under ; a third part of all which are pitch trees,
commonly called firs, some of which have been found of thirty yards
length and above, and have been sold to make masts and keels of
ships. Oaks have been found of twenty, thirty, and thirty-five
yards long, yet wanting many yards at the small end. Some of
which have been sold for four, eight, ten, and fifteen pounds apiece ;
which are as black as ebony, and very lasting and durable in any
service that they are put unto. As for ashes, it is commonly ob-
served of them, that their constituent parts are so dissolved, that
they become as soft as earth, and are commonly cut in pieces by
the workmen's spades ; and, as soon as flung up into the open air,
fall away into dust; but all the rest, even the willows themselves,
which are softer than ashes, preserve their substance and texture,
he says, to this day. He adds, I have seen some pitch or fir trees,
that, as they have laid all along, after that they were fallen, have
struck up great branches from their sides, which have grown unto
the thickness and height of considerable trees.

Many of those trees, he observes, of all sorts, have been burnt;
but especially the pitch or fir trees ; some quite through, and some
all on a side ; some have been found chopped and squared, some
bored through, other some half riven, with great wooden^vedges and
stones in them, and broken axe heads, somewhat like sacrificing
axes in shape : and all this in such places, and at such depths, as,
could never be opened from the destruction of this forest, until the
time of the drainage. Near a great rock, in the parish of Hatfield,
were found eight or nine coins, of some of the Roman emperors, but
exceedingly consumed and defaced with time. It is very observa-
ble, he adds, that upon the confines of this low country, between

6?

Birmingham and Brumley, in Lincolnshire, are several great hills of
loose sand, which, as they are yearly worn and blown away, there
are discovered under them many roots of great firs or pitch trees,
with the impresses of the axe as fresh upon them as if they had but
been cut down a few weeks, which I have several times, with plea-
sure, taken notice of, as I have rode that way.

Hazel nuts and acorns have frequently been found, at the bottom
of the soil of those levels and moors ; and fir or pitch tree apples, or
cones, in great quantities, by whole bushels together. And at the
very bottom of a new river or drain, that the drainers cut, (almost
100 yards wide, and four or five miles long) were found old trees,
squared and cut, rails, stoups, bars, old links of chains, horses' heads,
an old axe somewhat like a battle-axe, with two or three coins of the
Emperor Vespasian : but that which is more observable, is, that the
very ground, at the bottom of the river, was found, in some places,
to lie in rigg and fur, manifesting thereby, that it had been tilled
and ploughed in former days.

From an oak tree having been found in these moors forty yards
long, four yards diametrically thick at the great end, three yards
and a foot in the middle, and two yards over at the small end ; and
which, by moderate computation, appeared to have been as long
again: and from a pitch or fir tree having been found thirty-six yards
long, the computed length of which might be fifteen yards more, he
observes, there is reason to suppose, that the trees of these levels
must have ^een exceeding great.

The Rev. W. Derham relates, that many subterraneous trees were
laid bare by a breach in the Thames wall ; when, by the violence of
the water, a passage was torn up, an hundred yards wide, and twenty
feet deep. Mr. Derham says, we discover these trees all along the
Thames side, over against Rainham, Wennington, Purfleet, and other
places. The trees appeared to be chiefly alder or hornbeam, both of
which blacken in a solution of copperas*.

* Philos, Transact. No. 325.

The Rev. W. Borlase relates, that great numbers of subterranean
trees were found on the shore at Mount's Bay, Cornwall. These tree*
were very large, and appeared to be oaks, hazel, and willow trees
they were found three hundred yards below full sea mark ; and when
the tide is in, have at least twelve feet of water above them. This,
he thinks, confirms the tradition, already noticed, that St Michael's
Mount, now half a mile inclosed with the sea, when the tide is in,
stood formerly in a wood*.

Sir John Hill states, that he often met with pieces of wood, very
little altered from their original state, in strata of loam among gra-
ve}; and even in solid beds of stone, particularly at the great quar-
ry^ at Mr. Allen's, near Bath, in which he saw part of an elm, of
more than four feet in length, which was still soft enough to be*
easily pierced with a knife -f.

When the mind is engaged in the consideration of a subject, so
interesting as that to which I am endeavouring to attract your at
tention ; it is highly gratifying to find, that necessary investigations
have been made by men, whose learning and abilities have engaged
our respect. The following observations, independent of the im-
portance they derive from their authors, are in themselves so highly
interesting, that no apology can be necessary for laying them be-
fore you, almost unaltered in their form.

In September, 1796, the Right Honourable the President of
the Royal Society, accompanied by Dr. Joseph Correa de Serra,
went to Sutton, in Lincolnshire, to examine the nature and ex-
tent of certain islets of moor, chiefly composed of decayed trees,
situated along that coast, and visible only in the lowest ebbs of the
year.

These islets, according to the most accurate information, extend
at least twelve miles in length, and about a mile in breadth, oppo-
site to Sutton Shore ; and consist almost entirely of roots, trunks,
branches, and leaves of trees and shrubs, intermixed with some

* Philos. Transact, vol. i. part 1. t Natural History of Fossils, p. 638.

leaves of aquatic plants. The remains of some of these trees were
still standing on their roots, while the trunks of the great part lay
scattered on the ground, in every possible direction. The barks of
trees and roots appeared, generally, as fresh as when they were
growing; in that of the branches particularly, of which a great
quantity was found, even the thin silver membranes of the outer
skin were discernible. The timber of all kinds, on the contrary,
was decomposed, and soft in the greatest part of the trees : in some,
however, it was firm, especially in the roots. The people of the
country have often found among them very sound pieces of tim-
ber, fit to be employed for several economical purposes.

The sorts of wood, which are still distinguishable, are birch, fir,
and oak. Other woods evidently exist in these islets, of some of
which the leaves were found in the soil. In general, the trunks,
branches, and roots of the decayed trees were considerably flat-
tened ; similar to the surturbrand or fossil wood of Iceland, as well
as to that found in the lake of Thun, in Switzerland.

The soil to which the trees are affixed, and in which they grew,
is a soft greasy clay ; but for many inches above its surface, the soil
is entirely composed of rotten leaves, scarcely distinguishable to
the eye ; many of which may be separated by putting the soil in
water, and dexterously and patiently using a blunt spatula or knife.
By this method the Doctor, from whose account this extract is
made, obtained some perfect leaves of ilex aquafolium, which are
now in the herbarium of the Right Honourable Sir Joseph Banks ;
and some other leaves, which, though less perfect, seem to belong
to some species of willow. In this stratum of rotten leaves, could
also be distinguished some roots of arundo phragmites.

By examining a well, dug at Sutton, by Joshua Searby, these
gentlemen discovered, that a moor of the same nature is found un-
der ground in that part of the country, at the depth of sixteen feet ;
consequently very nearly on the same level with that which consti-

70

lutes the islets. The disposition of the strata, was found to be
nearly as follows :

Clay 16 feet

Moor, similar to that of the islets ... 3 to 4 feet
Soft moor, like the scouring of a ditch bot-
tom, mixed with shells and silt 20 feet

Marly clay 1 foot

Chalky rock from i to 2 feet

Clay . . . • 31 yards

Gravel and Water ; the water having a chalybeate taste.

In order to ascertain the course of this subterraneous stratum of
decayed vegetables, Sir Joseph Banks directed a boring to be made,
in the fields belonging to the Royal Society, in the parish of Mable-
thorpe. Moor, of a similar nature to that of Searby 's well, and the
islets, was found, very nearly on the same level, about four feet
thick and under a soft clay.

The whole appearance of the rotten vegetables which were found,
perfectly resemble, according to the remark of Sir Joseph Banks,
the moor which in Blankeney Fen, and in other parts of the East
Fen, in Lincolnshire, is thrown up in the making of banks ; barks,
like those of the birch tree, being there also abundantly found. The
moor extends over all the Lincolnshire fens, and has been traced
as far as Peterborough, more than sixty miles to the south of Sutton.
On the south side, the moory islets, according to the fishermen,
extend as far as Grimsby, situated on the south side of the H um-
ber ; and it is a remarkable circumstance, that in the large tracts of
low land, which lie on the south _banks of that river, a little above
its mouth, there is a subterraneous stratum of decayed trees and
shrubs, exactly like those observed at Sutton ; particularly that of
Axholme Isle, and that of Flatfield Chace, which have been already
described.

71

Little doubt can be entertained, of the moory islets of Sutton
being a part of this extensive and subterraneous stratum, which, by
some inroad of the sea, has, in that part, been stripped of its cover-
ing of soil. Sufficient reasons for this opinion, the Doctor thinks,
are yielded by the identity of the levels, as well as that of the species
of trees; the roots of these being affixed, in both, as to the soil
where they grew; and, above all, the flattened shape of the trunks,
branches, and roots, found in the islets, which can only be accounted
for by the heavy pressure of a superinduced stratum. Such a
wide spread assemblage of vegetable ruins, lying almost in the
same level; and that level generally under the common mark of
low-water, must naturally strike the observer, and give birth to the
following questions : — 1. What is the epoch of this destruction ?
2. By what agency was it effected ?

Whilst endeavouring to answer these questions, the learned writer
supposes, the fossil remains of vegetables, hitherto dug up in so
many parts of the globe, to belong to two different states of our
planet. The parts of vegetation, and their impressions, found in
mountains of cetaceous, schistous, or even sometimes of a calcare-
ous nature, are chiefly of plants now existing between the tropics ;
which could neither have grown in the latitudes, in which they are
dug up ; nor have been carried and deposited there by any of the
acting forces, under the present constitution of nature. The forma-
tion, indeed, he justly remarks, of the very mountains in which they
are buried ; and the nature and disposition of the materials which
compose them, are such as we cannot account for by any actions,
and reactions, which in the actual state of things, take place on the
surface of the earth.

The consideration of this order of fossil vegetables obliges us, in
the opinion of Dr. de Serra, to recur to that period in the his-
tory of our planet, when the surface of the ocean was at least so

72

much above its present level, as to cover even the summits of those
secondary mountains which contain the remains of tropical plants.
But whether we suppose these plants to have grown near the spot
where they are found, or to have been carried thither, from different
parts, by the force of an impelling flood, it is equally difficult, he
remarks, to conceive, how organized beings, which, in order to live,
require such a vast difference in temperature and in seasons,
could live on the same spot : or how their remains could (from cli-
mates so widely distant) be brought together in the same place, by
one common dislocating cause. To this ancient order of fossil ve-
getables belong whatever retains a vegetable shape, found in or
near coal mines, and (to judge from the places where they have
been found) the greater part of the agatized woods.

The second order of fossil vegetables, comprehends those which
are found in the strata of clay and sand ; materials which are the re-
sult of slow depositions of the sea, and of rivers ; agents still at work,
under the present constitution of our planet. These vegetable re-
mains are found, in such flat countries as may be considered to be
of a new formation. The vegetable organization still subsists, at
least, in part ; and this vegetable substance has suffered a change
only in colour, smell, or consistence; alterations which are pror
duced by the developement of their oily and bituminous parts, or
by their natural progress towards rottenness. To this description
of fossil vegetables, the decayed trees, and other vegetable remains,
belong, which constitute the greater part of the mass of which this
moor is formed. Although these trees are standing in their native
soil, Dr. deSerra reminds us, that the level in which they are found
cannot be the same as that in which they grew ; and we should there-
fore, conclude, that the forest here, described, grew in a level high
enough to permit its vegetation, whiqh could not have been the
case if it had been so near the sea,, qr bejtow, the c(pmmon level of

its water. He attributes this change of situation to the force of re-
sidence ; but as the effect here produced, appears to be too great to
have been affected by the natural consequence of gravity, slowly,
though perpetually, operating, he rather attributes it to the force of
subsidence, suddenly acting by means of some earthquake. The
stratum of soil, sixteen feet thick, placed above the decayed trees,
seems to remove the epoch of their sinking and destruction, far be-
yond the reach of any historical knowledge.

From the exact resemblance, between maritime Flanders and the
opposite coast of England, in point of elevation; as well as in the
structure and arrangement of the soils, he infers, that the countries
are certainly coeval : and concludes, that whatever proves that ma-
ritime Flanders has been for many ages out of the sea, must also
prove that the forest, here spoken of, must have been, long before
that time destroyed, and buried under a stratum of soil. But al-
though he supposes the original catastrophe, which buried this fo-
rest, to be of very ancient date, he suspects the inroad of the sea,
which uncovered the decayed trees of the islands of Sutton, to be
comparatively recent: and to have been produced by some of the
stormy inundations of the North Sea, which, in these last centuries,
have washed away such large tracts of land on its shores ; taking
away a soil resting on clay, and thereby uncovering a part of this
subterranean forest*.

In the gravel pits, near the tile kiln in Hackney road, belonging
to Mr, William Rhodes, parts of trees have been found, buried at
various depths. I have repeatedly found mineralized wood in this
spot, in the dark blue clay, which is dug for the purpose of tile
making, and at the depth of twenty-one feet.

Wishing to impress on your mind the existence of subterranean
and mineralized woods in almost every known part of this globe, I

* Philosophical Transactions for 1799.
VOL. I. L

74

must again repair with you to distant parts, to shew you, that
wherever attentive observations have been made, proofs of this fact-
have been found.

Thus Mons. de la Hire gives a particular description of part of
the petrified trunk of a palm tree, which he had obtained from
some part of Africa.

The petrified trunk of a palm tree was also found in the desert
near the isthmus of Suez, and transmitted to the class of natural
history by General Regnier, member of the institute of Egypt.

In the account of Mr. Horneman's travels, in the years 1797 and
1798, undertaken for the purpose of exploring the interior parts of
Africa, we learn, that in that vast desert which forms the natural
boundary of Egypt, petrified wood is found, of various forms and
size. Sometimes are seen whole trunks of trees, of twelve feet cir-
cumference, or more ; sometimes only branches of twigs, scarcely
of a quarter 6f an inch diameter ; and sometimes merely pieces of
bark, of various kinds, and? in particular, of the oak, are to be
found. Many of the great stems yet retain their side branches, and
in many the natural timber has undergone so little change, that the
circular ranges of the wood are discernible, and especially in those
trunks which were apparently of oak. The interior of other bodies
of timber are said to have become a petrifaction, shewing no dis-
tinctions of grain or fibre, but bearing the appearance of mere stone ;
though the outward coat and form of the substance clearly denoted
the tree.

Mr. Horneman was informed by several Arabs, that in travelling
over this desert, petrified trees were often found upright, and as if
growing in the soil ; but he presumed, respecting those he did not
see, from those he did actually inspect, that they were trunks raised
by hand, round the base of which the sand had quickly gathered
before the winds, and formed a mound, as if heaved up by a root.
The colour of the petrified wood is in general black, or nearly so ;

75

but, in some instances, it is of a light grey, and then so much re-
sembles wood in its natural state, that the slaves would often collect
and bring it in for the purposes of firing.

These petrifactions are, sometimes, scattered in single pieces ;
but are oftener found in irregular layers, or strata, covering, toge-
ther, a considerable space of ground*.

Yours, &c.

LETTER VIII.

CONSTITUENTS OF VEGETABLES.. ..FOOD OF VEGETABLES.

HAVING, in my former letters, pointed out some of the numerous
places, in different parts of the earth, where fossil vegetables have
been found; and having thereby enabled you to judge, how very
generally they are diffused, beneath the surface of the earth, I shall
now endeavour to describe the various states into which vegetable
matter is reduced, after ceasing to perform the functions of vege-
table life.

As in doing this, I am aware that I shall be under the necessity
of disposing, amongst altered vegetable matter, some substances,
which those, whom I, and every other student in chemistry and ge-
ology, must regard as high and respectable authorities, have denied
the propriety of thus classing, such an arrangement shall be
adopted, as appears to be best calculated to place the opinions I

* The Journal of Frederic Horneman's Travels from Cairo to Mourzouk, the capi-
tal of the kingdom of Fezzan, in Africa, in the years 1797-8.

76

offer in the fairest point of view. I shall, therefore, in the first
place, describe these substances, and particularize the circumstances
attendant on their discovery, and then shall endeavour to point out
the nature of these various modifications of vegetable matter, and
the different processes on which they depend.

But, previously to entering into a particular examination of the
changes which take place in vegetables, in the several processes to
which they are subjected, whilst passing into a state of mineraliza-
tion; it is necessary to give some slight account of the substances
of which they are composed, during their vegetable state ; and of
such chemical changes as appear to be subservient to the offices of
vegetation.

Vegetables, besides containing oils, acids, alkalies, earths, and
metals, in common with substances of the animal and mineral king-
doms, do also contain the following substances, which are peculiar
to the subjects of the vegetable kingdom : — Starch, gum, sugar,
extract, tannin, wax, resins, camphor, caoutchouc, wood, cork.
The analysis of these substances manifest, that oxygen, carbon, and
hydrogen, entering into a triple combination, constitute, with some
of the earths, the greatest part of their mass. In several of these
substances, nitrogen is also found to exist ; and in some, sulphur
has been found. Phosphates of lime, &c. have likewise been
found in the analysis of some vegetables: the phosphoric acid
having been, probably, derived from the phosphorus yielded by the
decomposition of animal matters, in the soil in which these vegeta-
bles grew.

Water was once supposed to be the chief, if not the sole, food of
plants. This opinion has been long doubted; but the ingenious
experiments of Hassenfratz have furnished us with additional means
of solving this interesting question. It appears, that the water does
not add to the stock of carbon, so necessary to the growth of the
plants but only serves for the diffusion of that which the bulb origi-

77

nally contained : water, therefore, cannot be considered as the sole
food of plants.

If water does not constitute, alone, the food of plants, it is, how-
ever, absolutely necessary to their existence ; serving as the vehicle,
by which those substances, from which they derive a larger portion
of nutriment, are conveyed through their system of vessels. Water
is also, most probably, so acted on in the vegetable system, that it
is resolved into its two simple principles, hydrogen and oxygen:
both of which are well known to exist, in almost every vegetable
substance ; and are presumed to be absolutely necessary to the
performance of various important functions, in the vegetable
oeconomy.

In all vegetables is discovered, by analysis, a considerable por-
tion of carbon ; particularly in those, in which the woody fibre is
most abundant : thus, in trees, it constitutes, upon an average,
nearly a fifth of their whole substance. Analysis has also mani-
fested, that the water which drains from a dung-hill, and all fertile
soils, contain a very large proportion of carbonaceous matter. That
carbon, therefore, is a food of plants, appears to be established
almost beyond a doubt.

How indispensible to vegetation are the various combinations of
earths, must be evident to every one. They form a proper medium,
by which the due quantity of water is regularly diffused, and ad-
ministered, to the various plants which the ground bears. They
also form a mass sufficiently yielding to allow the ready extensions
of the roots of plants, in every direction ; at the same time pos-
sessing sufficient tenacity and firmness, to secure them stability
in their situation.

But chemical analysis has demonstrated, that all* plants contain
more or less of earth in their composition. Saussure, jun. planted se-
veral trees in a granitic, and in a calcareous soil : and after analysing
the soil, analysed the trees ; when he found, that the trees which

78

had grown in the granitic soil, contained most water ; but that the
proportion of charcoal was nearly alike in those of each soil. The
quantity, however, and proportion of the earths which he found
they contained, corresponded, very nearly, with the contents of the
respective soils ; thus the trees which grew in the granitic soil,
abounded in silica, and contained metallic oxides ; whilst those
which grew in the calcareous soil, contained no metallic oxide, but
a considerable proportion of lime. This, however, will appear
more obvious by the following tabular representation of the results
of his experiments, made with the pinus abies.

Analysis demonstrated the contents of the two soils and the con-
stituent parts of the pinus abies, in the different soils to be as
follows :

Analysis of the Granitic Soil.

73,25 Silica
13,25 Alumine

1,74 Lime

9,00 Iron and manganese

97,24

Analysis of the Calcareous Soil.

98,000 Carbonate of lime
0,625 Alumine
0,625 Oxide of iron
O,02 5 Petroleum

99,275

Analysis of the Fixed Substances contain-
ed in the Pinus Abies, growing in the
Granitic Soil.

13,49 Silica

14,86 Alumine

46,34 Carbonate of lime

10,52 Metallic oxides
3,60 Pot-ash

4,24 Alkaline sulphates and muriates
0,77 Carbonate of magnesia

99,82

Of the Fixed Substances , containedinthe Pi-
nus Abies growing in the Calcareous Soil.

63 Carbonate of lime
16 Alumine

15 Alkalies and alkaline sulphates
and muriates

94

The absorption of earths, metallic oxides, and various saline sub-
stances, for the accomplishment of important purposes, in the vege-

79

table oeconomy, cannot therefore be in the least doubted. Nor
can there exist the least impropriety, in considering these sub-
stances, as well as phosphorus and sulphur, when thus imbibed, as
constituting a part of the actual food of plants.

The subject of the present letter may have been unexpected ;
but be assured, it was necessary to be discussed, before we could
enter more fully into the peculiar object of our enquiry. A very
little consideration will shew you, that we should be able to make
but a trifling progress in an examination into the subsequent
changes which these bodies undergo; unless we had first ascer-
tained the substances which had entered into their original compo-
sition.

Yours, &c.

LETTER IX.

RESOLUTION OF VEGETABLES INTO THEIR FIRST PRINCIPLES....
PIRST STEP IN THE MINERALIZATION OF VEGETABLES... .VE-
GETABLE MOULD.. ..IGNIS FATUUS.

1 N tracing the transition of vegetable matter, into a mineral state,
it is proper to commence our remarks by an examination of the
changes which plants undergo, immediately on the extinction of
vegetable life.

When from accident, or in consequence of the attainment of the
full period of maturity, a tree or a forest falls, a resolution of

80

composition necessarily succeeds : the constituent parts separate,
and the elementary, or simple principles, disengaged from those
connections into which they had been forced by the energies of ve-
getable life, now enter into new combinations, resulting, almost,
from chemical attractions merely.

The epidermis, as well as the parenchyma of the leaves, and the
other succulent parts, soon become resolved into a soft mass, which
yields an unpleasant odour, and which acquires much of its moisture
from the extravasation of the sap and other vegetable juices. The
mass derives, perhaps also an increase of its fluidity, from the hydro-
gen and oxygen, which had been employed in the. formation of vari-
ous parts of the vegetable, being now let loose, and entering into a
new combination, by which water is formed. Another portion of the
hydrogen becomes also volatilized, and uniting with a portion of car-
bon, forms carburetted hydrogen gas, and other inflammable gases,
somewhat similar in their composition. In the decomposition of
those plants, into the composition of which nitrogen enters, this
principle enters directly into union with the hydrogen, at the mo-
ment of their liberation, forming the volatile alkali ; the odour of
which is sometimes perceptible. The carbon, or coaly matter, is
partly employed, though but to a small extent, in the combinations,
with the hydrogen gas, just mentioned ; whilst another small por-
tion combines with the oxygen gas, and is liberated in the form of
carbonic acid gas. The oxygen is chiefly disposed of in the combi-
nations already described. Some of this principle, however, as well
as a portion of the hydrogen and of the nitrogen also, if present, as-
sumes the concrete state, and becomes involved with a very consi-
derable portion of the carbon, in the magma, from which the
gaseous and the more volatile parts have escaped.

After this mass has been exposed to the atmosphere for some
time, and the evaporation of its more humid parts has taken place,
a small portion of soft, dark brown, or black, pulverulent matter is

81

left ; containing the earths and other solid matters, which preceding
vegetation had subtracted from the earth's surface. This sub-

^

stance, which is termed humus, or virgin mould f when mixed with
clay, sandy loam, and other particles of different earths, forms the
general crust of the dry and habitable part of this globe. Con-
taining so many of the principles which are requisite to the forma-
tion of vegetable matter, and greedily attractive from the super-
ambient air, of oxygen, the dissolvent principle of the various sub-
stances absorbed by vegetables, it may be considered as the grand
reservoir of the food of plants. Its soft and yielding nature, ren-
ders it, at the same time, a matrix fitted to promote the process of
germination, and for the free diffusion and divarication of the ten-
der radicles of the infant plant.

The formation of mould is, doubtless, one species, or rather
mode of mineralization of vegetable matters, and therefore claims
the attention it has here received : but as the substance thus pro-
duced never bears the form of any of the organized substances, from
which it has derived its existence, we need dwell no further on it,
except to notice two curious and interesting phenomena, which it
sometimes offers to our observation.

The first of the phenomena, here meant, is that which is termed
the Ignis fatuus, or Will of the Wisp. This is well known to be a
lambent flame, appearing at night, over marshy lands ; and which,
by its flitting motion, and by the sudden dissappearance, and as
sudden renewal of its flame, serves frequently to mislead the wan-
dering, and even cautious traveller.

Dr. Shaw has furnished us with the following curious account of
the phenomena yielded by this extraordinary meteor, of which he
was enabled to obtain the closest inspection: He says, that in
travelling by night, in the beginning of April, through the valleys of
Mount Ephraim, we were attended, for the space of an hour, with
an Ignis fatuus, that displayed itself in a variety of extraordinary

VOL. i. M

82

- appearances. For, it was sometimes globular, or else pointed like
the flame of a candle ; afterwards it would spread itself, and involve
our whole company in its pale and inoffensive light; then at once
contract, and suddenly disappear. But in less than a minute, it
would begin again to exert itself as at other times; running along
from one place to another, with great swiftness, like a train of gun-
powder, set on fire ; or else it would spread and expand itself over
more than two or three acres of the adjacent mountains; discover-
ing every shrub and tree that grew upon them. The atmosphere
from the beginning of the evening, had been remarkably thick and
hazy ; and the dew, as we felt it upon our bridles, was unusually
clammy and unctuous*.

The late discoveries in chemistry, give us reason to hope, that
an explication of this extraordinary appearance may, before long.
be obtained. It is generally attributed to some inexplicable agency
of the electric fluid on the inflammable air of marshes ; but it seems
rather to depend on some hitherto unknown combination of phos-
phorus, with carbon or sulphur, in hydrogen gas, separated from
the wetted vegetable mould.

It is true, that on phosphuretted hydrogen gas coming in contact
with the atmosphere, actual inflammation takes place ; whereas in
ignes fatui the illumination appears to be that of phosphorescent
light only ; but that the subsequent industry of chemists will
enable them to imitate this phenomenon still more closely, seems
very probable. Indeed, there seems to be reason for expectation,
that such a result may be the reward of a careful series of experi-
ments, in which the phosphorus is combined, in different doses,
with other gases, containing various proportions of the several sim-
ple combustible bodies — perhaps the gaseous oxide of carbon might
be found well calculated to repress the combustion, whilst it per-

* Travels, or Observations relating to several parts of Barbary, and the Levant, by
Thomas Shaw, D.D. F.R. S. 2d edition, 1756, p. 334,

^ 83

mitted the emission of the phosphoric light. The volatile alkali,
also in such experiments, might become a useful agent ; since, in
the distillation of the salt, formed by the union of this alkali, with
phosphoric acid, a gas comes over, which does not instantaneously
inflame, but displays a phosphoric light, when it comes in contact
with oxygen gas.

The other phenomenon, which is yielded by the mould formed of
the mineralized remains of vegetables, is a corruscating light, pro-
duced by its percussion under certain circumstances. This pheno-
menon has been seen by Dr. Plott and others. Dr. Plott's account
of it is as follows : —

" Under the uppermost turf, in their moorish boggy grounds,
they also dig peats, which, because they order much after the same
manner, as has already been described in Oxfordshire, I pass them
over, and proceed to another black, moist, and rotten sort of earth,
that lies just under the turf, in heathy soils, such as Archer Moore,
near Berresford, and upon a hill called the Gun, above Rudyerd
Hall, where, as I was seriously told by the worshipful and most in-
genious Charles Cotton, Esq. Thomas Rudyerd, of Rudyerd, Esq.
and Mr. Gent, of Asbourn, if one ride in a dark night in so wet a
season, that a horse breaks through the turf, and throws up this
black, moist, spongy sort of earth, he seems to fling up so much fire,
which lies shining upon the ground like so many embers ; by the
light whereof one horse may trace another, though at some dis-
tance, and it be never so dark ; it continuing light upon the ground,
and being gradually dying away, for near a quarter of an hour. To
which let me add another agreeable relation, whereof I was inform-
ed by that worthy loyal gentleman Capt. Thomas Lane, of Bentley,
who, endeavouring to help a friend and kinsman (one Mr. Jones),
who casually fell in a ditch, in Bescott grounds, in the night time,
and having stirred the mud and dirt pretty much in perform-
ing that good office ; they presently found their gloves, bridles, and

84

horses, as far as the water or dirt had touched them, all in a kind
of faint flame, much like that, as he described it, of burnt brandy,
which continued upon them for a mile's riding*/'

The foregoing account, exactly agrees with a curious history of
the same phenomenon, contained in the collection of manuscript
communications, to the Royal Society, in the library of the British
Museum. It is entitled, " A Relation of a fiery Appearance in the
Impress of Mens' and Horses' Feet," and was given in these words,
by Dr. Croon, about the year 1665 :

" Being Monday, on my return with Sir John Courton, bait, and
his clerk, William Stephens, from the Lord Bishop's visitation at
Launceston, about an hour, in a misty dewy night, on Hinxon,
about a mile beyond Kellington, in Devonshire, in Launceston
road, in a moorish place of some forty feet in length, the impress of
our horses and our own feet upon the ground, appeared fiery, much
more shining than glow-worms ; the grass we gathered in those
places where we or our horses trod, reserved the lustre in our hands
when we came to the waters within a quarter of a mile from Kel-
lington ; where watering our horses, we observed it, but almost ex-
tinguished only a spark here and there. At Newton, two miles
thence, we viewed it by candle-light that night, as also the next
day, and found it coarse spiry grass, of an inch, or little more, in
length, such as ordinarily grows on downsf.

That this phenomenon, as well as that of the Ignis fatuus, depends
on some peculiar modification of phosphorus, there seems to be no
difficulty of admitting. Nor can there exist any doubt, as to the
source whence volatile alkali, and even the phosphorus itself, is de-
rived, when it is recollected, that, with this crust of mould, a consi-
derable quantity of animal matter must be blended, proceeding from
the myriads of insects which had fed on the vegetables. From the

* The Natural History of Staffordshire, by Dr. Plott, p. 115.
t Mr. Ayscough's Catalogue, 698, p, 47,

85

resolution of animal and even vegetable matter, in subterranean
situations, may also have proceeded the various metallic and other
phosphates, so eminent in their brilliance an4 colours.

Yours, &c.

LETTER X.

PEAT OR TURF.. ..DESCRIPTION OF.... VARIOUS KINDS. ...LENGTH OF
TIME KNOWN.. ..FOUND IN VARIOUS PARTS OF THE WORLD.

THE substance, to which I next wish particularly to attract your
attention, is one which has been seldom considered in relation to
the bodies termed petrifactions ; but which I suspect, is very nearly
connected with those which derive their origin from the vegetable
kingdom. Indeed, I shall endeavour to prove to you, that most
of these bodies which have obtained so considerable an alienation
from their original nature, have first passed through an intermediate
state ; resembling that, in which the substance which is the subject
of our immediate inquiry, is always found to exist.

The substance here alluded to, is peat or turf; well known to the
inhabitants of most lowland countries, for the advantages it affords
them by its combustible quality. It is found in various parts of the
world, forming immense tracks, at various depths. It is a soft but
compact substance ; its colour being of a bright reddish brown. As it
dries, upon exposure to the air, it becomes soon darker ; the dark-

86

ness increasing, in the best peat, until it acquires almost the black-
ness of coal : at the same time it becomes a hard, tough, weighty
mass, very difficult to be cut or even broken ; and which, in general,
contains many remains of vegetable matter. It absorbs water, and
retains it so strongly, as to be found almost always in a wet state,
in its natural situation ; hence, when near the surface, it forms bogs,
which are exceedingly dangerous to such animals as attempt to pass
over them. The best peat is smooth, and cuts clean with the peat-
spade, being almost of the consistence of soap.

Like clay that has been burned, peat, on being dried, loses the
property of forming a tenacious mass, by the addition of water.
When properly dried, which is accomplished, by cutting it into
square pieces of the size of a brick, and exposing it to the conjoint
action of the sun and air, the peat becomes a very combustible sub-
stance ; burning, when pure, with a clear bright flame, and yeild-
ing a hard firm charcoal, which burns with a vivid glow, until re-
duced to a very small portion of very light and white ash. Some-
times it contains small branches and twigs, in which the woody
fibres still possess so much of their original state, as to give consi-
derable resistance to the peat-spade. Oftentimes it appears to be a
composition of the roots, branches, twigs, and leaves of trees, various
parts of plants, grass, straw, &c. but little altered in their form, al-
though in their nature, they are now rendered entirely different

The varieties here enumerated, appear to be the consequences of
different degrees of perfection, to which the natural process, to
which these substances have been exposed, has proceeded. But it
is not the smaller and the less hard parts of vegetables only, which
are thus found imbedded ; since, frequently, large trees are found in
different parts of the peat, increasing the expense and adding to
the trouble of the peat-digger, by the obstacles they yield to his
operations.

Other varieties, in its appearance, are frequently observable ; de~

87

pending on the quantity of the extraneous matters, with which it
has become blended. When its purity is much impaired, it is found
to burn with considerable less freedom ; and a close inspection will
shew, by its being not smooth in its cut, but gritty in its substance,
that its impurity proceeds from an intermixture of earth. If the
peat be good, and contain but few impurities, it burns with a clear
bright flame, leaving ashes of a light colour ; but if much earth is
blended with it, the ashes are more plentiful, and, from the igni-
tion having been thereby impeded, are of a darker colour. If, as
is frequently the case, it contains much pyrites, or ferruginous earth,
then a heavy reddish ash is left.

Adrianus Junius observes, that there are several kinds of these
turf-like substances. The first kind, which he describes, is of a red-
dish colour, poor, and spongy ; very light, and of but little value ;
being only used to heat brewers' coppers. Whilst burning, it gives
to the countenance a livid, cadaverous hue ; making men appear
like ghosts : it, at the same time, produces a noxious vapour, which
occasions fainting ; to prevent which it is sprinkled with salt. The
second kind is more dense, of a blackish brown colour, and is inter-
sected by twigs and rushes, in various directions. It is heavier
than the former kind, and more generally useful. The third kind
is heavy, and sinks in water, which the former kinds do not. It is
of an ash colour, and is dug in a sandy soil : it takes fire slowly, but
continues to burn a long time. He observes, that there is another
kind, formed of the salt earth in Zealand ; and besides these, he re-
marks, there is another kind, which is obtained from the fatty mud,
which is dragged from the bottom of ponds, and is afterwards
drained, and so dried by exposure to the air, as to render it use-
ful*. Schoock remarks, that the peat, which is dug from the

* Historia Bataviae, cap. v.

88

deeper parts of the earth, is more firm, and is of much higher esti-
mation, than that which is found nearer the surface.

The peat is, sometimes, found even near the surface, under
a slight covering of mould, formed by the more recent decompo-
sition of vegetable matter. Sometimes this surface is tolerably
well stocked with heath and other vegetables ; but more frequently
it presents to the eye an extensive barren flat moor, which, ex-
cept in the driest seasons, is so wet and spongy, as to be entirely
impassable.

According to Dr. Anderson, well known for his vigilant atten-
tion to those circumstances, on which the comforts of humble life
depend, it is found at various depths, under strata differing very con-
siderably in their composition, thickness, and number.

Peat, as Mr. Jameson observes, is most commonly to be found in
valleys and plains, where it forms very extensive beds ; varying in
their depth, from one foot to full forty feet. Sometimes it is dis-
covered at the sides of mountains; but even there its beds preserve
an horizontal situation. Mountains, upwards of two thousand feet
high, in the Highlands of Scotland, have their tops covered with peat
of an excellent kind. In Germany, it is also found at very great
heights; thus the Blogsberg, a high mountain in Lower Saxony,
and the Brohen, the highest mountain of the Hartz, are covered to
their summit with peat. It is also found at the bottom of ponds
and canals ; and is sometimes brought up on the coast of Holland,
by the flukes of anchors ; and also cast on shore in stormy weather,
which has induced some to imagine it to be of marine origin. In the
harbour of Oban, in Argyleshire, one part of the bottom appears
to be formed of quick moss, which affords no sure anchorage. The
depth of the sea is there about twenty fathoms.

In Galloway is the great moss of Cree, lying near to the sea, a
little higher than flood-mark at spring tides. Near Dumfries is
Locker Moss, only a few feet above high water mark ; it is about

89

ten miles in length. In the island of Lewis, one of the Hebrides,
there is an extensive peat moss, thirty miles long, having its surface
but little elevated above that of the sea*.

Peat appears to have been long in use, as fuel, in different parts
of Germany. Thus JEneas Sylvius Piccolominaeus, in 1458, in his
History of the Military Transactions of Frederic III. having occa-
sion to speak of some part of Friesland, rendered worthy of notice
by some interesting military event, describes it as " a smooth and
marshy plain ; abounding in grass, but without wood. The inha-
bitants supporting their fires by a bituminous turf, mixed with the
dried dung of oxen."

Ludovicus Guicciardinus, who wrote very early on the geography
and natural history of Holland, remarks, that the combustible
turf called by the names of torff or turf, which abounds in Holland,
is of so much consequence as to have had the strongest claim to his
attention.

CuthbertTonstall, Bishop of Durham, in the reign of Henry VIII.
notices the very general use of turf, as fuel, in Zealand ; the heavy
inconveniences, arising from the smoke of which, he complains of
to Erasmus in a very energetic lamentation. If, says he, you remain
at home in the city, the smoke of the turf (for, says he, they burn
this in the place of wood) fills your nostrils from the surrounding
neighbourhood. These, when dug from moist and salt places, how-
ever much they may have been dried in the sun, yield a smoke,
whilst they burn, which penetrates into your very breast, and at-
tacks, at once, your nostrils, head, and chest.

Turf, it is probable, might be found in most parts of the world :
the lowlands of almost every country of Europe possess it, and it
particularly abounds in many parts of Holland and of Germany,
in Brabant, Transilvania, Groningen, Zealand, Friesland, England,
Scotland, and Ireland, and indeed in all the northern parts of Eu-

* Anderson on Peat-Moss.
VOL. I. N

90

rope : being, in several places, the only fuel which the inhabitants
can obtain*.

Caesalpinus observes, that in CEland, a peninsula in the Nether-
lands, a black mud is obtained from the marshes, which, being made
into clods, and dried, is used for the purpose of making up fires,
being rendered a species of coals -f-.

Jonas Arngrim, who wrote in 1592 says, that the peat which is
dug for fuel in Iceland, is of two kinds ; the one, which is found
growing immediately under the surface of the earth, he observes, is
light and spongy ; whilst the other, which is much deeper in the
ground, and is dug up from the pits, is more heavy and dense J.

Quado § says, that in West Friesland the earth is fatty and bitu-
minous ; and that, being dried in the wind, it serves for fuel in-
stead of wood ; but is very different from the coal of Namur, Liege,
Hanault, &c.

Libavius || says, the inhabitants of the lower parts of Germany
employ for fuel that which they term darry and dorfen, which is, he
says, a mass of roots, blended with a bituminous earth.

Schoockius, who wrote expressly on peat in 1658 ^f, and does not
admit its vegetable origin, thinks that Libavius should rather have
said, that the bitumen in certain peats is so coloured and diversified
as to resemble dried roots.

Darria, derrie, or darinck, derived from the Danish word dar-
ren, signifying to burn, he says, is a substance which, even at that
time, was dug in Zealand, and chiefly in Wallachia, for fuel. He
describes it as a bituminous matter, thrown on shore by the sea,
and which has been afterwards covered by the earth. At one time
it was dug, with so much eagerness, for the salt, which, by certain

* Erasmi Epistol*. lib. iii. t Andr. Caesalpin. lib. .ii. cap. 53.

J Brevis Commentarius de Islandia, Hoolum. 1592. § Lib. iv. cap. 37.

U Lib. iv. de Origine Rerum.

^ Martini Schoockii, Tractatus de Turfiis seu Cespitibus bituminosis. GroningaB51658.

91

processes, it was made to yield, that a strong law was passed, to pre-
vent the farther digging for this substance, lest the shore should be
SQ weakened, that it would not be able to resist against the violence
of the waves. In the year 1515, however Charles V. harassed by
the petitions of the poor, who had no other means of obtaining fuel,
was again obliged to permit it to be dug.

Mr. Tooke informs us, that in Siberia, there are great plenty of
morasses, and of various magnitudes. Thus the northern verge of"
Siberia, towards the shores of the Frozen Ocean, for several hundred
versts in width, is one prodigious watery morass, grown over with
moss, and entirely destitute of wood, and which, in summer, is
only thawed to the depth of about a span *. In the interior of the
empire we meet with smaller; and many of the forests have a
swampy bottom. He describes them as — 1st, simply low watery
land; — 2d, swamps, which yield turf formed out of the moss, and
even at times produce a little hay ; — 3d, bottomless morasses, which
appear to be lakes grown over ; they frequently will bear neither
man nor beast ; — 4th, moss -morasses, the deep and useless moss of
which will permit neither grass nor a shrub to grow, or at most,
only a few wretched low sticks of fir, &c. which presently wither
and die. They are absolutely unprofitable; or at least they are
held to be so-f .

Dr. Woodward observes, that marsh or tuif earth, containing in
it nuts, twigs of trees, shrubs, grass, sedge, &c. is found in various
parts of England. He particularizes several places, where it is found
to abound very much. He obtained it from Hampstead Heath,
and from Godalming, in Surrey. At Wilmestow, near Knutsford,
in Cheshire, it lay uppermost in the moss, and next the surface ;

* Pallas's Travels, vol. iii. p. 23.

t View of the Ruaan Empire, &c. by William Tooke, F.R.S. London, 1390, p. 11.

92

and seemed to be made up only of the shivers, or husks, and other
parts of juli of hazel, alder, poplar, £c. There is also great quanti-
ties of this kind of turf in the northern parts of Yorkshire, and in
the bishoprick of Durham. About a mile from Langrow, in Cum-
berland, is a stratum of bituminous earth, three feet thick, which
contains parts of the trunks of trees, leaves, sprays of shrubs, and
other vegetable substances, in such quantity that the far greater
part of the stratum seemed to be formed by them. It also abounds
near Outhorn in Yorkshire, at Kendall in Westmoreland, in Wind-
sor Forest, in the Isle of Wight, and various other places. In that
which was dug up in the Isle of Wight, besides the twigs and leaves
of hazel, were found several hazel nuts, the shells of which were un-
broken, but the kernels were decayed.

How extensive and considerable the beds of peat may be in the
vicinity of the metropolis, may be inferred from the following cir-
cumstance:— Near a hundred years ago, in digging a wet dock at
Deptford, hazel nuts, with hazel, oak, and several other kinds of
trees, were found. Within these few years, in digging the wet-docks
of Mr. Perry, at Black wall, on the opposite side of the river, and at
the distance of nearly two miles, a similar stratum was dug into,
yielding peat for a considerable thickness, in which were found
hazel nuts, trunks of large trees, &c. In digging also, in the ad-
joining marshes, called the Isle of Dogs, lately, for the purpose of
forming similar docks, wherever the earth was opened, over an
extent of several acres, peat was also found, with hazel nuts, and
several trees ; these were chiefly oak, yew and hazel, and a few firs :
but the latter, as I am informed, were but of a very small size. At
the depth of about six, eight, or nine feet were also found bones of
several animals, apparently of horses and oxen, and the fragments
of the horns of deer.

In almost every morass, which has been dug in the isles of An-

glesey and Man, in Somersetshire, Cheshire, Lancashire, Yorkshire,
Staffordshire, Lincolnshire, and indeed in almost every county of
England, has this substance been found.

In the account given by Captain John Perry, of the stopping of
Dagcnharn Breach*, that able engineer particularly describes what
he terms the moor-log. This, he says, was composed of vegetable
matter heaped together, but seemed chiefly to be composed of
brush wood, among which there appeared to be a considerable
quantity of hazel trees; hazel nuts themselves were also found in
this mass, and were very fair to look at, but were easily crushed,
the kernel having entirely perished. In the mass were also con-
tained the trunks of several trees, of which, he thinks, the trunks of
the yew trees, some of which were about fourteen or sixteen inches
in diameter, were the least decayed. The willow trees, which were
two feet and upwards in diameter, retained a whitish colour like
touchwood, and were even softer than the adjoining earth or moor-
log. The moor-log appeared at about three and a half or four feet
under the marsh ground, and differed in thickness, in different parts.
Up the Thames, at Deptford, it was six feet in thickness. In Wool-
wich Reach, where Captain Bronsden had then been repairing his
wharfs, over against the ballast wharf, it was between seven or
eight feet thick. In Plumsted Levels, just against Barking Creek,
its thickness was full nine feet ; its thickness, as well as its breadth,
gradually increasing down the river, on both sides. None of it, he
says, was to be seen where the course of the river, cuts into the
high-land, as at Woolwich, Erith, and Purfleet. Beneath the moor-
log was a stratum of blue clay, and under this gravel and sand,
Stags' horns were likewise found in different places, a little above
the vein of moor-log.

The description of the peat at Newbury, in Berkshire, will serve

* An Account of the Stopping of Dagenham Breach, by Captain John Perry,
1731. p. 72.

94

to give a tolerably correct idea of the appearances it generally pre-
sents in this country ; and will also show that it does not seem to
differ, in any thing material, from that, which we have seen, exists
in the other parts of the world *.

The peat is found in the middle of a valley, across which the town
of Newbury lies, north and south. The river Kennet runs along
the middle of this valley, which is about a mile broad, and the peat
is found on mcli side of it, extending in all, for about a quarter of
a mile, to about half a mile in breadth; and in length, along the
valley, about nine miles westward, and about seven miles eastward.
It is supposed to reach much further; though perhaps, with some
intermissions.

The top of the true peat is found at various depths, from one foot
to eight feet below the surface of the ground ; a,nd the depth or
thickness of this peat is also very different, from one foot to eight
or nine feet ; the ground below it being very uneven and generally
agravel.

The best and most perfect peat has very little, if any, earth in it;
but is a composition of wood, branches, twigs, leaves, and roots of
trees, with grass, straw, plants, and weeds ; which lying continually in
water becomes soft, and easy to be cut through with a peat-spade.
The colour is of a blackish brown, and if it be chewed between the
teeth, it is soft, and has no gritty matter in it. It is, indeed, of a
different consistence, in different places ; some being softer and
some firmer and harder; which may, perhaps, arise from the differ-
ent sort* of trees it is composed of.

Great numbers of trees are plainly visible in the true peat, lying
irregularly one upon another ; and sometimes even cart loads of
them have been taken out, and dried for firing : but the nearer these
trees lie to the surface of the ground, the less sound is the wood ;
and sometimes the small twigs, which lie at the bottom, are so firm,

* Philos. Trans, vol. L. part i. p. 109.

as not to be easily cut through with the usual peat-spade. These
trees are generally oaks, alders, willows, and firs, besides some others
not easily to be known. The small roots are generally perished ;
but yet have sufficient signs to show, that the trees were torn up by
the roots, and were not cut down, there being no sign of the axe or
saw ; which, had they been felled, would have been plainly visible.

No acorns are found in the peat, though many cones of the fir
tree are, and also a great number of nut-shells. They are all of a
darkish colour; and the nuts are hollow within, and some of them
have a hollow at the broad end.

A great many horns, heads and bones of several kinds of deer,
the horns of the antelope, the heads and tusks of boars, the heads
of beavers, &c. are also found in it i and I have been told, says the
learned gentleman who transmitted the account to the Royal So-
ciety, that some human bones have been found, but I never saw
any of these myself, though I have of all the others.

Mr. Aikin, whose Journal of his Tour through North Wales is
replete with most interesting and useful remarks, speaking of the
vallies among the mountains of Llangynnog, Cader-Ferwyn, and
Sylattyn in North Wales*, says, the soil is peat, a yard or more in
depth, lying upon a thin stratum of rounded pebbles, chiefly quartz,
with some schistus ; the bottom of the bogs is a grey clay, formed,
probably, from the decomposition of the rock. Near Aberdovey, in
Merionethshire, he observed a considerable peat-moss, extending
along the shore to Tomyn, reaching into the sea to an unknown
extent, from which the inhabitants dig their fuel.

Whole bodies of trees, according to the relation of Dr. Gerard
Beate, are frequently found, in Ireland, by the turf diggers, very
deep in the ground. And it is worthy of observation, he says, that
trees and trunks of trees, are in this manner found, not only in the
wet bogs, but even in the heathy ones, or red bogs ; as in that by the

* Page 92.

96

Shannon side, in which bog the turf diggers do many times find whole
fir trees, deep in the ground : whether it be that those trees being
fallen, are by degrees sunk deeper and deeper, or that the earth
in length of time be grown over them*.

Not only the presence of fossil trees in beds of turf, but also the
existence of this substance at a prodigious height, is related, by
Villars, professor of natural history of Grenoble, in a paper read
before the National Institute of France. He relates, that on the
mountain of Lans, in the canton of Oisau, in the department of
Isere, he discovered a bed of turf at between seven and eight thou-
sand feet above the level of the sea, and at nearly three thousand
feet above the most elevated line at which any trees grow at pre-
sent. The trees were not so much changed, but that the roots and
parts of the trunks were plainly distinguishable, shewing that they
were mountain-ash, birch, and the common larch; the two first of
which only, at present, grow in that neighbourhood.

Similar instances of the existence of beds of this substance, on
very high mountains, we have, as has been already remarked, in
various parts of the world. In Scotland, it has been particularly
noticed: where also a very curious circumstance is observable, the
existence of two beds of turf separated by several strata of a con-
siderable degree of thickness. My much esteemed friend, Mr.
Wakelin Welch, of Exmouth, Devonshire, informs me, that he has
seen in the mountains of Scotland, two beds of turf, with several
intervening strata; that stratum which lay immediately over the
lowest bed of turf, containing a considerable proportion of shells,
intermixed with sand. A remarkable instance of this kind occurred
in the sinking of a well at Amsterdam, where, in the course of se-
venty-three feet, turf was found to occur twice, a variety of strata
intervening. This account which I found among the manuscript
papers of the Royal Society is as follows -j- :

*The Natural History of Ireland, by Dr. Gerard Boate, 1652, p. 63.
t Mr. Ayscough's Catalogue, 698, 5.

-.^a 97

An Account of the Ground of a Water-Pit, bored at Amsterdam^
presented to the Society by Mon. Huygens de Zulichem.

In the year 1605, the 15th of July, a water pit was bored at Amsterdam, in the hos-
pital of old men, 232 feet deep, (which is some 32 feet higher than the steeple of the
old church there) and the ground was found as followeth :

Feet.

1 Stony and garden ground 7

2 Fen and dairy (turf) 9

3 Soft clay 9

4 Sand 8

5 Earth 4

6 Clay 10

7 Earth 4

O I

8 Here followeth the sand on which most part of

Amsterdam is founded 10

9 Clay 2

10 White sand ' 4

1 1 Dry earth 5

12 Turf bruised 1

13 Sand . . . . 14

14 Sandy clay 3

1 5 Sand and clay mingled 5

1 6 Sand and sea shells . 4

17 After these ninety-nine feet, there is a couch of

clean clay of 102

18 Sand, in which the boring ended 31

135

232 feet.

In the foregoing account, Mr. Huygens, remarks, one thing is par-
ticularly observable, the occurrence of turf twice in the same boring,
once immediately below the vegetable mould and gravel (stony
ground), and again at the depth of seventy-two feet.

Various opinions have been adopted respecting the origin of
peat, arising from the different appearances yielded by it in differ-
ent situations. Many were of opinion, that it had obtained the
form in which it now appears, at the creation of the world ; the vast

VOL. i. o

98

quantity in which it was found, and its extreme utility, seemed to
give some countenance to this opinion. Some have supposed it to
have originated in the deposition of a bituminous mud by the waters
of the sea, which, they imagined, must, in very remote periods, have
inundated all those parts, in which peat is so plentifully found. The
strong resemblance which this matter frequently bears to the re-
mains of trees and other vegetables, induced others to attribute its
formation to the overwhelming of vast forests, by inundations of the
sea ; they accounting for the depth at which it is found, as well as
for its superincumbent strata, from the quantity of earthy matter
which so violent a rush of waters must carry with it, and deposit on
those tracts on which it rested. Others have conceived, that it
must have proceeded from the forests which were prostrated at the
time of the deluge recorded by Moses ; and that it derived its in-
flammability from some peculiar change, which they underwent at
that period.

Schoockius was decidedly of opinion, that peat was entirely of
mineral origin, and says, that the straws, twigs, and a thousand
other things, which appear to be blended accidentally with it,
have been formed thore by nature: and adds, if any one demand
how these things came in the deep recesses of the earth, I will tell
him, in the first place, that they may be generated there, in the man-
ner spoken of by Pliny ; and secondly, that the bituminous filaments
possess the power, by their various dispositions, of assuming these
forms. Thus he also accounts for the formation of the substances
resembling trees, branches, and pieces of roots, which are frequently
found among the peat. These, he supposes, have grown there, in
the same manner as other fossil substances. A confirmation of this
opinion he derived, from the circumstance of several of the trunks
possessing, not a round, but an oval shape ; a form which, he ob-
serves, ordinary trees never assume. He at the same time, acknow-
ledges, that the resemblance which the fossil trees bear to real pines

99

is so great, that the peat-pits are called by by the common people
keenen, kien-bomen, or kien-hout ; kien or keen, being the word
which, in the German language, signifies pine.

In a similar manner he endeavours to account for the pine nuts
or cones, which are found amongst the peat. If they be real pine-
nuts, they must, he says, astonish every one ; for although the pine
is found in considerable numbers near to Breda, in Brabant, yet it
is seldom found in any other part of Belgium.

Although he cannot but admit, that, formerly, pines might have
grown on these spots, and have been there overthrown and preserved,
with their nuts, from putrefaction, by the including matter ; yet he
cannot allow that all those resinous balls, mixed with, and resem-
bling those bodies, which he admits to be pine nuts, can possibly be
real nuts ; but he rather supposes them to be of the same nature
with other bituminous masses, some of which, not unlike to walnuts,
and others to eggs, are sometimes met with whilst digging. The only
difference, he thinks, is that, in the seeming pine nuts, there is an
admixture of sulphur and other things, which render them of a
resinous nature, similar to the real cones.

Some also have attributed the formation of peat to the sinking
of large floating islands, such as are now frequent in several parts
of Holland, and such as have been known to have existed in very
early ages ; Seneca and Pliny having noticed the existence of a
lake, on which was a floating island, near to Cutila, a town of the
Sabines*.

Dr. Plott, in his Natural History of Staffordshire, relates, that at
that period there were two floating islands on Kinson Pool, which
were about twenty feet broad, and about thirty, or perhaps forty,
feet long.

o

The utility of this substance, in those parts in which coal is not

^Seneca? Natur. Quest, lib. iii. cap. 16. Plin. lib. iii. cap. 12. lib. xxxi. cap. 2.

ioo

dug, has been already noticed. But the thick acrid smoke, and the
disagreeable odour which turf yields, whilst it is burning, very much
limits its utility ; it has, therefore, been attempted to remove these
inconveniences, by submitting it previously to the action of fire, ex-
cluding it, at the same time, as much as possible, from any commu-
nication with the open air ; in the same manner as in the operation
for the making of charcoal from wood, or coke from coal. The at-
tempt has succeeded in some degree ; but still the charcoal of turf is
very inferior to that of wood, and is, besides, liable to inflame, if ex-
posed to the combined action of air and water ; whence arises the
necessity of its conservation in magazines that are well covered in.
Fourcroy gives a very interesting account of a spontaneous com-
bustion of this substance, produced in this manner. He says, I
saw at Paris a timber yard, carefully filled with this charcoal, form-
ing a vast pile, open to the air. After being for some days ex-
posed to the continual action of the rain, it exhaled an abundance
of white smoke, which soon changed into flame, and the whole
charcoal became thus consumed ; threatening every instant to pro-
duce a vast conflagration, by communicating with the neighbour-
ing combustible bodies*.

Yours, &c.

* Systeme des Connoissances Physiques, torn. viii. p. 229,

101

LETTER XL

BITUMINOUS WOOD....SURTURBEAND OF ICELAND. . ...BXTt'JBYv COAL

OF ENGLAND.

/,./•.-_.•

i REVIOUSLY to offering, for examination, the opinion which I en-
tertain, respecting the nature and the formation of peat, it will be
proper to call your attention to some other substances, the origin
of which has hitherto appeared to be equally doubtful. The neces-
sity of furnishing you with the most material facts, which have
been noticed, respecting these substances, before I attempt to com-
municate my ideas respecting the nature and the formation of peat,
will, I trust, plainly appear, when I shew you the connection which
appears to exist between it and those several substances ; and when
I also endeavour to demonstrate, on what principle the formation
of all these substances depends.

The substance, with whose nature and properties I shall next en-
deavour to make you acquainted, is that which in Iceland is called
surturbrand, and which, in this country, is chiefly known by the
name of Bovey Coal.

The ligniform appearances, which bituminous substances some-
times bear, have been long known, and even the particular kind
which we are now about to examine, has been noticed by some of
the early writers in natural history. This substance, although pos-
sessing all the properties of bitumen, bears the distinctive marks of
wood, but generally in the form of splinters or chips ; or, if in larger
masses, these are very capable of being divided into such fragments,
even with a very slight force.

Theophrastus states, that there is found, in the mines of Scapte-
sylae, a stone, in its external appearance something resembling rot-

102

ten wood : on which, if oil be poured, it burns ; but when the oil is
burnt away, the burning of the stone ceases, as if it were in itself
not liable to such accidents*.

.-The description which Galen gives of certain black stones,
brought by him, out of Coelosyria, seems to accord very exactly with
the Bovey.Coal,or surturbrand. He describes them as being broad
like a board, and on being put into the fire, burning with a slender
flame. They were generated, he says, in the hills on the east side
of the Dead Sea, where the bitumen is produced, and the smell of
the stone was like bitumen f.

Agricola mentions several places in which bituminous wood has
been found, but is most particular in 'his account of that which is
found in a celebrated mountain in Misena, not far from the city of
Zuicca, where, he says, after digging about a step deep through
common earth, they find an extensive vein of soft coal, about three
steps and a half deep, and then cutting through a tolerably thick
stone, they again arrive at coals, but these are hard, and have ob-
tained the name of pitch coal, from their blackness and brightness.
Under this vein they find a bituminous metallic earth, beneath
which are scattered aluminous pyrites, coal, &c. J

Valerius Cordus relates §, that light, dry wood, black like coal,
is dug out of the mountains of Marienbergen, at the depth of forty
orgyia.

Schoockius describes the fossil wood of Meizlibizen, as being of
the same kind as that of which we are here treating of. He says,
speaking of it under the conviction of its being intirely of mineral

origin, that it is exceedingly like to vegetable wood ; but, that the

i

* Theophrastus, History of Stones, translated by Sir John Hill, p. 67.
t De Simplicium Medicamentorum Facultat. lib. ix.
$ De Natura Fossilum, Basil. MDLVIII. lib. vii.-p. 325,

§ Valerii Cordi Observationes quaedam Rerum naturalium variarum, & primum Fos-
silium in Germania. MDLXI. p. 217.

103

fibres are very confused ; the same fibres running straight, oblique,
transverse, circular, and indeed in every possible direction, which,
he observes, is never the case in vegetable wood.

Pillingen, who wrote expressly on the fossil wood of Meizlibizen,
in Misnia between Ziza and Altenberg, gives the following accu-
rate description of it ; he entertaining the same opinion of its mi-
neral origin with Schoockius. Whilst digging in a valley, at the foot
of a mountain, near Altenberg, which had been deepened by fre-
quent strong currents of rain water, flowing from this and the adja-
cent mountains ; wonderful, he says, to behold, at a little distance
from the surface, they found a substance like decayed wood, capable
of being inflamed; bearing marks resembling those which result
from an annual increase ; and, in a word, so formed, by nature, that
water was not more like to water, nor milk to milk, than this mine-
ral wood, thus formed by nature, was to vegetable wood. The fibres
of this wood, unlike to vegetable wood, were contorted and twisted
in almost every direction, and it was generally found split into slices
or chips. It was very light, except when containing pyrites, and
its colour was a darkish brown. Whilst burning, it yielded a sul-
phurous or bituminous smell, and was thereby resolved into a light
white earth, not unlike to amianthus, or plumose alum. White,
hard, and exceedingly heavy pyrites, and particles of sulphur, he
observes, were found very abundantly in this vein of fossil wood.

Beneath this layer of wood, the earth was strongly bituminous for
nearly seven feet deep, and differed hardly in any thing from the
wood itself, except that the fibres, which were distinguishable in
the wood, were not here to be discovered of the same length : it was
also much more frequently divided by clefts.

At first, on perceiving that this wood was so light as to swim on
wnter; that it inflamed on being ignited; that it bore the marks of
the long veins of wood ; and, that it even had knots from which the
boughs appeared to have grown ; he concluded it to be real wood,

104

which had been immersed in water, and had suffered decay.
But he soon, however, changed his opinion, when he considered,
how prodigiousthe quantity was of which it consisted ; which, he
thought, must have been vastly beyond what could have been fur-
nished by any forest. Again, had it been of diluvian origin, he ex-
pected, that he should have found the vegetable ruins scattered, in
detached and irregular masses ; but here the vein of bituminous
matter had, every where, an uniform appearance, and constantly
preserved the same rectilinear course, undisturbed by the inequa-
lity of the mountain. Besides, in this wood, he could discover no
transverse fibres ; nor could he find with it either bark, branches, or
leaves. From these circumstances, he was induced to relinquish
the opinion, that it had ever belonged to the vegetable kingdom ;
and concluded it to be entirely of mineral origin. Bitumen possess-
ing, in his opinion, a peculiar innate, and to us a hidden power of
coagulating and assuming the form of wood ; this being a work not
of the subterranean archceus, but the result of a specific power in-
herent in the bitumen.

Above and beneath this stratum of bituminous matter, is a bed of
very fine potter's clay, about six feet thick, which keeps the same
horizontal level, and passes along with the fossil wood, directly in a
straight line, through every recess of the mountain, neither rising or
declining with its slope *.

Francisco Stelluti, in 1637, described some strata of fossil wood,
found near Todi and Aqua Sparta, in Umbria ; the description of
which exactly accords with the kind which we are at present ex-
amining, in its consisting of large oval and compressed pieces, lying
horizontally, resembling the trunks of trees, but larger, some being
above three feet broad ; in having neither roots, branches, nor fibres,
but something like bark ; and something resembling the heart of

* Bitumen et lignum fossile bituminosum descriptum a D. Matthia Zaccharia Pil-
lingen, medico Altenburgensi. Altenbergi, anno 1674.

^ 105

the tree, but as hard as a bone, and in some as black as a coal.
Similar to the Bovey Coal, its veins, instead of running straight, like
the fibres of wood, were undulated and irregular, taking a variety of
forms, and were only superficial ; for, upon taking off one of the
thin laminae of which this fossil was composed, the veins under-
neath appeared in a different direction. This fossil, when first taken
out of the earth, burnt like a bone; and consumed slowly in the
fire, with a considerable smoke and disagreeable smell; but if dried,
before it was burnt, the smell was more pleasing. Many of the
pieces, he observes, were sprinkled with pyrites ; and there exudes
from some parts of it, a white bituminous substance, like rosin.
Stelluti is convinced, that this ligniform matter is not of vegetable
origin, but supposes it to be generated from a cretaceous earth,
transforming itself into wood, by the assistance of sulphurous
water, minerals, and subterraneous heat ; a thick smoke, and some-
times even flames appearing, particularly in rainy weather.

Gassendus, in his Life of the illustrious Peireskius*, describes the
fossil wood of Aqua Sparta, which had been just discovered. There
were only found, he says, portions resembling trunks, but no ves-
tiges of branches, knot, or roots ; which yielded an argument, as it
were, that woods might be generated and concreted in this form,
and not, according to the vulgar, derived from wood overthrown
and become petrified

Professor Hollman, of Gottingen, presented to the Royal Society
a paper, which appeared in the second part of the fifty-first volume
of the Society's Transactions, with the title of Montium quorundam
pr&altorum, magna Ligni Copia quasi infarctorum, brews Descriptio ;
and in 1784 he republished it with some additions, at Gottingen,
under the title of Loci memorabilis, in quo ingens Ligni fossilis Copia
reperitur, Descriptio.

From these accounts, it appears that, near the city of Munden,

* Vita illustris Peireskii, lib. v. 1637.
VOL. I. P

106

and in that point of land which is washed by the rivers Werra and
Fulda, as they unite to form one stream, several mountains succes-
sively arise. On the top of one of the loftiest of these, which is
about 1150 feet in height, is found a layer of mould of about a foot
and a half, or two feet thick, under which is a stratum of yellow-
ish clay, of two or three feet in thickness ; and another, of a brown
colour, considerably impregnated with alum and sulphur; and
beneath these so large a quantity of fossil wood, as would almost
exceed the belief of any one who had not seen it. The professor
himself at first doubted, whether it was really fossil wood or not ;
but it was not long before he became fully convinced, that it was
indubitably of vegetable origin : he discovering not only the longi-
tudinal, but with a glass, even the transverse fibres ; and by a trans-
verse fracture the marks of the wood's annual increase. This wood
existed almost entirely in small fragments, lying very compactly
on each other ; each fragment being divided by numerous fissures,
so as to render it difficult to form any opinion of the real size
of the trunks, or branches, which they originally formed. Nor,
during all the time which they had dug for this wood, had they
ever met with any of length sufficient to show the branches ; neither
had they discovered any leaves, or any fragment still retaining its
circular form. The professsor, however, saw a trunk with a por-
tion of the roots still adhering, fully impregnated with pyrites.
On another piece he observed the traces of leaves sufficiently
evident. Frequently, he remarks, are pieces of wood found, not
merely almost surrounded with pyrites, but so fully impregnated
with them, that although the situation and form of the several parts
of the wood are exactly preserved, its conversion into pyrites appears
to be entirely complete. Some of the specimens of this kind are
described as being most elegant in their appearance, but unfortu-
nately soon falling into pieces when exposed to the air ; their surface
first, as it were, exuding sulphur and alum in a pulverulent form.

107

To prevent this decomposition and destruction of his more va-
luable specimens, he adopted the practice of washing off the salts
from them, by two or three times in the day jpouring boiling water
over them ; and thus he had preserved some for the space of three
or four years.

The quantity of this fossil wood appears to have been truly pro-
digious. The stratum, of which we have hitherto spoken, was about
twenty feet in depth, the bottom of it resting on a stratum of stone,
about a foot in thickness. On piercing this, another stratum of
fossil wood was found : to discover the depth of which several at-
tempts were made ; but although the borers passed to the depth of
thirty feet, they did not reach to the bottom of this stratum. Hence
it was only ascertained, that the fossil wood was at least fifty feet
deep ; since they were unable to determine to how much greater
a depth the stratum reached. A difference was observable in the
two strata, which merits our particular notice : the fossil wood con^
tained in the upper stratum, was of a light brown colour; but that
in the inferior stratum, was of a much darker brown, verging upon
black.

The earth, which lay over the fossil wood, not only had the same
brown colour for more than half a foot in thickness, but was im*
pregnated with similar sulphurous and aluminous particles, and
even yielded almost as good fuel.

Taking advantage of a passage which had been dug into the
body of fossil wood, the professor passed nearly two hundred feet
in length within it, so that the roof, fioor, and sides of the place, in
which he stood, were entirely composed, of what he esteemed, a
mass of vegetable ruins. Here the water, which had insinuated it-
self in the top of the mountain, was found dripping through the
roof; and sulphurous and aluminous matter were found to exist,
in an equal proportion with that which pervaded the other parts of
this mass. Between the fossil wood was seen, in some places, a

108

vein of hard, blackish bitumen, possessing almost the hardness and
splendor of jet. This vein of indurated bitumen was a foot, and
even more, in thickness. The professor saw, also, some specimens
of marble, from this mountain, containing small bivalves; and
obtained, from the same mountain, two marine shells, the one in
a petrified, and the other in a pyritified state ; as well as a most
elegant serrated tooth, resembling those of the shark, which mea-
sured three inches and a half in height. Hence he concludes, that
this mountain must, at some former period, have been covered by
the sea.

The indefatigable Rosinus, who also visited this mountain, re-
lates, that a large quantity of potter's clay is dug here, and fre-
quently with it fragments of wood, with black bitumen, and some-
times pyrites. He also describes hard flint stones, containing
charcoal ; and reeds, or at least their impressions, which, with an
abundance of marine remains, were dug out of the bowels of the
earth, in the same mountain.

Professor Hollman also gives us, in the same work, a particular
description of the circumstances, most worthy of notice, which he
perceived in the examination of a mountain, near AltendorfF, so
famous for its salt-works, on the borders of Hesse. The height of
this mountain appears to be about 2500 feet, exceeding that of the
mountain, just described, in the neighbourhood of Munden, full
seven hundred feet. His astonishment was here still more excited
than when contemplating the wonders of the former mountain.
Under an immense roof, formed by a vast stratum of stone, which
was from eighty to a hundred and forty yards in thickness, was a
vein of fossil coal, in most places of upwards of twelve feet in depth,
which had long been dug to supply fuel for the neighbouring salt-
works, and of which an incalculable quantity still remained. This
fossil coal, resting on a bed of bituminous wood, agreed almost in
every respect with the small vein of bitumen he had observed

109

in the interior passages, which had been dug in the mass of fossil
wood, in the former mountain : possessing, like it, the brightness
and hardness of jet. In proportion, also, as the fossil wood lay near
to its superincumbent stratum of fossil coal, it was evidently the
more impregnated with bitumen ; possessing a darker colour and
a greater degree of compactness. That which was at a greater
distance from the vein of coal, being situated still lower, differing not
much in its colour, and general qualities and appearance, from com-
mon decayed wood. It is a circumstance worthy of particular
attention, that the stratum of stone, at its inferior surface, was so
exactly adapted to the upper surface of the stratum of coal, as to
give the idea, of a fluid matter having been poured over the sub-
jacent hard and coherent stratum. In the same manner, also, did
the lower surface of the fossil coal apply to the superior surface of
the fossil wood.

In the same volume of the Philosophical Transactions * which con-
tains Professor H oilman's more abridged account of this fossil wood,
is also a paper by the Rev. Dr. Jeremiah Milles, entitled " Remarks
on the Bovey Coal." Dr. Milles observes, that the fossil wood de-
scribed by Professor Hollman corresponded in many particulars
with some strata, discovered about fifteen years before, in Devon-
shire, and which he was satisfied were not of vegetable origin : and
concluded therefore, that the substance described by Professor Holl-
man. likewise, was not wood. The account of this fossil, the Bovey
Coal, as given by Dr. Milles, is highly interesting, and is therefore
here given in his own words.

" It is found on a common surrounded with hills, called Bovey
Heathfield, in the parish of South Bovey, thirteen mile south-west
of Exeter, and three miles west of Chudleigh. The uppermost of
these strata rises within a foot of the surface, under a sharp white
sand, intermixed with an ash-coloured clay, and underlies to the
south about twenty inches in a fathom.

*Philos, Trans, vol. li. part 2, p. 534.

110

" The perpendicular thickness of these strata, including the beds
of clay with which they are intermixed, is about seventy feet.
There are about six of each, and are found to continue eastward, in
an uninterrupted course, to the village of Little Bovey, a mile dis-
tant; and probably extend much further. The strata of coal, near
the surface, are from eighteen inches to four feet thick ; and
are separated by beds of a brownish clay, nearly of the same
dimensions, but diminishing in thickness downwards, in propor-
tion as the strata of coal grow larger ; and both are observed to
be of a more compact and solid substance, in the lower beds.
The lowermost stratum of coal is sixteen feet thick ; it lies on a
bed of clay, under which is a sharp green sand, seventeen feet thick,
and under that a bed of hard coarse clay, into which they have
bored, but have found no coal. From the sand arises a spring of
clear blue water, which the miners call mundic water, and a water
of the same kind trickling through the crevices of the coal, tinges
the outside of it with a blue cast.

" Beneath this was an equal, if not a greater, quantity of fossil
wood, with that which existed in the mountain already mentioned.
With that wood it appeared, in general, to agree pretty much in its.
nature and appearance ; it however did not seem to be accompanied
by so much mineral salts as the other.

" Some small, and narrow veins of coal, are found intermixed with,
and shooting through, the beds of clay ; bearing impressions, like
those of reeds and grass ; and very similar to those which are found
on the top of coal mines. The clay also, at least that part of it
which lies nearest the coal, seems to partake of its nature, having
somewhat of a laminous texture ; and being, in a small degree, in-
flammable. Amongst this clay, but adhering to the veins of coal>
are found lumps of a bright yellow loam, extremely light, and so
saturated with petroleum, that they burn like sealing-wax, emitting
a very agreeable and aromatic scent.

Ill

" Though the substance and quality of this coal, in its several
strata, are much alike, and it is all indiscriminately used for the
same purposes ; yet there is some difference in the colour, form,
and texture of the several veins. The exterior parts, which lie
nearest to the clay, have a greater mixture of earth, and are ge-
nerally of a dark brown, or chocolate colour ; some of them appear
like a mass of coal and earth mixed ; others have a laminous tex-
ture, but the Iamina3 run in such oblique, waving, and undulating
forms, that they bear a strong resemblance to the roots of trees, of
which kind, the Doctor says, I have seen some specimens from
Lough Neagh, in Ireland, which seem to be the same sort of fossil.

" There are other veins of this coal, which lie more in the centre
of these strata, and abound most in the lowest and thickest bed,
the substance of which is more compact and solid : these are as black,
and almost as heavy, as pit-coal ; they do not so easily divide into
laminae, and seem to be more strongly impregnated with bitumen :
these are distinguished by the name of stone coals, and the fire of
them is more strong and lasting than that of other veins.

" But the most remarkable and curious vein, in these strata, is that
which they call the wood-coal, or board-coal, from the resemblance
which the pieces have to the grain of deal boards. It is sometimes
of a chocolate colour, and sometimes of a shining black. The for-
mer sort seems to be less impregnated with bitumen, is not solid
and heavy, as the latter, and has more the appearance of wood. It
lies in straight and even veins, and is frequently dug in pieces, of
three or four feet long, and, with proper care, might be taken out
of a much greater length. Other pieces of the same kind are found
lying upon them, in all directions, but without the least intermix-
ture of earth, and without any interstices, except some small cre-
vices, by which the pieces are divided from each other, in all di-
rections. When it is first dug, and moist, the thin pieces of itwill
bend like horn ; but when dry, it loses all its elasticity, and becomes

112

short and crisp. At all times, it is easily to be separated into very
thin laminae, or splinters ; especially if it lie exposed any time to
the heat of the sun ; which, like the fire, makes it crackle, separate,
and fall to pieces.

" The texture of this fossil consists of a number of laminae, or
very thin plates, lying upon each other horizontally, in which small
protuberances sometimes appear, like the knots of trees ; but upon
examination, they are only mineral nuclei, which occasion this in-
terruption in the course of the laminae; and pieces of spar have
been sometimes found in the middle of this wood-coal. Though
the texture of this coal is laminated, yet it does not appear to have
any of those fibrous intersections, which are observed in the grains
of all wood. This coal easily breaks transversely, and the sepa-
rated parts, instead of being rugged and uneven, are generally
smooth and shining, in which even the course of the laminae is
hardly discernible.

" When this coal is put into the fire, it crackles, and separates
into laminae, as the cannel-coal does into irregular pieces ; burns for
some time with a heavy flame ; becomes red hot, and gradually
consumes to light white ashes. Though the transverse crevices,
made in it by the fire, give it the external appearance of a wooden
brand, yet, if quenched when red hot, the unconsumed part does
not look like charcoal, but seems to be almost as smooth and solid
as when first put into the fire.

" The thick heavy smoke, which arises from this coal when burnt,
is very foetid and disagreeable; entirely different from that aroma-
tic scent of the bituminous loam, which is found adhering to it;
but much resembling that of the asphaltum or the bitumen of the
Dead Sea. The most shining and solid pieces of this coal have
not the least degree of electrical attraction/'

Notwithstanding the resemblance, which this fossil bears to
wood, especially when viewed in detached pieces ; yet the doctor

113

was of opinion, that he was able to prove that it was not of a ve-
getable, but of a mineral origin.

The observations on which he founded this-opinion, will require,
however, here to be mentioned only in a cursory manner. His first
objection is derived from its quantity ; since it extends here to the
depth of seventy feet, and in that of Munden, as we have seen,
they had bored to the depth of fifty feet, without discovering its
bottom : he thinking, that there could have been no imaginable
cause in nature, which could bring together such a mass of fossil
wood, as is found in this and similar strata.

Fossil trees, he remarks, are generally discovered in morasses and
soft ground ; where they have either buried themselves by their own
weight, or been overwhelmed by some accidental cause : but the
Bovey Coal is found in a dry soil, intermixed with clay and sand,
and by its regular course and continuance, he thinks, carries the
most undoubted marks of never having been disturbed since its
original formation. Fossil trees, he likewise observes, preserve
their form and size, their length and roundness, their branches and
roots, their fibrous texture and strength ; and are either found entire,
or in such large pieces, that there is no room to doubt of their na-
ture ; since the very species of wood is frequently distinguishable :
whereas the Bovey Coal comes out only in flat pieces of a few feet
long, like the splinters of large masts ; and on them we discover no
signs of roots, branches, or bark ; no round pieces, nor concentric cir-
cles, which distinguish the annual growth of trees ; the laminae, which
have the appearance of wood, being always horizontal, according
to the situation of the pieces in the strata. Again, he observes, if
the basis or matrix of this fossil were wood, it would acquire, by
being impregnated with bitumen, a greater degree of inflammabi-
lity ; whereas it neither kindles, nor consumes so fast as wood.

The inflammability, and laminated texture, of this fossil, which
have been the circumstances leading to the supposition of its being

VOL. i. Q

114

of vegetable origin,, may be accounted for, in the opinion of Dr.
Milles, from the nature of its principles, and their disposition, when
united, to assume certain forms.

It must not be omitted to remark, that the strata of Bovey ac-
cord very much with those of Munden and Allendorf ; the stratum
of wood, both in Germany and England, being accompanied with
clays, boles, and sand. At Bovey, there also are beds of very
fine pipe-clay, of which great quantities used to be sent to Liver-
pool.

The fossil wood of Iceland, described by Wormius*, appears to
be also of this kind. The surturbrand or sortebrande, accord-
ing to his account, being a laminated substance, generally black,
but sometimes only of a dark brown colour. When first dug out of
the earth, it is capable of being bent like a twig ; but it is brittle,
when dry. It consists of oblique fibres, frequently interrupted by
knots, like the roots of a great tree, which are full of crevices. This
stratum is found, he says, some yards under the earth, in a moun-
tain so high and perpendicular, that those only who have been ac-
customed to climb such precipices, can venture to dig for it. There
is no appearance, that trees ever grew where this fossil is found ;
Wormius, however, concludes them to be roots of trees turned
black, by a subterraneous vitriolic juice.

Horrebow, in his History of Iceland f, describes the sortebrande,
or black-brand, as an extraordinary sort of wood, very hard, heavy
and black, like ebony ; which is found deep in the ground, in broad,
thin, and pretty large pannels, or leaves ; fit for a moderated sized
table. It is, he says, generally wavy and undulated ; and found in
the rocks or great stones, wedged, as it were, close in.

But the most satisfactory account we have had of the fossil wood

of Iceland, is given by Dr. Uno Von Troil, from the observations

i

* Mus. Wormian, lib. ii. cap. 16.

f The Natural History of Iceland, By Horrebow, p. 33.

115

he made during a voyage to that island, with Sir Joseph Banks, Dr.
Solander, and Dr. Lind, in the year 1?72.

The surturbrand, he says, is evidently wood, not quite petrified,
but indurated ; which drops asunder as soon as it comes into the
air, but keeps well in water, and never rots ; it gives a bright,
though weak flame, and a great deal of heat, and yields a sourish,
though not unwholesome smell.

The smiths prefer it to sea-coal, because it does not so soon waste
the iron. The Icelanders make a powder of it, which they make
use of to preserve their clothes from moths : they likewise apply it
externally against the cholic. The doctor says, I have seen tea-
cups, plates, &c. in Copenhagen, made of surturbrand, which takes
a fine polish. It is found in many parts of Iceland, generally in
the mountains, in horizontal beds ; sometimes more than one bed
is to be met with, as in the mountain of Lack, in Bardestrand,
where four strata of surturbrand are found, alternately with differ-
ent kinds of stone.

He brought a large piece of it with him to Sweden, in which
there were evident marks of branches, with the circles of the annual
growth of the wood*.

The same sort of fossil wood is described by Wormius as found
in the island of Faro. It does not, he says, readily take fire,
but has a splendor like jet. It is found in the crevices of the
rocks and is taken out in laminae, or splinters, of three or four
inches thick.

Scheuchzer mentions a stratum of fossil wood, which he saw near
Thun, in Switzerland, which was laying under several strata of flints,
clay, and ash-coloured marie. Of this wood, he says, some parts,
on exposure to the air, grew hard, and others broke to pieces. He
noticed also, that the trunks and branches of this fossil wood
were not round, but compressed; yet, in some places, clothed

* Letters on Iceland, by Dr. Uno Von Troil, D.D. p. 42.

116

with their bark, and here and there adorned with their leaves. The
wood was inflammable, making a strong fire, and serving instead of
fossil coals.

Dr. Plott in his History of Oxfordshire, relates, that the scarcity
of firing, in some parts of that county, has induced the people to
burn a sort of black substance, of a grain somewhat like rotten
wood, half burnt ; partaking also of a mineral nature, and therefore
called by authors metallophyton, or lignum fossile. Put into water,
it will not swim ; and into fire, it consumes but slowly, and sends
forth very unpleasant fumes. A vein of it, at Ducklington, looked
like wood ; yet broken, shewed a smooth and shining superficies,
not unlike to stone pitch ; and put into the fire has not near so ill a
smell. The doctor, who fully believed in the frolics of the stone-
forming archeaeus, says, as to the substance of lignum fossile, it is
thought to be a cretaceous earth, turned to what it is by subterra-
neous heats ; for that it was never formerly wood, notwithstanding
its specious and outward likeness, is plain from its never being
found with roots or boughs, or any other signs of wood *.

Dr. Morton, who likewise did not believe in the subterranean
change and preservation of organized matter, describes two or three
species of this metallophy ton -J- , one of which, he says, is of a dark
colour, and has a grainy for in one direction (which is usually ac-
cording to the length of the pieces) it cleaves or parts pretty readily
into plates and splinters ; the other way it snaps into shorter pieces,
and will not cleave at all. There is another sort, which does not so
readily part into the flakes. None of these are found in any large
masses. They are all, more or less, of a glossy black, and have a
density or smoothness within, like that of bitumen, or jet. In that
also they resemble, as he remarks, the true bitumen, or pisasphal-
ton. They are not so firm and hard as the common coal, and are

* The Natural History of Oxfordshire, by Dr. Plott, p. 65.

t The Natural History of Northamptonshire, by Dr. Morton, p. 121.

nr

much more brittle than cannel coal, or jet. They likewise all of
them agree, pretty nearly, in the same properties. In water they
sink ; they are all inflammable, but consume slowly in the fire ;
emitting a somewhat unpleasant fume, not unlike that of bitumen,
only fainter.

A coal is found in the cliffs, near the castle, in the isle of Port-
land which has been thought to be similar to the coal which we
have been hitherto considering. The Kimeridge Coal, so called
from the place where it is dug, and which appears in most of
the cliffs of the isle of Purbeck, from St. Aldhelm's Chapel to East
Lulworth, and at Ovington, opposite to that part of Portland where
the coal is dug, is also supposed to be of the same kind. But on
reviewing the description of these coals, which are said to be very
hard, and to shiver into pieces like slate, when exposed to the air,
I am more disposed to suspect, that this fossil was rather a bitumi-
nous schistus, than a species of the Bovey Coal.

Hoffman appears to describe a similar species of fossil wood,
found in the neighbourhood of Fischausen, &c. where they dig for
amber. The upper stratum is sand, under it a bed of clay, and
then a woody stratum, consisting of a substance like old wood, but
inflammable ; under this, he says, was a vitriolic mineral ; and lastly
a bed of sand, in which a great quantity of amber was found*.

Of this kind too, very probably, was the fossil wood described by
Caesalpinus, as found in the kingdom of Naples, in a hill near the
city of St. John. Part of this, he says, is formed of an incrusted in-
flammable stone, of a brown or ash colour, resembling decayed
wood. This, he says, the inhabitants employ for their fires. As it
burns it becomes black, like half-burnt wood, and at length passes
into cinders. .

Mr. Fontaine discovered a subterraneous forest, at the bottom
of the chain of mountains between Lyons and Strasburgh. Some

* Observationes Physico-Chem. lib. ii. p. 199.

118

of these pieces of wood still retain their ligneous form, though
actually a vegetable coal.

In the island of Pago, one of the islands in the Adriatic, is a large
internal salt water lake, on the bank of which is a mine of fossil
coal, which is, most probably, .similar to the Bovey Coal. It is
described, by the Abbe Fortis, as still preserving the distinguish-
able appearance of wood ; but being of so bad a quality, that no
use can be made of it except in a case of the greatest necessity *.

Mr. Brand informs us, that Sir Joseph Banks, Bart, and President
of the Royal Society, so eminent for his knowledge in natural history,
favoured him with the inspection of a large specimen of fossil coal,
which is found in Iceland, in strata of considerable thickness, and
at great depths; which seemed to exhibit a substantial proof that
coal originally was wood. Sir Joseph has preserved several trunks
of it, each of which is flattened, possibly by the weight of super-
incumbent strata; so that instead of being cylindrical, as the body
or root of a tree naturally is, it is flat. Some of them are more, and
some less woody ; one is a fair plank of wood. As the woody ones
are thegreatest curiosities, they are sent in preference. The spe-
cimen described, appears to have been the root of a small tree,
with the bark still adhering and remaining on the greatest part of
it. In the lower part, however, the transformation had proceeded
further than at the top, so that it was real coal, while the top was
actual wood-f .

Count Stolberg relates, that bituminous wood may be found
almost every where, at a certain depth, on the western part of
Orange Nassau ; in about 200 fathoms west of which is an immense
quarry of iron stone.

A coal, resembling the Bovey Coal, has also, according tothe

* Travels into Dalmatia, by Abbe Alberto Fortis, p. 503.

t The History and Antiquities of the Town and County of the Town of Newcastle-
upon-Tyne, by John Brand, M.A. H89.

119

account of Mr. Barrow, in his Travels into Southern Africa, been
found at the Cape of Good Hope.

Pillingen informs us, that upon distilling the fossil wood of Meiz-
libizen, he obtained from it, as well as from the bituminous earth,
which accompanied it, nothing which appeared to be derived from
vegetable matter. With a gentle heat, on sand, a water came
over, tasting of bitumen, and a limpid and penetrating oil, like oil
of amber. On increasing the heat, he obtained a more foetid, thick,
and sulphurous oil ; with a slightly acid, but pungently smelling
water. By still farther increasing the heat, he obtained a most
thick, black, stinking oil, with a turbid sulphurous water, having
an acid and disagreeable taste. With an intense naked fire, a light
brown, flocculent, sulphurous, or rather, he says, a saline bitter sub-
limate arose ; leaving a hard clinkery matter at the bottom of the
retort ; from every hundred pounds of which, he assures us, he was
able to obtain nearly an ounce and a half of the purest silver.

Dr. Milles also subjected the Bovey Coal to analysis, by which,
he says, if any doubt could remain of its being a mineral substance,
it must be completely removed.

From one pound of Bovey Coal, of the woody kind, he obtained
on sand, four ounces and a half of water, of a bituminous smell and
taste ; nearly four ounces of a turbid, whitish, bituminous liquor,
of an intolerable foetid smell, and extremely pungent to the tongue;
and about two drachms of a heavy bituminous matter, which would
not mix with the former liquor, but sunk entirely to the bottom,
without leaving any light oil floating on the bituminous liquor.
There remained in the retort about seven ounces of a very black
powder, which had the same bituminous smell, and not very heavy ;
some of which being put on a red hot iron, emitted a little smoke,
but no flame. The ashes of this fossil yielded no salt on being
boiled in water.

120

Salt of hartshorn manifested no particular effect with the water
which first came over ; but with the bituminous liquor, allowed to
stand until it had become clear, it caused a considerable ebullition,
the mixture becoming foul and red ; and in a few days it became
thickened and of the colour of tar, the surface of it, as well as the
sides of the phial, being covered with a bituminous pellicle. By
exposing the black gritty powder, in a retort, to a red heat for two
hours, the neck of the retort became thinly incrustec1 with something
that resembled a saline concrete, but which he found to be only a
bituminous matter.

The black powdery residuum being kept red hot in a close vessel,
for a longer time than he thinks would be sufficient to have reduced
an equal quantity of vegetable charcoal, still emitted a thick heavy
smoke, when sprinkled on a red hot iron ; and upon farther expo-
sure to heat, in an open vessel, an astringent mineral salt was left,
but no other saline matter, which, he thinks, together with the bitu-
minous nature of its products, affords a sufficient proof of this fossil
wood differing from all known wood, belonging to the vegetable
kingdom, and of its being an actual mineral substance.

I cannot close this letter without, in justice to Professor Hollman,
noticing the hard fate of his useful observations, or rather disco-
veries, on this subject. In the year 1753, he delivered to the Royal
Society of Gottingen, a most excellent dissertation on the origin of
marine, and other foreign substances, contained in the earth*;
which appeared in the third volume of the Society's Transactions.
Another dissertation, the one from which we have derived so much
information -f-, was also decreed to appear in the fifth volume of the
same work ; but foreseeing, what actually happened, that the lat-
ter paper would be excluded from public view, in consequence of

* De Corporum marinorum, aliorumque peregrinorum, in Terra continente, Origine.
t Loci memorabilis, in quo ingens Ligni fossilis Copia reperitur, Descriptio.

121

some disputes of a part of the society with the publisher of the
work, he providently resolved to transmit an abridged copy of his
last paper to the Royal Society of London, who did him the justice
to publish it in their Transactions. In the same volume, were
communicated to the public, the remarks on the Bovey Coal, by
Dr. Jeremiah Milles, which I have already so fully noticed ; and in
this paper the opinion of Professor Hollman, respecting the na-
ture of this fossil wood, was, as you have seen, disputed, and its mi-
neral origin asserted. The Professor, however, thoroughly convinced
of the propriety of the opinion he had adopted, sent a paper which
he supposed would confirm the arguments he had employed in his
former paper ; but in consequence, as the Professor supposes, of its
not coming to hand, this paper was never, in any way, noticed.
When he republished his two first papers, at Gottingen, in the year
1784, he, therefore, joined to them two additional papers: one of
which was the paper which had been sent for, but had not appeared
in, the Philosophical Transactions; and in which he fully evinced the
truth and propriety of his former observations ; and the other con-
tained some very judicious remarks on the hypothesis of the gra-
dual change of a cretaceous earth into wood, which had been ad-
vanced by Stelluti ; and by which Dr. Milles had endeavoured to
support his hypothesis of the mineral origin of this fossil wood.

Thus was the first and complete copy of this author's ingenious
paper, on this subject, kept for nearly twenty years from the
eye of the public ; and the abridged copy, governed by a fate
not less severe, made its appearance, under the most unfavourable
auspices ; since, being published in the same volume of the Philo-
sophical Transactions of the Royal Society of London which con-
tained a very laboured attempt at refutation of the very opinion he
had adopted, it appears to have obtained but little notice. The
answer to Dr. Milles's paper, not appearing in the Philosophical
Transactions, it seemed that the Professor, subdued by his superior

VOL. I. R

122

arguments, had left the field to Dr. Milles, and had totally relin-
quished the opinions he had before advanced. Thus the state of the
controversy existed for upwards of twenty years, when Professor
Hollman finding that his paper had not been published in the Phi-
losophical Transactions of London, he published it himself, with
additional arguments, undeniably proving the truth of his first opi-
nions, and the mistake of his opponent.

Injustice to the conductors of the Philosophical Transactions, I
must inform you, that a diligent examination of the papers of the
Royal Society, contained in the library of the British Museum, has
induced me to believe, that Dr. Hollman's paper never came to
hand ; since it is not to be found in its place : nor does there appear
to be any notice of its having been received.

I am pleased to find your last letter dated from Exeter, since it
suggests to me, that by your taking Bovey in your way, you will be
able to obtain for me some account of the Bovey Coal, on the spot.
This, I am confident, you will obtain, by applying to J. Tern pier,
Esq. on whose estate I believe some part of this fossil is plentifully
found.

Yours, &c.

123

LETTER XII.

IN ANSWER, FROM BOVEY.
PRESENT STATE OF THE COAL-PIT AT BOVEY. ...STRATA, &C.

OUR little party are indebted to your letter of introduction to Mr.
Templer, for a considerable degree of pleasure ; and that, notwith-
standing that gentleman was obliged to be absent, in a distant
part of the country, at the time we paid our visit to Bovey, his
polite attention had prepared for us every gratification which the
kindest hospitality could direct : and careful that, notwithstanding
his absence, the object of our visit should be obtained, as com-
pletely as possible, he had requested a neighbouring gentleman to
conduct us to the pit, and furnish us with that information which
you wished to acquire. This gentleman, Robert Scammell, Esq. of
Bovey, with the greatest affability, accompanied us to the spot where
this extraordinary substance is found ; which we found deposited in

layers, to a considerable depth, and extending but it is useless to

give you the observations which I made, since, to secure to you
the most satisfactory account, I prevailed on our obliging and
scientific conductor to supply you with that intelligence, which his
repeated examinations of this spot, made effectual by his scientific
mode of conducting them, must render valuable.

Particulars respecting Bovey Coal, dug at Bovey, near Chudleigh,
Devonshire — by Robert Scammell, Esq. of Bovey.

BOVEY COAL.

THE strata covering the coal, consists of earth of the argillaceous
genus, the argilla apyra of Waller ; the pfeiffen erde of the Ger-

mans. With regard to their depth, a more accurate idea may be
formed from the annexed sketch ; remarking, in this place, the
lower the coal, the less the depth of the incumbent strata. The
depths of the coal strata are various, as will be seen in the following
table, which shows the depth of the several coal beds which are
worked.

Strata.

No. 1

Ft.
1

In.
0

Strata.

No. 11

Ft.

.... 0

In.

fi

2

0

18

12

2

o

3

2

0

13

1

2

4

0

18

14

1

3

i
5

2

0

2

0

o

9

The great bed \

. . . . 1

2

*

in four floors, \

.... 1

4

7

0

4

8

1

0

16 The little bed . . . .

.... 1

0

9

1

0

17 The last bed ....

. . . . 2

7

10 .

. 1

9

The lower coal strata furnish the best and strongest substance
for burning. The shaft, from the grass to the bottom of the last
coal stratum, is seventy-five feet deep. It has been bored thirty-
three feet still deeper, but nothing was discovered but a kind of
muddy clay, intermixed with sand. The disposition of the strata is
displayed by their method of working : they begin on the top, and
clear away to the distance of eight or ten fathoms, and work down,
in a perpendicular direction, through the various strata, to the bot-
tom of the shaft ; then recommence their operations, &c.

The direction of the strata is from north to south ; the inclina-
tion or dip tending to the latter. This inclination is computed to
be about one foot in six ; the leading part is from east to west. The
northern part reaches to the surface, within an hundred yards of the
shaft, where it is cut off by a bed of sand ; to what depth the southern
extremity reaches has not been, and possibly cannot be, ascertain-
ed ; it has been found, however, to extend a quarter of a mile. The

125

eastern portion has been clearly found to extend upwards of seven
miles, by the experiment of repeated boring ; whilst the western has
not, as yet, been traced further than two miles. The whole area, in-
cluding the working, from the first period to the present time,
amounts to ten acres.

The Bovey Coal is now used for supplying the steam-engine, for
burning lime ; and, occasionally, for giving the earthen-ware its first
burning ; it is not now used for domestic purposes, the sulphurous
gas it emits being, not only extremely disagreeable, but injurious
to the health of the inhabitants. It has been said, that exposure
to the influence of the sun and atmosphere, for some months,
deprives it of this pernicious quality ; but this is not warranted by
experience ; even seven years has only lessened, but by no means
destroyed it intirely. It certainly undergoes considerable decom-
position ; the different laminae cracking and peeling off, from the
evaporation of the contained moisture ; it then weighing consi-
derably lighter.

The coal has some peculiarities, with respect to its appearance.'
From this circumstance, the workmen have divided it into three
species or varieties, which they call stone coal, board coal, and knotty
coal. Some portions bear evidently the effect of fire, and resemble,
in every respect, as to external appearance and touch, the common
charcoal.

From every observation and inquiry I have made, it does not ap-
pear, that any substance of a vegetable form has ever been dis-
covered, either in the coal strata or incumbent strata : no leaves,
pine-nuts, or any thing of a similar nature.

Solid bitumen has often been met with, both in the coal and
argillaceous strata; and it has been remarked, that the coal,
taken up after this substance has been found, is always of good
quality. A species of spar, the spath adamantin of the French,

^ been sometimes, though rarely, found in the middle of a por-

tion of the coal. The iron pyrites is met with very frequently.
There are springs impregnated with ferruginous matter, depositing
an ochre, which is sometimes used in the pottery.

It appears, upon enquiry, that the space of time from the Bovey
Coal being first worked, to the present, is a period of upwards of
ninety years. The annexed sketch shows the arrangement of strata.
The white denotes the argillaceous strata, the black points out the
strata from which the coal is procured ; and the lightly shaded are
strata containing an inferior kind of coal, not worth taking up.

OBSERVATIONS.

The spot now worked for the Bovey Coal, is situated in low
boggy ground, which extends several miles: it is said to be the
lowest in the county, but this is an assertion not true. To the
south of the shaft, about a quarter of a mile, is a bog, from which
has been taken (several feet below the surface) many trees of the
fir kind ; several eighteen inches in diameter, together with pine-
nuts, but no traces of coal.

This is the account with which our friendly guide favoured us, and
to us it has proved highly gratifying ; since we have been thereby
enabled to compare the present state of this curious spot, with that
in which it existed near fifty years ago, according to the descrip-
tion given by Dr. Milles. To you, for the same reason, it cannot
but prove particularly acceptable.

Yours, &c.

1 fl'tit

The darkest s/i,i<l,' <l<',,«l<s ////• Mnitn from >'•////•// //"' <<>„/ /..- ///WY//VV/, ////•
////////•..-/. ////' ,m,in<in><ni* Jlr,,l<i .» t/»' intrnne&ale. <m inferior kind of foul.

127

, LETTER XIII.

BITUMENS. ...PARTICULAR KINDS DESCRIBED. ...KNOWN TO WRI-
TERS OF THE HIGHEST ANTIQUITY.. ..HISTORY OF NAPHTHA,
PETROLEUM, AND ASPHALTUM, FROM THE MORE ANCIENT
NATURALISTS.

THE substances, the nature of which next requires our considera-
tion, are those which are generally denominated bitumens. Naphtha,
petroleum, mineral tar, mineral pitch or maltha, asphalt, elastic
bitumen, jet, mineral coal, amber, and mineral tallow, are the diffe-
rent substances which, by general consent, are placed in this class.

The propriety of dwelling on the history of these substances, in
a work devoted to secondary fossils, may not, perhaps, at first sight,
appear; but when their origin is more closely traced, and when
they are considered, in connection with the other substances, which
appear to be derived from the same origin ; not only will their im-
portance be perceived, but their right to be considered, themselves,
as secondary fossils, will, I trust, be evident.

Bitumen is a substance of a peculiar kind, seeming to partake
both of an oily and resinous nature, and is found either buried in,
or proceeding from, different parts of the earth, in different states
of consistence. The different degrees of consistence, as well as the
variety of colour, which the more simple of these substances possess,
according to the valuable observations of Mr. Hatchett, depend
on certain changes, which have taken place in the same substance.
We will first notice the more simple state in which these substances
exist.

NAPHTHA (oleum terra), which Mr. Hatchett considers as bi-

tumen in its greatest purity, is a very thin, yellowish, but some-
times colourless oil, of a strong, but not disagreeable odour. It is
so highly inflammable, that it catches fire, even on the approach of
flame; burning freely, with a large white flame, and leaving
scarcely any residuum. Its specific gravity may be taken at .8475
from Brisson. It does not freeze at 0°". Fahrenheit, It is insolu-
ble in alcohol. By exposure to the air, it becomes yellow, and
then brown ; and at the same time acquires a greater degree of con-
sistency ; passing into petroleum. It is found in great abundance
in Persia; it sometimes is found on the surface of the waters of
springs, and sometimes issuing from certain strata.

PETROLEUM is a tenacious, brown fluid, which, according to the
length of its exposure to the air, increases in thickness, and in dark-
ness of colour ; until it acquires nearly the viscidity of common
tar: its smell, at the same time, becoming less pleasant. In this
state, although highly inflammable, it burns, with a flame less clear
and white, yielding a soot, and leaving a small quantity of coaly
residuum. Specific gravity, .8783, Brisson. It is also found in
Persia, and likewise in many parts of Europe.

MOUNTAIN OR MINERAL TAR is the name given to this sub-
stance, when it has acquired the consistency and colour of common
tar. It emits a strong bituminous smell, on being burnt. Specific
gravity, 1.1.

MINERAL PITCH and MALTHA, are terms employed to mark
the different higher degrees of colour and consistency, which this
substance possesses in its further inspissation. Whilst so soft as to
possess some degree of tenacity, it is called mineral pitch; but when
it has become almost black, and so hard as neither to stain nor ad-
here to the fingers, it is termed maltha. Its specific gravity varies
with its degrees of induration, and with the quantity of earth it
contains.

ASPHALT UM appears to be the same substance, in its highest de-

129

gree of induration. It is a light, brittle, brown or blackish sub-
stance; showing, when broken, a conchoidal fracture, with a glassy
lustre. It manifests a bituminous odour, when rubbed or heated.
It melts easily, and is very inflammable; burning away, when
pure, without leaving any ashes. Its specific gravity, according to
Kir wan, is from 1.0? to 1.65.

Asphaltum has been spoken of by Dioscorides, and other writers
before him, by the name of pissasphaltum; this name, according to
Pliny*, being applied to it, on account of its being mixed with
common pitch. Agricola-f, however, denies this, and contends,
that it derives this name from the circumstance of its odour so
much resembling pitch.

MINERAL CAOUTCHOUC, or ELASTIC BITUMEN, appears to dif-
fer from mineral pitch, merely in the degree of elasticity which it
possesses ; which seems to be the consequence of the confinement
of air, or of some other elastic fluid, in its interstitial cavities.

Having thus furnished you with the most obvious characters of
bitumen in its simpler states, I shall proceed to show you, that at
very remote periods, and in various parts of the world, the peculiar
appearance and properties of bitumen procured it a considerable
degree of attention.

You wrill not only find that it furnished the early writers in na-
tural history with an interesting subject of inquiry, but that it was
known to mankind, as a substance capable of being applied to va-
rious economical uses, in the earliest ages of which we possess any
authentic record.

Noah, we are told, coated over the ark, within and without,
with pitch]:. The builders of the tower of Babel employed some
bituminous matter as a cement ; " they had brick for stone, and slime
had they for mortar §." Of the vessel of bull-rushes, in which Moses

* Lib. xxiv. cap. 1, t De Natura Fossil. lib. iv. p. J95.

% Genesis, chap. vi. ver. 14. § Genesis, chap. xi. ver. 3.

VOL. I. S

130

was exposed on the banks of the Nile, we learn that, " she took for
him an ark of bull rushes, and daubed it with slime and pitch*."

We have perhaps, not sufficient authority, either from the words
which the English translators of the Bible, have here employed, or
from the words adopted into the Hebrew, to rest on more than proba-
bility, that it was bitumen that was used in coating over the ark
of Noah ; or in covering the vessel of bull-rushes, in which Moses
was exposed on the banks of the Nile. Little doubt, however, can
exist, that it was the substance which the builders of the tower of
Babel employed, instead of mortar. In proof of this, we learn^
from some modern travellers, that the remains of buildings have
been discovered, in which bitumen had been thus employed, in-
stead of mortar ; and that there exists every reason to believe, that
this was on the very spot on which Babylon stood.

That this was really the site of the ancient city of Babel, appears to
be very evident, from the information obtained by the learned re-
searches of Major RennelL Abulfeda, he says, an oriental geogra-
pher, states, that the ancient city of Babel has now nothing more
than a village on its site ; and that this village, Hellah, stands on the
land of Babel. This account is very much corroborated by the
Turkish geographer, Ibrahim Effendi, who says, that Babel is close
to Hellali ; and modern travellers agree, that the Arabs, and the in-
habitants on the spot, give the name of Babel to the district round
about Hillah ; and point out vast ruins, as the remains of the ancient
city, spoken of by Abulfeda.

The city of Babylon, in the opinion of Major Rennell, formed
from a careful examination and comparison of the several accounts
given by different authors, must have been at or near the present
city of Hillah, or Hellah, which is known to have been built of the
bricks of the ancient city ; and is even said to stand on a part of its

* Exodus, ehap* iL ver. 3.

131

very site. Herodotus adds, that the fountains of bitumen at Is, from
whence the bitumen used in the construction of Babylon was
brought, were situated at eight days journey above that city : and
as, according to M. Niebuhr, there are copious fountains of bitu-
men near Hit, a town of the Euphrates, one hundred and twenty-
eight German miles above Hillah, reckoning the distance along the
bank of the Euphrates, the learned illustrator of Herodotus thinks
there can be no doubt, therefore, that Hit is the place intended by
Is, which should have been written It.

M. Beauchamp, whose account is translated in the European
Magazine for 1792, says — " the quantity of bitumen that must
have been employed in building Babylon, is scarcely credible.
Most probably," he says, " it was procured from Hit, on the Eu-
phrates, where we still find it. The master mason told me, that he
found some in a spot, which he was digging, about twenty years
ago, which is by no means strange, as it is common enough on the
banks of the Euphrates. I have myself seen it on the road from
Bagdad to Juba, an Arabian village, seated on that river/'

Major Rennel*, to whose information, on this subject, the learned
are so much indebted, remarks, in corroboration of this statement,
that Diodorus says -f, that great quantities of bitumen flow out of the
ground at Babylon ; that these springs supplied it for the building
of the city ; and that it was even used for fuel. Major Rennell is
of opinion, that, perhaps, only such of the public buildings were ce-
mented with bitumen, as were exposed to the weather, or to in-
undations. This agrees with a modern custom in these parts ; for,
on occasion of an inundation, about the year 1733, the walls, in
Bagdad, were covered with a composition, of which bitumen made
a part:£. The cement in the remarkable fortress of Alkadder, in the

* P. 369. t Lib. ii. cap. 1. % Ives's Travels, p, 281,

132

Chaldean desert, according to Mr. Carmichael's description of it,
appears to be bitumen. The wall of Media, which shuts up the
isthmus between the Euphrates and Tigris, above Babylon, was
built of burnt bricks, laid in bitumen * ; and the walls of Perisa bour,
in Babylonia, taken by Julian, were of the same materials f . So
that in those days bitumen was much in use as a cement ; but it
appears to have been disused in succeeding times.

According to Herodotus, a composition of heated bitumen was
used in building, as a cement, in the place of mortar ; being mixed
with the tops of reeds, and placed between every thirtieth course of
bricks J. This account of Herodotus is confirmed by the reports of
modern travellers ; except that some have found the bitumen thus
disposed, at every seventh or eighth course : and M. Beauchamp
found it at every course, in some of the remaining buildings of
Babylon.

From the accounts of various travellers, two different sorts of
bricks appear to have been employed in the supposed buildings of
the ancient city of Babel: the one kind seeming to have been
baked, by fire, and the others, by the heat only of the sun. Some
of these appear to have been deposited in lime and sand, or only in
clay, and others in bitumen : osiers or reeds having been also used>
perhaps, as hair is employed in the mortar of the present day, to.
augment the adhesiveness of the cementing matter.

Having been favoured with some fragments of the bricks, taken
from some ruins near Hillah, accompanied by some of the bitumen..
I was astonished to find that the bitumen, which, from its external
appearance, might have been suspected of having lost all its com-
bustibility, still inflamed* on being brought into contact with the
flame of a candle, and yielded a very strong bituminous smelL

* Xenopbon. An, lib. ii. f Aram. Marc. lib. 24. J i. Clio. c. 178, & seq.

133

Some of these bricks had, on one side, an unknown inscription ; and
on the other, the bitumen adhered ; and, on those parts which were
not covered by bitumen, on the other side, -the marks of matting
appeared, on which it was supposed they had been placed to dry.

From every concurrent testimony, we have, therefore, reason to
conclude, that bitumen was the tenacious substance which the sa-
cred historian meant to describe, as the substitute for mortar, em-
ployed by the builders of the town of Babel. Nor can it be ob-
served, without considerable pleasure, that these discoveries serve
strongly to evince the high degree of fidelity which pervades the
Mosaic history.

Strabo, who speaks of the ruins of Sodom, which, he says,
were sixty furlongs in compass, and were then to be seen on the
shores of the Dead Sea, relates, that the waters of the lake Sirbon
are so heavy in their nature, that those who attempt to dive in
them, are raised up as soon as they sink as low as the navel *. It is
full of bitumen, which rises from the bottom in bubbles, like those of
boiling water, giving to the waved surface of the lake an ap-
pearance as if little hills were arising from it. The bitumen, he
supposes to have been liquified by heat, and then diffused and con-
densed in the water, on which it floats from the peculiar nature of
the water ; and is afterwards obtained by the neighbouring inhabi-
tants, who for this purpose were rowed to it on rafts •)-.

Causabon, Lancisius, in his Notes on Mercatus's Metallotheca,
and others, are of opinion that Strabo has here, by some mistake,
attributed to lake Sirbon, that assemblage of curious circumstances
which more properly belonged to the lake Asphaltin. Indeed his
description, of which a sketch only is here given, corresponds very
nearly, in every particular, with that given by Diodorus Siculus of
the last mentioned lake.

* Strubonis Geogr. lib. xv. f Ibid. lib. xvi.

134

Marcellinus Ammianus states, that the Persians were used to
anoint their arrows with it; and, when lighted, to shoot them i ,to
the roofs of their enemies houses, to set them on fire.

Josephus* describes the lake Asphaltitis, or lake of Sodom;
and particularly mentions no fish being able to live in it, the buoy-
ancy of substances thrown on it, and of large lumps of bituminous
matter floating on it, not unlike the bodies of bulls without heads.
The length of this lake is five hundred and eighty furlongs, the
breadth of it an hundred and fifty. It runs out from the river
Jordan, as far as Zoar, in Africa, and borders upon the land of So-
dom ; where, he says, are yet to be seen the remains of five abomi-
nable cities, that perished in the conflagration produced by a judg-
ment of fire from heaven.

In Samosata, a town of Syria, Pliny relates, there was a pool
which yielded an inflammable substance, called maltha f. Of the
same nature, he observes, is naphtha, which flows in the manner of a
liquid bitumen, and is*found in Austragena, in Parthia £. He also
informs us, that the lake Asphaltitis produces nothing but bitumen,
whence its name. It will not receive into it the bodies of any ani-
mal ; oxen and camels therefore float on it : and hence the report
that nothing sinks in it§.

^lian, Dion Cassius, and other writers, have dwelt with admira-
tion on the wonders of Nymphaeum, on the confines of Appollonia ;
where, they say, there is a pit which is kept filled with bitumen,
which rises from the earth in the same manner as a spring of water.
Not far from thence is a place where continual flames are seen
arising from the earth ; notwithstanding which, the earth is not
burnt, nor do the plants and trees, which grow there, wither from
the effects of the fire ; but flourish and grow to a Considerable
height

* Lestrange's Translation, Wars of the Jews, book v. cap. 4.

t Lib. ii, cap. 104. J Lib. ii. cap. 105. § Lib. v, cap. 16.

135

Bitumen, in this fluid state, has been called by some Latin
writers, oleum vivum. Thus

Vulcano condicta domus, quam subter eunti

Stagna sedent venis oleoque mudentia vivo. — GRATIUS.

Hieronymus observes, that the lake Asphaltitis is called the
Dead Sea, because no animal can live in it : and if any fish, by
chance, come into it, they soon die, and swim on the surface *.

Diodorus, who wrote about forty years before Christ, relates,
that Demetrius, after his battle with Ptolornaeus, formed his camp
on the Asphaltine lake, which, he observes, is highly worthy of de-
scription. He describes it as situated in the middle of the province
of Idumaea, being five hundred stadia in length, and sixty in width.
Its water was so bitter and fetid, that no.fish, nor any other animal,'
could live in it; and, although many rivers of fresh water emptied'
themselves into it, its strong odour was still prevalent. On the mid-
dle of this lake, a mass of solid bitumen arose every year ; some-
times more than three acres, and at other times rather less than one(
acre, in extent. The barbarous inhabitants of the borders of the lake,
named the larger mass, The Bull, and the smaller, The Calf. As the
bitumen swam upon the water, it appeared to those who viewed it
from a distance, to resemble a kind of island. The rising of the
bitumen, he says, is preceded for twenty days by certain peculiar
signs The smell of the bitumen, with an injurious vapour, is dif-
fused to the distance of many stadia around the lake ; and what-
ever articles of gold, silver, or brass are within its influence, lose
their original colour ; which they however regain when all the bitu-
men has exhaled. A neighbouring spot, under which a subterra-
neous fire exists, yields a vapour which smells much more strongly,
and which renders the inhabitants unhealthy and short lived; anjl
to which, perhaps, this change of the surface of metals is more pro*

* Bieronym. in Ezekiel, sec. xlvii.

136

perly attributable. In a valley near to this spot, he observes, the
substance called balsam is found, which is productive of a consi-
derable income ; since in no other part of the world, he remarks, is
this substance to be found, the use of which, as a remedy, is so
very considerable.

Those who inhabit the borders of the lake, adopt a mode, he
says, by which, without the aid of ships, they obtain, and carry
home, the bitumen which floats on the lake. Having tied together
bundles of large reeds, so as to form rafts, three persons, two with
oars, and one armed with a bow and arrows, to repel the inhabi-
tants of the opposite shore, proceed to the floating bitumen.
Having reached the object of their voyage, they get on to the bitu-
men, and load their rafts with pieces, resembling a soft stone, which
they cut from it with hatchets, with which they are purposely pro-
vided. If, whilst thus employed, any one happens to fall into the
lake, our author informs us, that, although not a proficient at swim-
ming, he will not sink, as would be the case in other waters, but
floats as well as the most expert swimmer. The bitumen being
brought ashore, is afterwards carried to Egypt, and sold for the
purpose of embalming the dead : for with this substance, mixed with
various aromatics, they are able to preserve the bodies of the dead
for a considerable time*.

We learn from Agricola-f , that bitumen was collected, in various
parts, in different degrees of thickness, and by different means,
adapted to its consistence and quantity. That it is exceedingly in-
flammable, so that any body being anointed with it, and particularly
with that species of it called naphtha, and having fire applied to it,
would be burnt; water not extinguishing it, unless applied in
great quantity, the flame being best smothered by clay, earth, dust, or
any such dry substances. From its so readily taking fire, it was used,

* Diodori Siculi Bibliothecae Historicae, interprete Laurentio Rhodomano
t De Natura Fossilium, p. 324, edit. Basileae, 1559.

137

in many places, instead of oil, for the supply of lamps. Thus it
was employed in Sicily, being found in the plain of Agrigentum,
whence it was called Sicilian oil. It was also found, he says, near
Soli, in Cilicia ; near Babylon ; at Ecbatania, in JEthiopia ; and in
various parts of India. The common people of Saxony employed it,
Agricola also tells us, not only in their lamps ; but made with it nup-
tial torches, by dipping into it the dried stalks of torch-weed, or
mullein. They also employed it to their carriage-wheels ; to defend
different articles of iron and copper, from rust; and to protect
wooden posts, from the injuries of the weather ; and, for the same
purpose, statues were sometimes covered with it.

Alexander, it is said, for the sake of experiment, set fire to the
naphtha, with which he had ordered the body of a boy to be co-
vered, by which the youth was extremely burnt; so that he must
have perished, if the attendants had not, by pouring over him large
quantities of water, overpowered the flame, and thereby saved
him.

We are informed by Valerius Cordus* that in the plains of
Brunswick, bitumen is dug in a moderately hard state ; and that
there also bitumen, fluid as oil, runs into pits hollowed out for the
purpose; the country people adopting it for the uses already men-
tioned. Bitumen, he observes, is also found in the Alps of Swit-
zerland.

He also relates, that a hard black bitumen is found, most co-
piously, in a certain hill, in the way from Falkenburg to the vil-
lage of Sattela. The best, however, is found about Sattela, and in
the village itself.

Yours, &c.

* Valerii Cordi Observationes quaedam Rerum naturalium variarum, &c. MDLXI.
VOL. I. T

138

LETTER XIV.

ACCOUNT OF BITUMENS CONTINUED, FROM MORE MODERN AU-
THORS....RAY, DOLOMIEU, &C....TAR LAKE IN THE ISLAND OF
TRINIDAD. ...PETROLEUM WELLS IN THE BURMHA DOMINIONS
....RUSSIA, &C.

IN my last I showed you the notice which these substances have
obtained from writers of the highest antiquity : in this, I purpose
to place before you such remarks of more modern writers, as ap-
pear to be most deserving of your attention.

According to the relation of Hasselquist, asphaltum is gathered
by the Arabs, in considerable quantities, every autumn, on the
shore of the Dead Sea. It is carried by them to Damietta, and
there sold ; being employed, he says, in dying wool *.

In the Island of Zante, in the Venetian dominions, there is a
spot, which, on being trod upon, shakes under the feet like a quag-
mire ; in the neighbourhood of this part are springs, which yield a
considerable quantity of bitumen, and particularly, it has been re-
marked, to be affected during the time of earthquakes. It is much
employed, instead of pitch, in paying the bottoms of ships: up-
wards of a hundred barrels in a year being used for this purpose.

At Gabian, about a day's journey from Montpellier, in the way
to Beniers, is a fountain of petroleum. It burns like 'oil, is of a
strong pungent smell, and a blackish colour. It distils out of

•* Hasselquist's Voyages and Travels in the Levant, p. 284.

139

several places of the rock all the year long ; but most in summer-
time. They gather it up with ladles, and put it into a barrel, set on
one end, which hath a spigot just at the bottom: when they have
put in a good quantity they open the spigot, to let out the water ;
and when the oil begins to come, presently stop it. They pay for
the farm of this fountain, about fifty crowns per annum*.

The lake Palius, or Paliorum Lacus, in the valley of Noto, in
Sicily, according to the account of M. Dolomieu, has sometimes
petroleum on the surface of the water: and the mud at the bottom,
and on the bank, which has a black colour, is tenacious, and smells
like pitch. The whole soil of the small plain around it consists of
black, tough, resinous, inflammable earth. A few years ago, some
straw huts in this neighbourhood having been set on fire, the fire
was communicated to the ground, which burnt with a whitish dull
flame, like that of the inflammable springs in Dauphiny, during
several months, and was extinguished with the greatest difficulty ;
as the fire, when extinguished in one place, broke out in another f.

Olearius mentions its being found in Persia J. It is also found
in Norway, in Scotland, in Aquitania, and in Alsace.

The JMumiahi, or Mumia nativa Persiana, as described by Kemp-
fer, in his Amoenitates Persi, proceeds from a rock. The native
place of the best mummy is far from the access of men, from ha-
bitations, and from springs of water, in the province of Daraab.
It is found in a narrow cave, not above two fathoms deep, cut like
a well, out of the mass, and at the foot, of the rugged mountain
Caucasus.

On the south side of a mountain, the northern declivity of which
terminates in the valley of Travers, between Travers and Couvet,
near to Neuenberg, there are two large pits, containingasphaltum;

* Ray's Travels, p. 256 f Magazin sur das neueste aus der Physik, vol. iii.

% Olear. Itin. Pers. lib. vi. c. 9.

140

which, in the year 1?58, had been worked upwards of forty years ;
their produce being sent to different parts of the continent. On
digging at the same height, on the other side of the hill, the same
substance was found*.

Mr. Anderson describes, in the Philosophical Transactions, a re-
markable lake, or rather plain, of bitumen, in the island of Trinidad,
known by the name of the TAR LAKE ; and by the French called
La Bray, from its resemblance to pitch, and its answering the in-
tention of ship-pitching. It lies on the leeward side of the island,
about half way from the Bocas, to the south end, where the man-
grove swamps are interrupted by the sand banks and hills ; on a
point of land which extends into the sea about two miles, exactly
opposite to the high mountains of Paria.

This cape, or headland, is about fifty feet above the middle of
the sea, and has the greatest elevation of land on that side of the
island. From the sea, it appears a mass of black vitrified rocks ;
but, on a close examination, it is found to be a composition of bitu-
minous scoriae, vitrified sand, and earth, cemented together. In
some parts, beds of cinders only are found. In approaching this
cape there is a strong sulphureous smell ; which is prevalent in
many parts of the ground, to the distance of eight or ten miles
from it.

This point of land is about two miles broad ; and, on the east
and west sides, for the distance of about half a mile from the sea,
falls with a gentle declivity to it ; and is joined to the main land,
on the south, by the continuation of the mangrove swamps ; so
that the bituminous plain is on the highest part of it, and only
separated from the sea, by a margin of wood which surrounds it,
and which prevents a distinct prospect of it. Its situation is similar
to a savannah, and, in like manner, is not seen until treading on its

* C. Ludov. TAgascherie du Bl£, Dissertatio Medica sistens Examen Bituminit
Neucomensis, p. 11. H58.

141

verge. Its colour, and even the surface, presents, at first, the
aspect of a lake of water. But Mr. Anderson imagines it obtained
the appellation of lake, when seen in the hot and dry weather :
at which time its surface, to the depth of an inch, is liquid ; and
then, from its cohesive quality, it cannot be walked on.

It is of a circular form, and above three miles in circumference,
appearing at first a plain as smooth as glass ; excepting some small
clumps of shrubs and dwarf trees, that have taken possession of
some spots of it ; but, on a nearer view, it is discovered to be
divided into areolce of different sizes and shapes; the chasms or divi-
sions anastamosing, through every part of it. The surfaces of the
areolce are perfectly horizontal and smooth ; the margins are undu-
lated, and each undulation is enlarged to the bottom, till it joins
the opposite. On the surface, the margin, or first undulation, is
distinct from the opposite, from four to six feet; and the same
depth before they coalesce ; but where the angles of the areolce op-
pose, the chasms or ramifications are wider and deeper. When Mr.
Anderson was there, these chasms .were full of water: the whole
forming one true horizontal plain, which rendered his investigation
of it difficult and tedious; being necessitated to plunge into the
water a great depth, in passing from one areola to another. The
truest idea that can be formed of its surface, would be from the
areolce, and their ramifications, on the back of a turtle. Its more
common consistence and appearance, is that of pit-coal ; but its
colour is rather greyer. It breaks into small fragments, of a similar
appearance and glossy ; with a number of minute and shining par-
ticles interspersed through its substance. It is very friable; and
when liquid, is of a jet black : some parts of the surface are covered
with a thin brittle scoriae, a little elevated. As to its depth, he
could form no idea of it, for in no part could he find a substratum,
of any other substance. Its smell resembled that of pitch, and it.
was so hard, that no impression could be made on its surface,

142

out an axe. At the depth of a foot it was found a little softer,
with an oily appearance, in small cells. A little of it held to a
burning candle made a hissing or crackling noise like nitre, emit-
ting small sparks, with a vivid flame, which extinguished the mo-
ment the candle was removed. A piece, put into the fire, boiled up
a long time, without suffering much diminution. After a considera-
ble exposure to severe heat, the surface burned, and formed a thin
scoria, under which the rest remained liquid. A gentle heat renders
it ductile; hence, when mixed with a little grease, or common pitch,
it is much used for the bottom of ships; for which use it is collected
by many.

It is also found liquid, in many parts of the woods ; and at the
distance of about twenty miles from this, it is found about two
inches thick, in round holes of three or four inches diameter, and
often at cracks or rents. This is constantly liquid, and smells
stronger than when indurated ; and adheres strongly to any thing
it touches : grease being the only thing that will divest the hands
of it. The soil, in general, for some distance round La Bray, is
cinders and burnt earth, and where not so, is a strong argillaceous
soil ; the whole being exceedingly fertile. For thirty miles round,
there is the appearance of the convulsions of nature from subter-
raneous fires ; and, in several parts of the woods, hotr springs are
discovered.

The Abbe Fortis, in his Travels in Dalmatia, describes what he
terms a mine of pissasphaltum, which he saw in the Isle of Bua.
By this mine he means marble strata, more than twenty -five feet per-
pendicular, which sustain the irregular masses that surround the
top of the mountain. From some of these strata tears of pissas-
phaltum ooze out most abundantly, when the sun falls on the mar-
ble rock in the heat of the day. This pissasphaltum he describes
as of the most perfect quality ; black and shining, like the bitumen
judaicum ; very pure, odorous, and cohesive. It comes out almost

liquid, but hardens in large drops when the sun sets. On breaking
many of these drops on the spot, almost every one of them was
found to have an inner cavity full of very clear water. Who can tell,
the Abbe exclaims, whence it came there, or what very remote com-
bustion of woods, or what volcano produced it*? In the valley of
Coccorich, in the Primorte, in Dalmatia, is also a mine of pissas-
phaltum, resembling, in most respects, that of the Isle of Bua-f-.

From the very interesting account of the petroleum wells in the
Burmha dominions, related by Captain Hiram Cox, in the Asiatic
Researches, it appears that the strata of the place in which they are
found, are first a light sandy loam intermixed with fragments of
quartz, flint, &c. — 2dly, A friable sand-stone, easily wrought, with
thin horizontal strata of a concrete of martial ore, talc, and indu-
rated clay. — 3dly, At seventy cubits more and less, from the sur-
face and immediately below the free stone, a pale blue argillaceous
earth (schistus) impregnated with the petroleum, and smelling
strongly of it. This is very difficult to work, and grows harder as
they get deeper, ending in schist or slate, such as is found covering
veins of coal in Europe, &c. Below this schist, at the depth of
about a hundred and thirty cubits, is coal. Captain Cox pro-
cured some, intermixed with sulphur and pyrites, which had been
taken from a well, deepened a few days before, but deemed
amongst them a rarity, the oil in general flowing at a smaller
depth. They were piercing a new well when the Captain was there,
and had got to the depth of eighty cubits, and expected oil at ten
or twenty cubits more. AVhen a well grows dry they deepen it.
They say none are abandoned for barrenness.

The oil is drawn pure from the wells, in the liquid state, as
used, without variation ; but, in the cold season, it congeals in the
open air, and always loses something of its fluidity : the tempe-

* Travels in Dalmatia, by Abbe Alberto Fortis, p. 176. f P. 304.

144

rature of the wells preserving it in a liquid state fit to be drawn. ]
The oil is of a dingy green, and odorous ; it is used for lamps, and
boiled with a little dammer (a resin of the country) ; it is employed
for paying the timbers of houses, the bottoms of boats, &c. which
it preserves from decay and vermin. It is said, that no water ever
percolates through the earth into the wells, that which penetrates
into the earth is effectually prevented from descending to any great
depth by the oleaginous clay and schist ; this will be readily ad-
mitted, when it is known that the coal-mines at Whitby are worked
below the harbour, the roof of the galleries being not more than
fifty feet from the bed of the sea/

From a careful inquiry, the Captain makes the average produce
of each well, per annum, to be seven hundred and ninety-three
hogsheads, of sixty-three gallons each ; and, as there are five hun-
dred and twenty wells registered by government, the gross amount
of the produce of the whole, per annum, is 92,781 tons l,560lbs. or
412,360 hogsheads.

Captain Cox observes, this oil is a genuine petroleum, possessing
all the properties of coal tar; being, he thinks, the self same thing;
the onlv difference is, that nature elaborates in the bowels of the

*

earth that for the Burmhas, for which European nations are obliged
to the ingenuity of Lord Dundonald*.

From the observations of Professor Pallas, as well as from the ac-
counts of Mr. Tooke, it appears that fluid bitumen is found in various
parts of the Russian empire. Naphtha sources are discovered on
the stream Igar, fifteen versts from Sergiefsk, on the Samara, and
others forty versts from it. They yield considerable quantities of
naphtha. On the Terek, in the mountains about the warm springs
at Baragun, near Deulet, Gueray, &c. naphtha and petroleum are
often found; and the sources of Ischelschengisk, are particularly pro-

* Asiatic Researches, vol. vi«

145

lific. There arises- out of holes in the argillaceous and sand-stone soil,
a watery vapour smelling of naphtha, which, collected in pitchers,
is so richly impregnated with naphtha^ but still more with maltha,
that the inhabitants collect both, and use the latter as tar. The
earth hereabouts is all impregnated and black with maltha; on the
shore of the Volga, near Tetyuschy, and near Samarskoy, thick
naphtha oozes out of the stony stratum. On the mountain Irnek,
in the Kirghisian and Khivinschian frontiers, on the road to Orn-
burg, black petroleum flows. A lake on the Sagris, which falls into
the Emba, is covered for a finger thick with naphtha. On the
Sok ; on the Caspian, principally near Baiku ; in Taurida ; in the
district of Perikop, and on the isle of Taman, twenty versts south of
the town of that name ; also at Yenikaly and in the Kuban ; and
on the Baikal, in many places, bitumen is very abundant*.

The petroleum springs of Mount Zibio, near to la Salsa de Sas~
sucolo, in Modena, are, according to the account of the Abb6 Spal-
lanzani-f, highly worthy of notice. The pits, of which there are
two, are dug in a soft sand-stone, the petroleum flowing, with
water, from a narrow opening in the stone and falling into the
water at the bottom, is thence collected, as it swims on the top.
The quantity which has been for ages uniformly yielded in sum-
mer is nearly a pound daily ; but in winter little more than half the
quantity. The petroleum of one of these pits is of a dark yellow
colour, the pit is therefore called bagno nero ; but that of the other
is of a clear yellow, hence the pit is named bagno bianco. This pro-
duct of Mount Zibio had been noticed by Francis Ariosti, as early
as .the year 1460, in a manuscript, since published, and entitled,
Francisci Ariosti de Oleo Montis Zibinii, seu Petroleo Agri Mutinensi$.

* View of the Russian Empire, by Mr. Wm. Tooke, vol. i. p. 249.

f Voyages dans les deux Siciles, &c. par PAbb£ Lazare Spallanzani, torn. v. cap. 43.
The French translation is here referred to, not being in possession of the original, and
this latter* part of the work not having yet appeared in the English language.

VOL. I. U

146

These springs have aslso been noticed by Frassoni, in 1660, in a
pamphlet entitled Thermce Montis Gibii ; by Ramazzini, in 1698 ; and
by Vallisneri, in 1711.

Bituminous substances in various degrees of solidity and purity
are found in several parts of England ; as is indeed the case in most
parts, in the neighbourhood of which coals are found to exist.

Dr. Plott, in a discourse concerning perpetual sepulchral lamps,
read before the Dublin Society, 1684 *, mentions that at Pitchford,
in Shropshire, there is a naphtha or liquid bitumen, that constantly
issues forth with a spring there, and floats upon the water. This,
the Doctor thinks, might be separated, before it joins the water, into
a channel of its own ; and so conveyed to a place thought most con-
venient for such a lamp, into which it should perpetually distil, as
it does now into the fountain. For, the Doctor observes, a brush
or wick of asbestos, or of gold wire, might be employed, and if the
oil be properly disposed, then, says the Doctor, we have an oil as
everlasting as our wick ; nor need we fear any extinction, if en-
closed in a tomb or vault under ground, in never so damp and
moist a place ; it being, he adds, the characteristic of bitumen, to
burn best where there is moisture, as is evident upon affusion of
water upon sea coal.

Among the inflammable minerals of Derbyshire, Mr. Mawes,
whose opportunities of observation are as great, as his collection is
interesting, observes, the most remarkable is the elastic bitumen,
in its various states -j~. It is generally, he says, found between
the stratum of schistus and lime-stone ; rarely in small cavities,
adhering to the gangart, which sometimes contains lead ore, fluor,
&c. When first detached, its taste is very styptic, as if blended
with decomposed pyrites. It varies in colour, from" the blackish
or greenish brown to the light red brown, and is easily compressed ;

•* Mr. Ayscough's C3tal. 4811. Plut. vi. E. vol. i. 34, 1684.

«
t The Mineralogy of Derbyshire, by John Mawes, p. 92,

147

but sometimes the same piece is less elastic in one part than an-
other. On burning it, the smell is rather pleasant.

The varieties of this fossil, described by Mr. Mawes, are — 1.
Elastic bitumen, of a reddish brown colour, containing nodules of
indurated shining black bitumen, resembling jet. — 2. A piece in a
marine shell, in lime-stone. — 3 Dull, red and transparent, in cry-
stallized rluor. — 4. Composed of filaments, like soft cauk, and of a
singular acid taste. — 5. Indurated amorphous masses and globules
of a shining black, like jet ; sometimes liver-coloured ; electric,
when rubbed. — 6. With asphaltum, and containing lead ore; and
the same in long filaments, almost as fine as wire.

A considerable spring of petroleum exists at Colebrook Dale.
Tins spring was discovered at about thirty yards in depth, whilst
digging to form an archway to convey the coals from a very deep
pit. It was at first found to ooze from between the crannies of the
rock, but soon began to pour out in a considerable stream, run-
ning even into the Severn. Large iron pipes are employed for the
conveyance of the fluid into proportionably sized pits, which have
been sunk for its reception. Hence it is conveyed into immense
caldrons, in which it is inspissated, by boiling, to the consistence of
pitch. Whilst fluid, the tar, which appears to be remarkably free
from impurity, has rather an agreeable odour; and when inspissated,
it exactly resembles the asphaltum of the Dead Sea. Since its first
discovery, three different springs of it have broken out, one of
which pours out a considerable quantity. Near to the celebrated
iron bridge, this bituminous fluid is emitted pretty copiously, being
almost pellucid, but thicker than treacle. A similar rock with that
from which the petroleum flows may be traced upwards of seven
miles ; the coals, which are found at some depth beneath, the petro-
leum, are of an exceeding good quality.

From the experiments of Mons. Boulduc*, made on naphtha,

* Histoire FAcadem. Royale des Sciences, 1115, p. 15.

148

learn, that it is so inflammable, that it takes flame before the
flame which is brought towards it is really in contact with it ; that,
when heated in a vessel, it inflames by the flame of a candle held at
a considerable distance above it, a subtile vapour extending some
feet above the fluid ; and that it will burn freely on the surface of
water. He also states, that it is so light as to swim on the surface
of all fluids, even on that of rectified spirits of wine, which is
heavier than it by one-seventh, and does not manifest any action on
it. One drop diffused itself over water to more than the space of
a toise, the water yielding prismatic colours. It mixed perfectly
with the essential oils, particularly with the oils of turpentine, of
thyme, and of lavender. He observed also, that it did not inflame
on the addition of the concentrated acids, but became thickened
on their union with them. A piece of paper soaked with it, soon
became dry, and then, as is the case when spirit of turpentine is
used, ceased to be transparent.

By distillation with a gentle heat, du Ble *, obtained from the as-
phaltum of Neuenberg, a light and limpid oil, which, like naph-
tha, was so subtile, as to evaporate very rapidly in the open air ;
spreading very freely on the surface of water, and taking flame
Very readily. But unlike naphtha, which, according to Boulduc,
will not unite with alcohol, this essential oil entered into union
with alcohol with the same facility as oils of lavender and tur-
pentine.

By properly adapted experiments, he also ascertained, that in
the asphaltum of Neuenberg, both the sulphuric and muriatic acids
existed, in union with calcareous earth.

Fourcroy states, that there is obtained, from brown petroleum,
by distillation, an acid phlegm ; and an oil which at first resembles
naphtha, but which becomes coloured as the distillation proceeds.

* C. Ludov. 1'Agascherie clu Ble, Examen Bitwninis Neocomejisis, 1758.

149

i

There remains in the retort, a thick matter like maltha, and which
may, by further exsiccation, be rendered dry and brittle, like as-
phaltum ; and by a greater or longer continued heat, may be re-
duced to a charcoal.

The alkalies have but little action on petroleum. The sulphuric
acid darkens, thickens, and inflames it ; the same as it does the vo-
latile oils. Petroleum readily dissolves sulphur : it becomes coloured
by the metallic oxides, and unites with amber, which it softens,
and in part, dissolves, by the aid of heat.

Fourcroy obtained from asphaltum, by distillation, an acid phlegm
and a coloured oil, like petroleum. By fusion, he found asphaltum
united intimately with sulphur, phosphorus, the fixed and volatile
oils, resins, gum-resins, and many of the metallic oxides. Alcohol
appeared not to touch it at all ; and ether had an evident, but a
feeble action upon it *.

Yours, &c.

* Systeme de$ Connoissances Chymiques, torn. viii. p. 238.

150

LETTER XV.

AMBER. ...KNOWN TO THE EARLIEST WRITERS IN NATURAL HIS-
TORY.... JET....SUCCINUM NIGRUM OF THE ANC IENTS....CA NNE L
COAL.... DIFFERENCE. BETWEEN IT AND JET.

ASSUMING that the substance treated of in this letter, is a bitu-
minous substance, deriving its origin from the operations of a pe-
culiar process on vegetable matters, which have been long buried
in the earth, I shall introduce its history here, among those of the
purer bitumens ; reserving the examination of the various opinions
respecting its nature and origin, until I have endeavoured to point
out the general principles on which, I presume, changes of this na-
ture depend.

Amber, the electrum of the ancients, is a bituminous, inflammable
substance, of a yellow colour ; varying in its shades of colour, as
well as in its degree of transparency. Its fracture is conchoidal,
and manifests a glassy lustre ; and it is susceptible of a fine polish.
Its specific gravity is 1.078 to 1.085. By friction it yields a pecu-
liar odour, and acquires the property, in a high degree, of attract-
ing to it light substances.

Amber appears to have been known to the earliest writers in na-
tural history. Thales of Miletus was highly interested by its elec-
tric property. Herodotus mentions the places where amber had
been found ; and its peculiar qualities were well known to Aristotle
and to Plato. Philemon classed it among fossils, and distinguished
it into two kinds, the white and the yellow ; which, he relates, were
taken out of two different mines in Scythia. Pliny*, who fre-

* Lib. xxxvii. cap. 3.

. 151

quently mentions it, relates, that the lake Cephisis, near to the At-
lantic sea, and which the Moors call Electrum, yielded, when
heated by the sun, amber, which flowed from its mud.

It is generally found either within the earth, floating on the
waters, or on the sea-shores. In Poland, Prussia, Silesia, Pomerania,
Bohemia, and many other places in that tract of Europe, it is fre-
quently found, when digging to the depth of a few yards. Hermann
relates, that he found amber in an island near the Cape of Good
Hope. It is also found in various parts of Germany, both under-
ground and on the shores, where it has been thrown by the waves
of the sea : but it is found in .the greatest plenty on those shores
which are washed by the waves of the Baltic. It is frequently
found on the sea-shores of several parts of England, most pro-
bably brought by the waves, which have already washed the shores
of those countries, in which this substance so plentifully abounds.
It has also been dug up in detached pieces in several parts of
England. The pits dug for tile-clay, between Tyburn and Ken-
sington, and that pit which was opened behind St. George's hospital,
at Hyde Park Corner, have been said, by Sir John Hill, to have
furnished some very fine specimens.

In the cabinet of the Grand Duke of Tuscany, it is said there is
a column of amber of a beautiful colour and brilliant lustre, ten
feet in height. This, however, is strongly suspected to be only an
artificial imitation of this substance. In the museum of his Ma-
jesty the King of Prussia, is a burning lens made of clear amber,
a foot in diameter. From its yielding to the tools of the artist,
am her is often formed into trinkets of a very pleasing appearance.

The extraneous or adventitious bodies, which are sometimes found
in amber, considerably enhance, by their curiosity, the value of the
specimens in which they are found. In some specimens drops of
water, and in others fragments of gold and silver, have been said to
have been enclosed ; but examination will generally demonstrate, that

152

what has been so supposed are pieces of splendid pyrites. Flies,,
small phalaena, and ants, or parts of these insects, are the foreign
matters which are most commonly thus entombed. From the perfect
state of preservation in which these are found, displaying the sound
appearance and fresh colouring of life, these specimens excite the
highest degree of interest. The position in which these insects are
found, frequently with their limbs separated, as though by strug-
gling to obtain their release, proves that they have been thus en-
gaged and inviscated, by alighting on this substance whilst it was
in a soft state. In the Metallotheca Vaticance, of Mercatus, edited
and brought into public notice by the splendid illustrations of
Lancisius, are excellent representations of various insects thus pre-
served, as well as of some other animals, such as small fishes,
lizards, and frogs, in a similar state of preservation. These latter
have, however, been suspected of being thus involved by some arti-
ficial process, especially as the high price which such rare specimens
would obtain would be a sufficient inducement to such ingenious
exertions. In 'the splendid and elegant work of Sendelius* are
displayed a prodigious number of figures, of specimens of amber,
containing animalculae, insects, &c.

Animals thus, naturally embalmed have furnished the poet, as
might be expected, with an interesting topic. Martial thus ele-
gantly speaks of a viper enclosed in amber :

Flentibus Heliadum ramis dum VIPERA serpit,

Fluxit in obstantem suecina gumma feram ;
dose, dum miratur, pingui se rore teneri,

Concrete riguit vincta repente gelu.
Ne tibi regal i placeas, Cleopatra, sepulcro,

Viperi si tumulo nobiliore jacet. Lib, IV, Epigr. 59.

V <

* Historia Succinorum, Corpora aliena involventium ex regii* Augustorum Cimeliis
Dresdae conditis. Lips. H42.

153

With equal elegance he notices the ant and the bee, entombed
with similar splendour :

Dum Pheathontea FORMICA vagatur in umbra,

Implicuit tenuem succina gutta feram.
Sic, modo quae fuerat vita contempta manente,

Funeribus facta est nunc pretiosa suis. Lib. IV. Epigr. 15.

Et latet, et lucet Pheathontide condita gutta

Ut videatur APIS nectare clausa suo.
Dignum tantorum pretium tulit ilia laborum :

Credibile est ipsam sic voluisse mori. Lib. IV. Epigr. 32.

The celebrated Breynius transmitted, about the year 1665, to the
Royal Society of London, an account of a curious piece of amber
which had fallen under his observation*. This specimen was shewn
to him by an Englishman, a Dantzic merchant, of the name of
Benlows, who valued it at thirty guineas. It was of an oval com-
pressed figure, about two inches and a quarter long, about half that
measure in width, and a quarter of an inch in thickness ; of that
colour, described by Pliny, resembling Falernian wine, and exceed-
ingly fair and clear, not having the least mark from which any sus-
picion of fraud could arise. It contained through its whole length
an extended leaf of the pinnated kind, yielding a beautiful object,
shining with a golden splendour, from the various refractions
and reflections which the rays of light suffered from the surround-
ing medium. The leaf was not perfect, but mutilated at each
extremity, and was formed by five pair of oblong and somewhat
sharp-pointed pinna?, placed at nearly equal distances, and being
in some places evidently eaten. What plant it belonged to he was

* Observatio de succine a Cleba, Plant® cujusdam Folio imprcegnata rarissima. Auc-
tore D«° Jobanne Pbilippo Breynio, M.D. F.R.S.

VOL. I. X

154

however unable to determine, since many different species of this
family are clothed with leaves so nearly resembling each other, as
not to allow the difference in a single frond to be discovered ; espe-
cially when, as in this instance, the surrounding amber prevented
a perfect examination; so that, even with the aid of a magnifying
glass, the veins of the leaf could not be seen. The plant, however,
to which it appears to approach the nearest, is, he thinks, the
securidaca secunda, of Clusius, or the coronilla herbacea, of Tourne-
fort, which is very common in the fields of Prussia. On the one
side of the frond was a small fly, and on the other a spider ; but
neither of them were perceptible without the hqlp of a glass.

In the Metallotheca of Mercatus is also the representation of
what appears to be a small leaf of the coronilla herbacea, flore vario,
of Tournefort, or of the onobrychis secunda, Clusii, which is also
very frequently found in the Prussian fields.

Agricola had observed, two or three hundred years ago, that by
the distillation of amber it was resolved partly into an oil, bearing
a similar colour with amber, and partly into a dark bitumen, which,
he remarks, so much resembles the bitumen of Judaea, as difficultly
to be distinguished from it.

Mons. Bourdelin* relates some experiments which he made with
this substance ; amongst which the most worthy of notice is, that
from two • pounds of amber he obtained only eighteen grains of
earth. He discovered the presence of an acid, which he imagined
to be the muriatic.

It is now known that amber yields by distillation, first an insipid
phlegm, then a weak acid, which in the opinion of Scheele is the
acetous acid, after this a volatile salt arises, and attaches itself to
the sides of the receiver, and the neck of the retort. This salt was
first discovered to be of an acid nature by the Hon. Mr. Boyle, and

* Mem. de 1'Acad. des Sciences, 1743,

155

it has since been ascertained to be a peculiar acid, differing in some
of its chymical properties, and in its affinities, from other acids.
If the distillation be continued, the fire being augmented after the
succinic acid is come over, a thick brown oil, which yields an acid
taste, will be then distilled. But if water be employed in the dis-
tillation, a clear light oil will come over, which darkens by keeping,
first becoming of a yellow, and then, by degrees, even of a dark
brown colour.

JET is a compact, opaque, and very black substance, of almost
a stony hardness ; capable of receiving a high polish, and breaking
with a conchoidal fracture, and a glassy lustre. Its specific gravity
is 1.259. On being rubbed it manifests electric attraction ; when
heated it yields an odour resembling that of asphaltum, but not so
powerful ; and when inflamed, by a strong heat, it burns away,
leaving an earthy residuum. It yields by distillation a bituminous
oil, and an acid, which seems to resemble that of amber.

The term succinum nigrum, or black amber, has been applied by
several ancient writers to this substance; and indeed with much
propriety, it seeming to be the bituminous substance next in purity
to amber, and approaching the nearest to it in its several pro-
perties. It may be considered as possessing the intermediate place
between the purer bituminous matters and coals, it holding a suffi-
cient quantity of charcoal to give it blackness ; but has not suffered
that kind of change which serves to correct the disagreeable odour
which the less altered bitumens yield on the application of heat.

Although the surface of jet sometimes bears a striated and lig-
neous appearance, its conchoidal fracture evinces that closeness
i)f structure which does not determine its separation, in any one
particular direction more than another. Plence it is employed
to form various trinkets, such as beads, buttons, &c. it yielding
pretty readily to a careful application of the instruments of the
turner.

156

Some are of opinion that the hard bitumen spoken of by Xeno*
crates, and the substance described by Theophrastus as found in
the silver mines of Scaptesyla, and which I have already referred
to Bovey coal, was jet. Strabo* speaks of jet, found in Mesopo-
tamia, as possessing the power of driving away serpents. It is evi-
dently the same substance as was described by Nicander, as the
Thracian stone ; and which was named by Dioscorides, gagas or
gangas, from its being found near the city of Ganges. Pliny, who
in speaking of jet, in another place f, confounds it with aetites,
owing to both these kinds of stones being found in the nests of
eagles, says that it derives its name from the river Gagis in Lycia,
and that it is thrown up by the waves in Leucola. It is, he
says, smooth, brittle, light, and porous, not differing much in ap-
pearance from wood, and yielding a strong odour when rubbed. It
also appears to be this substance to which Pliny refers :£, when he
says, the island of Samothracia yields a black and light gem, resem-
bling wood, which, deriving its name from that of the place, was
called the Samothracian gem. Agricola § informs us of many places
in which it is found, and is of opinion that Pliny meant this sub-
stance, when speaking of the obsidian stone. But the description of
Pliny, which is indeed most applicable to the obsidian of the present
day, can never be admitted to apply to jet. The words of Pliny ||
are, " In genere vitri et obsidiana numerantur, ad similitudinem
lapidis, quern in Ethiopia invenit Obsidius, nigerrimi colons, ali-
quando et translucidi, crassiore visu, atque in speculis parietum
pro imagine umbras redden te. Gemmas multi ex eofaciunt: vidi-
musque etsolidas imagines divi Augusti, capti materia hujus crassi-
tudinis: dicavitque ipse pro miraculo in templo Concordiae obsi-
dianos quatuor elephantos."

* Strabon. Georg. lib. xvi. f Lib. x. c. 3. $ Lib. xxxvii. c. 10.

§ Lib. xxxvi.c. 19. || Lib. xxxvi. c. 26.

157

This substance is thus spoken of by Marbodeus*:

Nascitur in Lycia lapis, et pvope gemma gagates,
Sed genus eximium foecunda Britannia mittit,
Lucidus et niger est, et levissimus idem,
Vicinas paleastrahit attritu calefactus,
Ardetaqua lotus, restiiiguiturunctus olivo,

It is frequently found, as. was known to Solinus, in various parts ,
of this kingdom. It is very abundant in the neighbourhood of
Liege, and particularly so in, a celebrated mountain of coal, in
Misena, not far from the city of Zuicca. It is also found in various
parts of Spain, France, and Germany, and indeed in almost every
part of the known world.

It is most frequently found in the neighbourhood of coal mines,
and in detached pieces, on the sea shores, in various subterranean
situations, and frequently in strata which are evidently alluvial. I
have found it in the blue tile clay, beneath, the gravel, at the depth
of twenty feet, in the gravelr-pits near Hackney ; in pieces about
one or two inches square, having pyrites adhering to them, and
bearing on one side of them the striated structure of wood. ,

CANNEL COAL seems to be the bituminous substance next in
purity to jet. It is a black, opaque, compacjt, and brittle sub-
stance : it breaks with a copcfroidal fracture. Its specific gravity
varies from 1.232 to 1.426. It does not soil the fingers. It kindles
very easily, and burns with a bright white flanie, like that of a v
candle, leaving an earthy residuum, and not caking into a cinder.

By the analysis of Mr. Kirwan, its composition is 75-2Q of
charcoal^ 21.618 of bitumen, and 3.10 of aluminous and silicious
earths.

Like jet it possesses tha,t, compactness of structure which renders
it susceptible of polish, and capable of being wrought into trinkets
of various, forms. The chief differences between jet and Cannel

* Dactylotheca Marbodei Galli : cum Scheliis Gforgii Pictoris. Basileae, 1531,

158

coal appear to be, that jet is found in detached masses, whilst
Cannel coal is deposited in strata ; and that jet, once set on fire,
continues to flame for a considerable time, a bituminous vapour
being at the same time exhaled ; whilst Cannel coal requires to be
so disposed, that its combustion may be aided by that of the sur-
rounding fire, and by an increased rapidity of the accession of air.
The difference between the chemical phenomena yielded by this
substance and by jet appears to depend chiefly on the greater quan**
tity of earth which enters, as a constituent part, into the composi-
tion of Cannel coal than into that of jet. The terra ampelitis of the
ancients has been supposed by many to have been the substance
we are here treating of; but the term seems, most generally, to have
been applied to that species of loose bituminous earth which exists
in those parts, in which fluid bitumens have prevailed.

The coal possessing these properties, and which is obtained from
Lancashire, is that to which the term Cannel coal is most com-
monly applied ; Cannel coal being the provincial expression for
Candle coal; candle in the Lancashire dialect being pronounced
cannel ; the high degree of inflammability possessed by this sub-
stance having obtained for it this distinction. The coal called
Scotch coal, from its being obtained from Scotland, possesses similar
properties. It is obtained in large solid compact masses, and con-
tains nearly as large a proportion of bitumen ; it flames almost as
freely as the former, and burns away to a white ash.

The Cannel coal of Wigan in Lancashire, the most beautiful coal
of this species, is found, according to Mr. Godefroy de Villetaneuse,
at the depth of seventy-six yards from the surface of the rock ; over
which is a stratum of earth, from three to eight yards in thickness.
The first stratum of the rock, he states, to be two feet in thickness ;
laying on a metallic stone of a deep blue colour, forty-six yards
thick. Underneath this is a vein of common coal, five feet in thick-
ness ; and thirty yards beneath this is found the Cannel coal, the
thickness of which is one yard two inches.

159

Pits of similar coal have also been dug in Cheshire, and in some
other parts of the kingdom.

Dr. Plott relates* that the Cannel coal from Wednesbury Common
Pit is of so close a texture, that it will take a passable polish ; as
may be seen in the choir of the cathedral church of Litchfield,
which in great part is paved in lozenges, black and white, as other
churches with marble ; with Cannel coal for the black, and alabaster
for the white. He also says, that " at Beaudesart will work so very
fine, that the king's majesty's head is said to have been cut in it,
by a carver at Litchfield, resembling him very well."

Yours, &c.:

LETTER XVI.

COAL DESCRIBED.. ..DIFFERENT KINDS OF COAL.... DOUBTFUL IF
KNOWN TO THE GREEKS, OR EARLY ROMANS. ...BROUGHT INTO
COMMON USE, IN THIS ISLAND* BUT IN MODERN TIMES.-,.
FOUND IN VARIOUS PARTS OF THE WORLD.

A WAS much entertained by reading the acccount of your subterra-
nean incursion ; and have frequently since smiled at the ludicrous
appearance which you, and our friend Wilton, must have made,
dressed in a collier's garb, and descending, by a bucket, down the
shaft of a coal pit. The astonishment with which you were stricken
on your entrance into the pit, is forcibly expressed, by your saying,

* The Natural History of Staffordshire, by Dr. Plott, p. 125,

160

that it seemed as if you had discovered another world, just beneath
the crust of that which you had lately quitted. There can undoubt-
edly be hardly any scene, which can be presented to the view,
capable of exciting more astonishment than the one you describe.

Wonderful indeed must have been the scene^ after a dark and
dreary descent through so many fathoms of dripping strata, which
•must have offered itself, when you made your entrance into a cavern
from which the glimpse of day was excluded ; where the roof, the
floor, and the walls, presented every where to the eye the same
jetty black ; except where the oozing drop, or the brilliant spar or
marcasite, reflected the flames of the lamps; which, disposed in
various parts, lighted the inhabitants of these seeming Vulcanian
regions to their labours. These, as you inform me, were separating,
with their ponderous instruments, into fragments of a convenient
size, parts of the immense mass of coal, which years and years of
labour had seemed to have left inexhaustible. Such an assemblage
of striking and entirely novel appearances could not fail of exciting
a train of thoughts widely different from any your mind had yet
known, and must necessarily have rendered you anxious to gain
some information as to the history of these regions, This part, as
well as the rest, of my engagement, I shall perform with the utmost
readiness, pleased with the idea that I may thus render your de-
lightful tour more interesting and instructive.

Common coal, that substance so eminent for its utility to man as
an article of fuel, is the fossil which therefore shall next claim OUT
attention.

COAL is a black, solid, and compact substance, generally of a
foliated or rather laminated structure, which necessarily directs its
fracture. Its specific gravity is 1.25 to 1.37. It possesses a mode-
rate degree of hardness, but is more brittle than Cannel coal; than
which it also takes fire less readily, and is longer in consuming. It
cakes into cinders mare or less during its combustion* according to

161

its degree of purity and the nature of the earths which enter into
its composition. It has obtained various names, derived from cer-
tain varieties of its appearance, nature, &c. Thus, from its pitch-
like colour and fracture, it has been sometimes called pitch coal ;
from the great degree of hardness which it sometimes possesses,
stone coal; from its being obtained from a mine or pit, pit coal;
and in London, for no better reason than its having been brought
hither by sea, sea coal.

There are certain varieties of pit coal, which obtain their parti
cular denominations from their mode of burning, or from then
most obvious and predominant combinations. Hence we have
blind or deaf coal ; such is the Welsh and Kilkenny coal, kindling
slowly and burning without flame or smoke to a stony flag. Open-
burning coal, which does not cake, but burns with much flame and
smoke, and is soon reduced to ashes. Close-burning coal, which
kindles quickly, and melts and runs together like bitumen. Some
coal is termed slaty coal, from its texture ; and when it also contains
a larger proportion of bitumen it is called slaty Cannel coal. Culm is
a coal in small rough fragments, which does not melt or cake, but
leaves behind it a slag of the same bulk with the coal employed,
which yields a large portion of ashes, formed by argillaceous earth
impregnated with iron.

If the translation of Sir John Hill * be admitted, and his argu-
ments in support of it undoubtedly appear to be forcible, fossil
coal was known in the time of Theophrastus. The passage is,
" Those fossil substances that are called coals (a^axaf), and are
broken for use, are earthy ; they kindle, however, and burn like
wood coals (avdfaxe;). These are found in Liguria, where there is
also amber, and in Elis, in the way to Olympias over the moun-
tains. These are used by the smiths/'

* Theophrastus's History of Stones, translated by Sir John Hill, p. 63.
VOL. I. Y

162

He contends, that the meaning of Theophrastus is evidently,
that they kindle and burn like wood coals, or, as we call it, charcoal ;
that being, he remarks, the genuine and determinate sense of the
word avQpot% in the other works of this author, in those of Pliny,
and of all the other old naturalists. Even the more correct of the
moderns, when they would express what we call pit coal, the sub-
stance which he contends is here described by this author, never
use the words «v0pa£ or carbo alone, but always carbo-fossilis, and

Another passage of the same author seems also evidently to ap-
ply to coals : he relates, that some of the more brittle stones become
as it were burning coals, when put into fire, and continue so a long
time. Of this kind are those about Bena, a town in Thracia ; found
in mines, and washed down by the torrents ; for they will take fire
on throwing burning coals on them, and continue burning so long
as any one blows on them; afterwards they will deaden, and may
after that be made to burn again : they are therefore of long conti-
nuance, but their smell is troublesome and disagreeable *.

Unless it be admitted that coals were known to Theophrastus,
according to the opinion of Sir John Hill, we may, I believe,
assert, that we have no proof of their having been known to the
Greeks, or to the early Romans. The Latin does not even possess
a name for this substance. Nor indeed is it to be wondered at
that they should be thus ignorant of it, if, as is observed by the
learned writers of the Encyclopaedia Britannica, there are, in fact,
no beds of it in the compass of Italy : the great line of that fuel
seeming to sweep away round the globe, from north-east to south-
west ; not ranging at a distance even from the south-easterly parts
of our island, as is generally imagined, but actually visiting Bra-
bant and France, and yet avoiding Italy. It has been inferred

* Theophrastus on Stones, p. 53.

163

from the circumstance of Caesar's not having spoken of this sub-
stance, whilst describing this island and its productions, that coal
had not then been discovered by the Britons. But, according to
Whitaker, pieces of coal, with a quantity of slack, were dug up
under the Roman way to Ribchester ; and the same writer observes,
that in the West Riding of Yorkshire, and particularly in the neigh-
bourhood of North Brierley, several large heaps of cinders have
been found, which he supposes to have been deposited there by the
Romans: a conjecture rendered probable by a number ofRoman
coins having been found in one of these mounds. Horseley, in his
Britannia Romana, remarks, that there was a colliery not far from
Brierley, which, in the judgment of those who are best capable of
determining on such a point, appears to have been wrought by the
Romans. Wallis, in his History of Northumberland *, says, that
the Romans were as well acquainted with our pit coal, as with our ores
and metals. In digging up some of the foundations of the Roman
walled city Magna, or Caervorran, in 1762, coal cinders, and some
very large, were turned up. Mr. Pennant also observes, that a flint
axe, used by the aborigines of our island, was discovered stuck in
certain veins of coal exposed to the day in Craig y Pare, Mon-
mouthshire; and in such a situation as to render it very accessible
to unexperienced natives, who in early times were incapable of
pursuing the veins to any great depth.

Excuse me if I have been rather tedious, in thus producing au-
thorities in proof of this commodity having been known and used by
the primaeval Britons. Remember that I am treating of that, which,
from the great abundance in which it exists in this island, and from -
its superior quality, adds in a direct manner to the number of our
comforts ; and also gives indirectly to the country many peculiar and
important advantages. This substance was not brought into common

* Vol.i. p. ii».

164

use, in this part of the British empire, until the reign of Charles the
First ; and even in Scotland, almost proverbially poor in vegetable,
and rich in fossil fuel, it was at a very late period that coal was
commonly used ; for about the middle of the fifteenth century,
when uEneas Sylvius visited this island, he saw in Scotland poor
people, in rags, begging at the churches, and receiving for alms
pieces of stone, with which they went away contented. This spe-
cies of stone, he says, whether impregnated with sulphur, or what-
ever other inflammable substance it may be, they burn in place of
wood, of which their country is destitute*.

Mr. Arnotsaysf, " Coal certainly was not discovered in the mid-
dle of the twelfth century, and it was as certainly known in the be-
ginning of the thirteenth century. In the Leges Burgorum^:, which
were enacted about A.D. 1146, a particular privilege is granted to
those who bring fuel into boroughs. Wood, turf, and peat, are
particularly mentioned, but with respect to coal there is a dead
silence. But in the year 1234, Henry III. of England renewed a
charter which his father had given to the inhabitants of Newcastle ;
and in this renovated charter he grants, upon their supplication, to
the persons in whose favour the charter was conceived, licence to
dig coal upon payment of ^.100 a year, which is the earliest
mention of coal in the island/' And Boetius||, in his Description
of Scotland, his native country, written in the beginning of the six-
teenth century, says, " There are black stones also digged out
of the ground, which are very good for firing ; and such is their
intolerable heat, that they resolve and melt iron, and therefore
are very profitable for smiths and such artificers as deal with other
metals/'

In most countries of Europe has this valuable substance been

* jEneas Sylvii Opera, p. 443. t History of Edinburgh.

$ Leg. Burg. c. 38. || Boetii Scotorum Regni Descriptio, p. 10.

165

found. Coal has been dug in France, Germany, and Sweden ; and
especially at Liege there are very considerable coal mines : but the
mines of this island exceed, both in quality and extent, any that
have yet been discovered. In Wales, coal is found almost through
the whole principality. Ireland is also very far from being deficient
in coal mines; although they have not yet been found in such
abundance as in other parts of the United Kingdom.

It has been found on the other side of the Atlantic ocean, in
Newfoundland, Cape Breton, Canada, and some of the New Eng-
land provinces. Mr. Jefferson informs us, in his Notes on Virginia*,
that the country on James river, from fifteen to twenty rniles north-
ward and southward, is replete with mineral coal of a very excel-
lent quality. In the western country, he says, coal is known to be
in so many places, as to have induced an opinion, that the whole of
the tract between the Laurel mountain, Mississippi, and Ohio, yields
coal. It is also known in many places on the north side of the
Ohio. The coal of Pittsburg is of very superior quality. Dr. An-
derson*)- states, that coals have been discovered also at Madagascar.
At the Cape of Good Hope, where fuel is very scarce, we learn, by
the accounts of Mr. Barrow :£, that coal has been lately discovered
coming out to day, at the depth of two feet, along the banks of a
deep rivulet flowing out of the Tygerberg hill.

In China, it is probable that coal was discovered long before it
was known in the western world. About the middle of the thir-
teenth century, a noble Venetian, in his description of China, ob-
serves, " That through the whole province of Cathay, certain black
stones are dug out of the mountains, which, being put in the fire,
burn like wood, and when kindled, they continue burning a long

r Notes on the State of Virginia, by Thomas Jefferson. London, L787, p. 43.
t Anderson's Dictionary of Commerce, vol i. p. 229.
I Travels in Southern Africa, by Capt. Barrow.

166

time, insomuch that if they are lighted in the evening the fire will
keep alive during the whole night*."

COAL is found at various depths in the earth, and interposed
between strata of different kinds. The veins of coal also vary con-
siderably in the thickness of the vein; sometimes being many yards
thick, and other times being merely a seam, little more than an
inch in thickness.

The strata, which are generally interposed between the gravel,
clay, sand, and mould, at the surface, and the coal itself; or which
appear to be most generally connected with coal, have commonly
a considerable degree of hardness : but they differ from each other
very much in this respect, as well as in their thickness and their
other properties. Do not fear that, by endeavouring to-furnish you
with some information respecting these several strata, I shall engross
your time with the consideration of matters irrelevant to the grand
object of our inquiry ; on the contrary, be assured that it will de-
rive from this investigation a considerable degree of illustration.

SAND-STONE is among the uppermost of the solid strata. It is
of a granulated substance, of various degrees of hardness and co-
herence ; and is formed by^ very small grains of various silicious
stones, and frequently of mica, imbedded in a calcareous argilla-
ceous, or even a silicious cement. In the latter instance they pos-
sess a great degree of hardness ; the hardness is also considerably
increased, in every species, by the admixture of iron which has
undergone but a slight degree of oxydation.

RUBBLE-STONE is a species of sand-stone, containing also a bluish
slaty substance.

LIME-STONE also frequently occurs among the superior solid
strata, and like the former is also found among the inferior strata.
It exists in very considerable varieties of hardness and coherence,
breaking with various kinds of fracture, according to the sub-

* Marcus Paulus Venetus. Purchas's Pilgrimage, vol. iii. p. 88.

16?

tances which unite with the calcareous matter of which it is chiefly
formed.

FREE-STONE, so called from its breaking on working in all direc-
tions with the same degree of freedom, is a compact lime-stone
of an earthy fracture, and is often met with in the search for coal.
When it is of a very considerable degree of thickness, it obtains, in
many coal countries, the name of post-stone, of which four varieties
occur, named, according to their colour, white, grey, brown or yellow,
and red post. These are sometimes called by the colliers bands ;
thus they will say grey free-stone bands, but the Scotch colliers term
them grey f ekes.

WHIN-STONE, BASALTES, and other stones whose hardness is
such that their angular parts will scratch glass, and whose fracture
exhibits an appearance so much resembling that which might be
expected from sand half vitrified, as to have induced many to
suspect them to be of volcanic origin, also form strata of con-
siderable importance, from their hardness and quantity, in most
coal mines. These are commonly called cockle in Cornwall, and
skurdy in the north of Scotland.

IRON-STONX, called also metal-stone, and by the Scotch colliers
dogger band, is a stratum, which is generally next above the roof
of the coal. It is very hard, compact, and solid, and of considerable
weight. Its colours are various shades of brown and grey, and
sometimes it is nearly black. It evidently consists of argillaceous
earth impregnated with iron. Nodules of a richer ore of the same
metal are frequently contained in it. These are called ball iron-
stone, cat's-head, and doggers. Masses of pyrites are also frequently
found in this stratum.

SHALE, or slate-clay, called also shiver, black metal, and bleas,
and by the northern colliers blae or till, often also forms the roof of
coal mines. It is generally bluish, blackish, or of a reddish grey.
It is frequently marked with impressions of vegetables, It breaks
into long thin shivery lamina, and is very friable. It readily re-

168

solves, on being immersed in water, or even on exposure to the air,
into a fine soft clay. It contains a portion of bituminous matter,
and generally has an unctuous feel, on which account the Scotch
colliers term it creeshy blaes or greasy blaes.

Not only do these strata vary in different districts, but, even in the
same district, a considerable difference will sometimes be found in
the strata ; and these differences may even arise from varieties fre-
quently occuring in the same species of strata, from which may result
several distinct strata, differing in colour, quantity, coherence, &c.
whilst a stratum of another kind may occur only once or twice.

The following Example of the different Strata of Earth, Stone, and Coal, in a Coal Mine
to the West of Dudley, in the County of Stafford, will serve to give you an idea of the
manner in which they occur.

Strata. Ft.

No. I Yellowish clay, immediately under the mould 4

2 Bluish clay 5

3 — more compact and firm, called clunch, and bearing the impression of plants . 24

4 softer than No. 3 9

5 A bank (stratum) of grey stone 4

6 Whitish yellow clay 21

7 Hard grey rock, with faint impressions of vegetables 75

8 Clunch, in which fossil plants are found 5

9 Bench or bank coal (black and glistening) 1

10 Slipper coal (abounding with coals) 3

11 Spin coal (a blacker and glossy coal) 4

12 Stone coal (pretty like Cannelcoal) 4

These four beds were separated by BATS, a hard stony earth 1

13 Dunrowbats j •

14 Grey iron-stone, called grey-bench 0 1

15 Bluish bat, in which is found iron-stone 0 3

16 Blackish and hard iron ore, called white-row grains, the grains being like shot I 3

1 7 Hard grey iron mine, spotted with white, called mid-row grains 0 2

1 8 Gubliu bat, a black fissile substance, an iron ore, in which a bituminous shivery earth

abounds 0 2

] 9 Gublin iron-stone (an iron ore, hard, blackish, and spotted with white) 0 9

20 Bat, lesembling No. 18 1 6

21 Canuoc iron-stone, hard and grey 0 6

22 Bat, somewhat harder than No. 20 1 0

23 Rubble iron-stone, in grains, grey and hard 0 6

24 Table bat 2 0

25 Foot coal, a coarse sort 1 0

26* Bat, black, brittle, and glistening 6 0

27 Heathencoal 6 0

28 Bat coal, an ordinary coal, in a thin bed, and doesjot bum well 0 i

29 Bench coal 2 0

30 Bat 0 6

180 6

169

In the foregoing table are several terms, which, being provincial
expressions, may not be generally comprehended. They will, how-
ever, be understood, probably, sufficiently well for the present in-
tention : it, however, may not be amiss to observe that clunch, in
that part of the country to which the above table refers, represents
the firm blue clay of Wallerius (argilla plastica particulis subtiliori-
bus), which is generally used for tiles: and in Cambridgeshire the
same term is employed to describe a white hard clay, containing

sand and small stones. *.

/

The line formed by the bearing, or laying of one stratum upon
another, is termed THE PARTING, and according to the facility of
separation it is named a good parting or a bad parting. Sometimes
the two strata are so closely conjoined as to render their separation
very difficult, this is termed a bad parting. On the other hand, a
thin dusky laminated matter is sometimes interposed between the
two masses, whereby a good parting is formed.

Besides these partings of one stratum of coal from another, each
stratum will be found disposed to part, at numerous secondary di-
visions er partings, which run parallel to the former, but are neces-
sarily not so visible nor so strong. Other divisions or lines of
separation occur, which cross the former horizontal ones in nearly
a perpendicular direction ; these are called BACKS. These are crossed
too by others, at right angles, also in a direction approaching to
perpendicular: these are called CUTTERS. The facility of separa-
tion at these lesser lines of partings will often be found to be pro-
moted by a film of pyritous, earthy, and even stony matter having
formed the substance which is interposed at these partings.

In the parting between the superior part of the mass of coal,
and the impending stratum or roof of the mine, very considerable
differences occur. Sometimes the parting is very difficult and bad,
from the closeness of their union. At other times the head of the
mass is sprinkled with a powder like soot, or powdered charcoal

VOL. i. z

170

Sometimes the separation is perfectly easy and clean, owing to the
smoothness of surface possessed by the head of the mass, which
appears with a brilliant polished surface, as if it had been covered
with a varnish or some matter which had been in a liquid state.

Sometimes, as is observed by Mr. Williams, to whose excellent
work, on the subject of coal I acknowledge myself much indebted,
the roof, as it is called by the English, and the crop, as it is called
by the Scotch colliers, falls down for a certain space below its ordi-
nary level, and presses the coal, or squeezes it much thinner, espe-
cially in the middle of that space. These accidents of the roof
pressing down nearer than it should be to the pavement, as the
bottom is called, and squeezing the coal in that part to less than
its ordinary thickness, exist in very different dimensions. Some-
times it thus presses down, and cuts off the thickness of the coal
to the extent of several fathoms. Sometimes these depressions are
not above two or three feet in diameter, when they are called, by
the Scotch colliers, a bonnet-case, or pot-arse. But all these ac-
cidents are not of such small dimensions as the bonnet-case : some
of them are not only two or three feet, but two or three yards in
diameter, and sometimes even thirty or forty yards and more.

The stratum of coal is seldom so regular and good near the sur-
face of the ground ; whereas th£ seams of coal which are lower
down, as well as the strata which accompany them, have much
more firmness and compactness, and also manifest more regularity
of stratification.

Frequently the strata, instead of being continued in a regular
horizontal direction, have their lines broken and disordered 03^
fissures and breaks. These are generally termed SLIPS, and very
frequently will be found to have thrown the coal a considerable
way out of its regular course. Sometimes the strata will be found
to have slipped down, on one side of the breach, a considerable
number of feet ; perhaps many fathoms : and sometimes it will* be

171

found that they will be thrown up again as much by one slip, as
they appear to have been thrown down by the other. It sometimes
happens that all the slips are down-slips, the strata seeming to have
sunk lower in each succeeding slip. These slips differ very much
in their width, as well as in the matter with which they appear to
have been filled. Some, which are wide, are filled with adventi-
tious and heterogeneous matters ; and others with soft argillaceous
substances. Other slips are seen, in which, although the strata are
thrown a great many fathoms off the ordinary level, the two sides
of the fissure are found, in some places, quite close together. In
these perpendicular fissures, or rake veins, as they are called by
miners, a confused mass of heterogeneous matter, solid whin-stone,
spar, ores, and metals, and particularly sulphurets of metals, are
frequently found ; very large ribs of spar, and of pyrites, being
very frequently thus disposed. A DYKE is a separation or chasm
in the coal and accompanying strata, which differs from the slip,
chiefly in bearing the marks of a mere fissure or separation ; the
coal seams and other strata being not thrown off their levels, as in
slips ; and the heterogeneous matters with which the chasm ' has
been filled, bearing more plainly the marks of having been brought
there by water.

In slips the coal metals have a vise, which is the vestigia of the
coal, and which leads upwards, or downwards, to the separated
stratum of coal ; but in dykes there is no such vise leading through
to the other side. Sometimes the crack or chasm in the coal, and
in the accompanying strata, resembles the dyke in every respect,
except that the foreign matter is not indurated as in that of the
dyke, but always continues loose, and generally very wet. These
are called GALLS or GASHES.

When the separation is not very considerable, and the strata on
each side the fissure maintain their original position, it is called
A HITCH. In some places, without any apparent cause, the coal

172

turns foul, and is mixed with stone or clay, for a greater or less
extent; this is termed A TROUBLE. In A SHAKE the strata are not
entirely broken and separated by a fissure or chasm, but are only
shaken and cracked, as it were, and thrown into confusion ; the
coal being not altogether lost, but rendered useless ; being
soft, tender, and shattery. The waving SHAKE is that in which,
although there is a waving up and down of the seam, yet it pre-
serves nearly the same stretch and bearing. Some of these do not
continue long before the coal comes in, and is continued again
with its usual regularity ; but others prove very wide and extensive,
even up to several hundred yards. In the twisted SHAKE the strata
are waved and disordered in several directions, dipping in a con-
fused manner as if in various segments of a circle.

Sometimes A BASON is formed in the strata; that is, the hori-
zontal strata, to a greater or less extent, are observed to fall lowest
in the middle, and rise gradually to the outskirts, all round, in the
form of a piece of low hollow ground, in a meadow, which con-
tains a lake of stagnant water in a rainy season. These basons, as
well as the various other positions of the strata, are found upon
various scales, from a quarter of a mile to a mile in diameter*.

Sometimes a waving of the strata into furrows and ridges is ob-
served, the same seam of coal rising many times to the surface.
Sometimes the stratum of coal dips and rises, with the surface of
the ground ; but this is in general not far continued, and seems to
be entirely accidental ; since we shall as often, or indeed much
oftener, find it dipping in opposition to the rising of the surface of
the ground, and passing, in any direction, without appearing to be
at all affected by the figure of the surface.

Coal fields or coal countries are patches of limited but very dif-
ferent dimensions ; the Mid-Lothian coal field is nearly a square of

* Williams's Mineral Kingdom, vol. i. p. 105.

173

about fifteen miles over every way. Frequently, Mr. Williams ob-
serves, the seams of coal rise up to day, and then seem to decline
a little way down from the surface of the earth to a sufficient depth
to be preserved fresh and good, even in full perfection, until the
exigencies of society have occasion for them ; and that, when they
have declined so far, they then become quite flat, and afterwards
rise again upon the opposite side of the coal field, with an opposite
dip and rise, and so form a great trough, resembling a valley;
which is, he remarks, one of the best similitudes of this position of
the seams of coal in a coal field that can be imagined.

Yours, &c.

LETTER XVII.

PARTICULARITIES OBSERVABLE IN DIFFERENT COAL-PITS....
CANNEL COAL.... PYRITES, &C.

HAVING thus endeavoured to furnish you with a compendious
account of the particular circumstances which accompany the dis-
position of coal, I shall, for the sake of supplying a few more points
of comparison, lay before yon- a sketch of some of the more inte-
resting mines of coal; that you may be the better enabled to deter-
mine how far the attempt which I shall make, to account for their
existence, agrees with the phenomena which nature presents to our
observation.

At Bishop-Sutton, near Stowey, in Somersetshire, the first solid
vein is called the stinking vein, from its peculiar impregnation

174

with bitumen ; and at about seven fathom occurs a stony stratum,
called, in that part of the country, cats-heads, from its containing
the substances so called. This vein is two feet in thickness, and
at about five fathom lower down is found, what is called the three-
coal vein, formed of three different sorts of coal ; a stony bed, be-
tween one and two feet in thickness, being between the first and se-
cond vein, but the second vein seems to lie on the third, with hardly
any parting between, being in the whole about three feet deep.
At eight or ten fathom beneath this is the peacock or peaw vein
of coal, the surface of which is marked with eyes, diversified with
colours like the eyes of the peacock's tail. The uppermost surface
of this coal is intermingled with fossil shells, and the vestiges of
fern. At about five or six fathoms beneath this vein, is the smith's
vein, so called from the use to which the coal is chiefly applied. A
little lower than this is what is termed the shelly vein, and about ten
inches lower than this is a vein too indifferent to be worked.

At Whitehaven, at the depth of forty-two fathoms, the roof of
the coal is met with, being a black rock six inches thick, which
has been cleft into regular squares about six inches in diameter,
having an appearance similar to a piece of tesselated pavement.
From Whitehaven to below Thoresby are pits of coal of very con-
siderable depth. At Newcastle upon Tyne, there is a coal-pit,
which is an hundred and thirty fathoms in perpendicular depth,
and which is worked, at that depth, five miles horizontally, quite
across, beneath the Tyne, and under the opposite county of Dur-
ham. In Northumberland towards the more eastern parts, are
pits of coal at thirty fathoms depth. With respect to Cumber-
land^the whole county seems to be a mine of coal and of black
lead.

At Newcastle upon Tyne, Staffordshire, and in some parts of
Scotland, the strata are chiefly composed of stones fit to be applied
to the purposes of building. In Yorkshire, throughout the whole

district of Richmond, in Shropshire, and Leicestershire, and in al-
most the whole of the northern quarter of the island, the coal
approaches in its appearance very nearly to bitumen which has
merely suffered induration.

In Lancashire, near to Pendle Hill, is obtained a species of the
Cannel coal. In Durham the coal is so-near to the surface of the
earth, that the wheels of the carriages lay it open to day, in such
a quantity, as to be sufficient for the use of the neighbourhood,
and to become a valuable branch of income.

At Widrington, near Berwick, bordering upon Scotland, is a coal
pit, the Strata of which, according to Mr. Stracy, are thus dis-
posed. A bed of clay of four yards in depth is first dug through,
when a seam of coal is found about six inches in thickness. The
next two fathom are filled by strata of free- stone, whin-stone, and
potters earth ; then appears a stratum of soft white-stone, and then
coal for about three feet and nine inches in thickness*.

At Auchenclaugh, six miles to the east of Kylsyth, there is a coal
mine eighteen feet in thickness.

At Mall-traeth Marsh, about the midway between the sea and
the farthest inland points of the marsh, they find, whilst digging for
coals, a perfect sea shore, with all the marks of it as pebbles, shells,
&c. under five or six yards of pure sand-j-.

In Scotland, wheYe the coal exists very plentifully, it is in general
of an exceeding good quality, being, like the Cannel coal of Lan-
cashire, almost purely bituminous.

In a quarry about a quarter of a mile above Roslin, and also near
Auchindinny, upon the north side of the river, is a regular, conti-
nuous seam of coal, only about an inch, or an inch and a half thick,
with very strong thick beds of post stone above ; and there are also
several thick seams of coal, both above and below this thin one.

* Philos Transact. 1725. J Rowland's Monae Antiqua, p. 16,

176

At Gilmerton, near Edinburgh, and at Loanhead, about two miles
south-west of Gilmerton, they have a continual change of strata,
on account of their great declivity, which is about the angle of 45°.
The number and variety actually cut through in this field is so im-
mense, that it would fill a large book to enumerate and describe
them all. They are all, says Mr. Williams*, whose work is replete
with the most interesting and useful information, what are commonly
called coal metals, that is, such strata as are generally found to
accompany beds of pit coal ; and there are above sixty strata, or
beds of c*oal, thick and thin, cut through at Gilmerton, in this
noble section : among which about twenty of them have been worked
at Gilmerton, and the neighbouring coal fields. The rest are thin,
though regular strata of coal, generally from about two feet, to three
or four inches thick ; and some of them, though regular strata, not
above one or two inches. In short, the strata cut through in this
great section contain such an amazing number and variety, that they
may be considered as a very complete assemblage, and example, of
all the strata which accompany coal, excepting regularly figured
basaltes, of which there are none at Gilmerton, though they have
cut through several beds of whin, of various colours, which approach
the quality of that stone.

The substances which in general accompany coals demand also
some attention. Among these may be first noticed metallic sub-
stances : thus Valerius Cordus f relates, that, with the bituminous
coals which are dug near Cunharden, there also exists a bituminous
vein of copper and of silver; but iron is the substance most fre-
quently found. Sulphur is also found to abound almost universally
in pits of coal. Neither of these substances are, however, thus
found in a state of purity, but are generally combined together in

* Williams's Mineral Kingdom, vol. i. p. 41.
t Valerii Cordi Observationes, &c. p. 217.

17?

the form of pyrites or sulphurets. The sulphur, however, it must
be remembered, does not enter necessarily into the composition of
the coal, any more than the metal does, except that both are depo-
sited together in the numerous small intersections which every where
divide the substance of the coal ; and frequently they are deposited
in very splendid pyrites, on the surface next to the superior accom-
panying stratum. Thus at Whitehaven, where the coal pits are very
deep, the surface of the slate, which forms the roof to the coal, is
entirely covered with pyrites.

As I shall have repeated occasion to refer to the pyrites, I will
here remark, that pyrites, marcasites, or metallic sulphurets, those
bodies which generally manifest a metallic lustre, and possess at
the same time a crystallized form, are compounds of sulphur and
metal ; the latter of which is sometimes copper, but most commonly
iron. By slow decomposition they derive oxygen from the air,
which, uniting with the sulphur, forms sulphuric acid, which then
acts on the metal, and forms with it a sulphate, or solution of the
metal in sulphuric acid.

Besides these substances, analysis demonstrates that several of
the acids, in combination with some of the alkalies and of the
earths, but chiefly with the latter, are blended with the coal. These
acids are also found in the accompanying strata of coal pits, and
sometimes add to the pecuniary advantages derivable from those
real mines of wealth.

Thus the earth, or stone, accompanying coal, is frequently em-
ployed for the formation of alum, it possessing almost all the princi-
ples of that salt. By long exposure to the air and moisture, or by a
judicious application of heat, and a subsequent use of moisture, the
sulphuret of iron undergoes the following change : the sulphur be-
comes oxygenized; and the acid thus formed, uniting with the
metal, forms a sulphate of iron. A second employment of heat,

VOL. i. A A

178

and of subsequent moisture, produces such a change on the iron,
that it is no longer capable of being held in combination with
the acid, which therefore unites with the clay. An addition of pot-
ash, and of ammonia, that contained in pu trifled urine being gene-
rally employed, being now made, a deposition of earthy and ferru-
ginous matter takes place, and then the remaining liquor being
drawn off into another vat, the crystals of this triple salt are soon
formed.

The whole of that part of the territory of Liege which is dug for
coal, is also worked for the alum earth ; considerable quantities of
alum are said to be found there, formed in crystals on the slate,
and adhering to the clefts of the free-stone.

By a little alteration of the above described process, the sulphate
of iron, or, as it is improperly called, green vitriol, or copperas, is
obtained from the pyritous strata which accompany coal.

The melting of the bituminous matter of coal is very often suf-
ficiently apparent in the burning of coal in our ordinary fires. But
by the action of heat on this substance, in close vessels, or in a
proper apparatus for distillation, its constituent parts are acertained
with a tolerable degree of certainty. The products thus obtained,
are, a water impregnated with ammonia, concrete carbonate of am-
monia, and an oil, which becomes more heavy, and of a darker
colour, in proportion as the operation advances. At the same time,
a considerable quantity of elastic and inflammable gas passes over,
which has been considered as volatile oil in a state of vapour,
but which really is hydrogen gas mixed with nitrogen gas, carbon
in a state of solution, and carbonic acid gas. There remains in the
retort a scorified cindery matter, which is yet capable of burning,
and is exactly the same as the coke, which is frequently made on
a larger scale, for particular purposes, where its mode of burning
is more desirable than that of coals. The ashes of coals yield the

179

sulphates of iron, of magnesia, of lime, and of alumine ; but if
the combustion be carried on with a considerable degree of rapi-
dity, the bases only of these salts are left*.

According to Mons. Morand, eight pounds of Scotch coal pro-
duced thirteen ounces of a saline water, one ounce of a volatile salt,
six ounces of dark-coloured oil, resembling petroleum in colour and
smell, and left six pounds and a half of cinder. He suspects that
the oil of coal obtains its colour, and perhaps its smell, from a
small portion of sulphur which enters into its composition, since
he finds silver is blackened by it in the same manner as by the bal-
sam of sulphur, which is a combination of sulphur with oil.

Yours,, &c.

LETTER XVIII.

BITUMINOUS FERMENTATION. ...COMPARED WITH THE OTHER
SPECIES OF FERMENTATION. ...BITUMENS, THE RESULT OF THIS
PROCESS... .PEAT, A VEGETABLE FOSSIL, THE FIRST PRODUCT aF
THIS FERMENTATION.

.HAVING supplied you with the most interesting particulars, re-
specting the properties of bituminous substances, and the situations
in which they are found, I shall now endeavour, aided by the ob-
servations of those who have preceded me in this path of science,
and by the light yielded by the later discoveries in chemistry, to
ascertain their actual origin, and to propose a conjecture as to

* Syst..des Connois. Chern. vol. viii. p. 243..

180

the nature of that process which has been instituted for their for-
mation.

A careful investigation of the subject has led me to believe, that
the mineralization, or petrifaction as it is generally called, of vege-
table mater, is primarily dependent on that process, by which the
formation of bituminous substances is accomplished. To this pro-
cess I therefore necessarily call your attention.

We have already seen, that vegetable matter, deprived of life,
suffers, on the surface of the earth, a certain decomposition, by
which some of its principles, becoming volatilized, are diffused in
the surrounding atmosphere, whilst others enter, on the spot, into
new combinations, and there form a substance called vegetable
mould, replete with all the principles necessary to yield the proper
pabula to a succeeding race of the same class of beings. But other,
and very different changes to those which take place on the surface,
were necessary to be decreed, for those vegetable substances which
are buried far beneath the surface of the earth.

In some cases, it is highly presumptive to measure the wisdom and
providence of Omniscience, by our narrow judgments ; and it is bor-
dering on profanation to point out, as the wonderful contrivance of
the Deity, those arrangements which may be only the creatures of our
own fancy and imagination. But I trust that, in this conjecture, I do
not err. The path of nature appears here too plain to be mistaken.
The resolution of vegetable matter into mould fit for the future
growth of vegetables is the result of a design, the end of which is
evident. But when vegetable matter is deposited at depths lower
than the roots of vegetables ever reach, a conversion into a sub-
stance of this kind would be useless ; and nature, it must be remem-
bered does nothing in vain. Another process is therefore instituted ;
and instead of a substance being produced, calculated to promote
vegetation, where vegetation never takes place, another substance is
formed, totally different in its nature.

181

The process by which this substance is formed I shall take the
liberty to consider as of the fermentative kind, and shall distinguish
it by the name of BITUMINOUS FERMENTATION; defining it — A
fermentation peculiar to vegetable matter placed in such situations, as not
only exclude the external air, and secure the presence of moisture, but
prevent the escape of the more volatile principles ; and which terminates
in the formation of those substances termed bitumens.

Having here distinguished this process, for the first time, as a
species of fermentation, its right to such a distinction ought to be
ascertained as soon as possible ; but as the circumstances on which
its claim depends are to be found in the history of the phenomena
it produces, and of the results of its operation, we will first hasten
to their consideration.

In a process carried on in the recesses of the earth, or, at least,
in situations from which our observations are excluded, it is not to
be expected, that a complete history of all the phenomena which
occur during the whole of the operation can be possibly made out.
To furnish a satisfactory account, we must have recourse to infe-
rence and analogy ; thus aided, we may, I trust, with only the pro-
duct of the operation before us, be enabled to form well-founded
conjectures on the phenomena which have actually taken place.

Almost all vegetable matters manifest a strong disposition to de-
composition, when the separation of their integrant molecules is
aided by the interposition of the particles of water ; and particularly
if, with this, is combined the powerful energy of caloric. If this
latter agent be employed, only in a low degree, an intestine mo-
tion among the integrant molecules takes place, the equilibrium
by which that particular mode of composition was preserved is
broken, a separation of the constituent principles takes place, they
become influenced by new attractions, and then enter into new
combinations and modes of existence. By this process, the fer-
mentative process, a resolution of the original compound is effected,

182

and new substances are formed, differing much in their physical, as
\vell as their chemical properties, from the substance from which
they have proceeded. One particular point in which they almost
always differ may be here very properly noticed. The combina-
tions resulting from these spontaneous changes, occasioned by
the intestine motions of the constituent principles, regularly pro-
duce substances less' compounded than those which these prin-
ciples previously formed. Before the final change, however, is
completed, certain regular periods in the process must be passed
through ; and the substance exposed to the operation must necess^
arily exist in several intermediate states. In passing through these
different states it acquires new and peculiar characters ; and may
be arrested in any one of these stages of transformation, and so
fixed, that it shall pass on to no further change.

Between the phenomena of fermentation in general, and those
which accompany that which I term the bituminous fermentation,
I trust you will perceive a total agreement, when the latter are
more particularly examined. But that this may more clearly ap-
pear, I will proceed to take a more particular view of the effects of
this process, with those proceeding from the other species of vege-
table fermentation.

Vegetable matter, then, I consider as subject to five different
species of fermentation, each of which appears to be, in a great
measure, dependent on the degree to which the access of air and
water is admitted.

The saccharine fermentation takes place in those parts of vege-
tables in which the saccharine principle seems to be present, and
merely to require evolution, as in the roots of the parsnip, beet, &c.
the monocotyledon seeds, &c. This principle acquires a saccharine
form merely by the attraction of oxygen from the atmosphere,
d uring the germination of these seeds ; in which state it is pre-
erve d by the common operation of malting. From other parts of

183

vegetables it is obtained by certain chemical processes. The sac-
charine fermentation appears to be the agent by which fruits ac-
quire an encrease of their sweetness, after being plucked from the
parent stock, when no action of vegetable life can go on. By an
acceleration of this process, by the aid of caloric, in the operation
of baking, this effect is still more manifestly produced.

If to vegetabje substances possessing this principle, an addition
of water be made, and a slight increase of caloric be made, an in-
testine motion soon takes place, called, from its product, the vinous
fermentation. During this process, the object of which appears to
be, the diminishing the dose of carbon, which is united with the
oxygen and hydrogen in the sugar, we find carbonic acid gas is
rapidly separated, a feculent sediment is deposited, and a new
substance, called yeast or must, is formed, which rises to the surface,
and which, if added to any vegetable infusion containing the sac-
charine principle, will immediately excite that peculiar intestine
motion on which this species of fermentation depends.

When this separation has taken place, but whilst the fermenta-
tive motion is still discoverable, if the fluid be carefully preserved
from the access of the air, it passes on, through an almost, and, in
the latter stages of it, an entirely, imperceptible fermentation, during
which it obtains its highest degree of strength, becoming a clear
and bright spiritous intoxicating liquor.

But if, instead of this seclusion, the process be allowed to go on
in contact with the atmospheric air, instead of a spiritous liquor,
a peculiar vegetable acid, or vinegar, is the result ; which will also
require, for its preservation, a seclusion from the atmospheric air,
since otherwise it will suffer a further decomposition, its volatile
principles escaping, and its earth and carbon only remaining.

Thus also will almost any mass of dead vegetable matter, exposed
to the air of the atmosphere, soon pass on to a putrid fermentation,

184

by which its constituent parts will be made to enter into new com-
binations. The hydrogen, uniting with the oxygen, is either vola-
tilized in water, or, combining also with a portion of carbon, is
separated as carburetted hydrogen gas ; the remaining portion of
hydrogen giving colour and odour to the mass. Of the carbon,
that which is not engaged with the hydrogen, either unites with the
oxygen, and forms carbonic acid, or constitutes a part of the
magma, of which, however, by far the most considerable part
is the earthy matter, which entered into the composition of the
vegetable.

But if, instead of being thus exposed to the influence of the air,
a mass of dead vegetable matter be accumulated in such situations
as allow of the admission of water ; but in which, by the compact-
ness of the superincumbent stratum of earth, not only the external
air is shut out, but the disengaged gaseous matters are prevented
from escaping, the bituminous fermentation I suppose to take place;
and bituminous matters are formed in various degrees of maturity
and purity according to the stage at which the process may have
arrived, or to the extraneous matters which may have been ad-
mitted.— But I do not, however, wish you to forget, that, of the pro-
cess I have here described ; I am not able, for the reasons already
given, to adduce direct proof; the proofs of its having taken place
must be obtained by inference, and from analogy.

This I shall now attempt; and shall hope that, by comparing this
with the other species of fermentation, and by examining the results
of this process, we shall be able to form more reasonable conjectures
as to the nature of the new combinations into which the principles
have entered.

The substance, then, which I conceive to be entirely dependent
on, and actually the product of this process, is bitumen ; a sub-
stance- which manifests, upon examination, all those properties which

185

might, d priori, be expected to be found in a body constituted under
the particular circumstances which I have presumed to have directed
its formation.

In the first stage of the vinous fermentation, we perceive that a
considerable portion of the more volatile parts of the mixture is
dissipated ; and that it is only by the careful preservation of the
remainder that the accomplishment of this process is effected. In
the acetous fermentation, this escape of the volatile parts is conti-
nued through the whole of the process, and occasions the great
difference which exists between the two products. In the first of
these species of fermentation, carbon is, we have remarked, dissi-
pated in very large quantities, by which its dose in the mixture
must be considerably diminished ; whilst, should hydrogen even
be supposed to escape in a similar proportion, still, from the decom-
position of the water, sufficient of this principle, which I will call
the principle of inflammability, will be yielded, to assist in forming
the spirituous and very inflammable product which we find to be
the result of this process. In the latter of these species of fermen-
tations, in which the dissipation of the volatile matters are carried
to the utmost extent which the degree of temperature will admit,
the mixture appears to be deprived of almost the whole of its hy-
drogen ; except, perhaps, just so much as is left in combination
with the colouring principle, and in the water, whilst the oxygen is
freely attracted, by the carbon, from the atmosphere; and from its
abundance, and from some peculiar modification in the combi-
nation, the product, vinegar , results, possessing a high degree of
acidity, but not the least degree of inflammability.

We will now examine the changes which may be expected to
result from the decomposition of vegetable matters placed in sub-
terranean situations, and considering these, with the properties
which are possessed by the supposed product of the bituminous

VOL. I. BB

186

fermentation, shall be enabled, especially by recollecting what has
been just said of the other species of fermentation, to determine
whether it is right to admit of the existence of such a species of
fermentation or not.

Secured on every side by the surrounding earth, the mass of
vegetable matter is preserved, as it were, in a well-closed vessel ;
hardly any escape being permitted to its more volatile particles ;
nor any admission of extraneous matters allowed, except of such
as are introduced with the water, which insinuates itself by soaking
through the interstices of the earthy particles, composing the several
strata which inclose it. This mass of vegetable matter, now deprived
of the energy of vegetable life, must undergo some change ; but,
from the closeness of its preservation, it cannot admit that escape of
the gaseous matters on which the commencement of the vinous, ace-
tous, or putrid fermentation depends : another process is therefore
instituted. The hydrogen, carbon, and oxygen are disengaged from
their former attachments, but, being prevented from flying off in a
gaseous state, are obliged again to unite, and to enter into new com-
binations. Under these particular circumstances, a substance may
be expected to be formed containing a considerable portion of these
principles so abundant in vegetable matter. In this respect, there
undoubtedly may be discovered a remarkable agreement between
the supposed product of this fermentation, and the assumed process
by which its formation is attempted to be explained ; since, in all
bituminous substances, the abundant existence of these three prin-
ciples has been sufficiently proved by analysis.

In this, as in every other species of fermentation, a considerable
difference may exist, as to the degree of perfection to which the
process may proceed, and, of course, as to the degree of perfection
which the product may possess. Thus I expect to shew, that, ac-
cording to length of time, exclusion from the air, and the existence

187

of other favourable circumstances, will these bituminous substances
be found, in their several approaches to that state to which the laws
of nature seem to have particularly destined them.

Peat, that combustible and inflammable substance, generally
found in considerable masses at a little depth beneath the surface
of the earth, possessing chemical properties essentially different
from every other substance which has not derived its existence from
the same origin, appears to be the first product of this kind of fer-
mentation, and to have been formed in situations not favourable to
the rapid completion of this process. The celerity with which this
process is accomplished must depend on the closeness with which
the gaseous principles are secured ; but it should be considered,
that such peat-bogs, as are comparatively but of modern formation,
are covered by a coat of vegetable mould, in an humid state, of no
considerable degree of thickness, and therefore the escape of the
more volatile principles, and the admission of atmospheric air, is
only partially prevented ; the process must therefore be carried on
with much less effect than in those cases which will be hereafter
mentioned, where vast masses of vegetable matters have been sud-
denly buried under a considerable thickness of earthy deposition.

The abundance of hydrogen, carbon, and oxygen, in peat, is
sufficiently demonstrated by its analysis. By the early analysis of
Schoockius, we learn that it yields an oil much resembling the oil of
amber, with an acid liquor. Mons. Fourcroy relates, that, on expos-
ing peat to the action of heat in a distillatory apparatus, a yellow or
reddish foetid water is obtained, an oil of a most disagreeable odour,
with carbonate of ammonia, and carbonated hydrogen gas, also
smelling most disagreeably ; a coal being left which is frequently
pyrophoric, and which yields, after incineration, muriate and sul-
phate of soda and of pot-ash, mixed with the phosphate and sul-'
phate of lime, and with the oxides of iron and of manganese *.

* Syst. des Connois. Chem. torn. viii. p. 233.

188

The prevalence of hydrogen in this substance is fully displayed
by the foregoing analysis, since not only enough exists for the for-
mation of this peculiar oil, but a considerable quantity of this
principle is also disengaged in a gaseous torm : the agreement,
therefore, between this substance, and what might, d priori, have
been supposed would be the product of vegetable matters placed
under these particular circumstances, appears to be evident. The
original mode of existence which belonged to this substance is suf-
ficiently marked, by the great quantity of vegetable substances
which are found in it, which have not suffered such an alteration
as to hinder the immediately tracing of them to their true origin.
That this substance has been subjected to the influence of the two
circumstances which seem essential to this peculiar fermentation,
the presence of moisture and subterranean situation, must appear
so plain from the descriptions you have already had laid before you
of the state in which peat-mosses are found, that, on this point, not
a word need be added. Peat, therefore, I presume, we may regard
as a vegetable secondary fossil ; having been formed from vege-
table matter, changed in its nature and properties by a certain fer-
mentation, which has been carried on in the mineral regions.

Yours, &c.

LETTER XIX.

FOSSIL TREES, IMBEDDED IN PEAT, HAVE UNDERGONE THE BITU-
MINOUS FERMENTATION. ...THE CHANGES WHICH MOW-BURNT
HAY UNDERGOES, SOMEWHAT SIMILAR TO THAT PRODUCED BY
THE BITUMINOUS FERMENTATION.

1 HE fossil trees which are so frequently found imbedded in peat,
may also be considered as vegetable fossils ; and as they appear to
have undergone exactly the same kind, and the same degree of
mineralization with peat, their consideration along with that sub-
stance seems most eligible*

These trees, as appears by the accounts already given, are almost
always found to have preserved their original form and structure so
exactly, as frequently to render it easy to discover what species of
trees they are, even in this their mineralized state. When first found,
these trees are generally of a dark brown colour, manifesting, as
has been already mentioned, the exact form of the original tree ;
but so soft, as to be capable of being deeply cut into by the stroke
of a spade ; and also of so spungy a texture, as to allow a very
considerable quantity of water to be squeezed from them, even by
a moderate degree of pressure. So tenacious are they of the water
they have thus imbibed, as still to retain a- very large portion of it,
even where great pains have been taken to procure its expulsion.

But when, after long exposure to the air, this water has been
evaporated, the substance of these fossil trees assumes different de-
grees of solidity, dependent on the state in which the wood existed
at the time of its exposure to the bituminous fermentation, and cm

190

the extent to which this operation has proceeded. Should the tex-
ture of the wood have been loosened by previous decay, it will, in
its bituminous state, when dry, be found to be in a loose shattery
state; the fibres being hardly discoverable, owing to their having
concreted into irregular fasciculi. The appearance which such
pieces exhibit may be conceived from the specimen delineated in
Plate 1. Fig 1.

But, on the contrary, if the wood had endured little or no pre-
vious decay ; nor has suffered any loss of substance, from the agita-
tion of the water in which it has laid, and has undergone the same
degree of bituminization which peat in general has suffered, it will,
when dried, not only possess its pristine form, but almost its ori-
ginal degree of hardness. Slips of this bituminized wood will
flame, when lighted, like matches made from the fir or pine tree ;
which circumstance has occasioned some confusion, some having
asserted that the trees from which these slips have been taken must,
of necessity, have been of the resiniferous kind, from their possess-
ing so great a degree of inflammability after ages of immersion
in water. This phenomenon, however, is more easily accounted
for, by considering that this substance no longer possesses any of
the original compound constituents (materiauximmediats)9of which
turpentine is one, but that the inflammability depends entirely, on
the wood being now converted into a bituminous matter; which
circumstance is evinced by the particular odour, and other peculiar
circumstances, which accompany the combustion of this substance.

Bituminous wood, sometimes possessing a considerable degree of
closeness of texture, has been very advantageously employed for
many of the purposes to which ordinary timber is generally appro-
priated. From its adoption for such purposes an observation has
been made, which deserves, in this place, particular notice. The
experience of the workmen has led them to observe, that this spe-
cies of fossil wood resists the action of water much longer than

191

other wood ; they therefore choose to employ it in those situations
which are most exposed to injury from that element. Here we
plainly perceive an instance of the powerfully pervading influence
of this species of fermentation — trees so little altered in their struc-
ture as to bear all the ordinary operations of hewing, &c. in the
same manner as common timber, are found to be so far bitumi-
nized, to their very centre, as to have become, when dried, in a
considerable degree impenetrable to water; a property possessed
by all bituminous matter, after having been once dried, in propor-
tion to the degree of perfection to which their bituminization has
proceeded.

That the leaves, and other soft parts of plants, should suffer con-
siderable change by this, or by any other species of fermentation
to which they are subjected, is by no means difficult to understand ;
but that large solid trunks of trees should thus be penetrated, by
this peculiar influence, to their very centre, and that too in those
kinds of woods the substance of which is naturally very dense, can-
not but excite interest and surprise. To account for this astonish-
ing effect, it is necessary to consider the powerful agency of water ;
which, either existing in a separate state, or as one of the consti-
tuent parts of the substances exposed to this species of change,
appears to be as indispensably necessary in this, as in all other fer-
mentations. It is well known that; by the long continued immer-
sion in water of a piece of timber, the particles of water may be
made to insinuate themselves through every part of it; and when
the water is impregnated with the leaven of this fermentation, this,
will of course be conveyed to every part, and thus may we account
for so wonderful a change being effected through the whole sub-
stance. Hereby we discover that this effect, so astonishing at first
view, is accomplished by this two-fold action of the water ; first,
by separating, by its interposition, the integrant molecules of the
wood ; in producing which effect it is perhaps aided by the com-

192

bined action of a portion of caloric ; and, secondly, by conveying
to every point of the vegetable substance the leaven of the bitumi-
nous fermentation ; by the active energies of which fermentation
the whole mass of solid wood is made to undergo an actual conver-
sion, and to pass from the state of wood to that of bitumen.

This particular species of fermentation may be illustrated, by
considering the phenomena which result from vegetable matter be-
ing placed in such circumstances, as we have assumed necessary to
the production of this fermentation, excepting only that of not
being in a subterranean situation. Should we find that vegetable
matter thus disposed undergoes a somewhat similar fermentation,
producing a change approximating to that which takes place in
what I have termed the bituminous fermentation, we shall have
another presumptive evidence of the propriety of distinguishing
the process by which peat is formed, as a species of fermentation.

The situation in which we find vegetable matter thus disposed, and
in which the effects are immediately under our own examination, is
that in which the various species of grass, Sec. are so closely stowed
together, and in such quantity, that the weight and thickness of the
superior layers must totally prevent all access of the external air,
and any escape of the separated gases. You must have already
perceived, that I here refer to the process employed in hay-making;
and you well know, that when this operation is conducted accord-
ing to the wishes of the farmer, that the saccharine fermentation,
or a fermentation nearly resembling it, only takes place ; and the
grass is changed into hay, which possesses a peculiar fragrance and
sweetness. But should the grass, at the time it is heaped together,
unfortunately retain too much water, very different effects will fol-
low: heat will be rapidly evolved, and a dense vapour will be seen
to exhale from the mass. If the process be stopped in this stage,
the mass of vegetable matter will be found to have acquired a very
dark brown colour, and a glazed surface, and to emit a strong

193

peculiar odour, resembling that of empyreuma, or of bitumen. In
this state it is generally known by the term mow-burnt hay. But if
the process be allowed to go on, the heat soon considerably aug-
ments, the vapour assumes the form of smoke, and, at length,
actual flames break forth, and the whole mass is presently reduced
to ashes.

The remarkable evolution of heat, in the fermentation I have just
spoken of, demands an inquiry whether any thing similar ever takes
place in the process of bituminization ; since, if that be not the
case, the parallel would so far fail. But, as the process of bitumi-
nization is carried on out of the reach of our examination, it is
impossible, as has been already observed, to speak accurately re-
vspecting the phenomena which arise during its performance. The fol-
lowing account, however, contained in a letter from Peter Collinson,
Esq. to Sir Hans Sloane, which I met with among the unprinted
papers of the Royal Society, preserved in the British Museum, shows
that tliis phenomenon may arise during this process. You will also
perceive that the learned writer proposed to account for its occur-
rence in a similar manner with that which I have here adopted.

" Our newspapers, printed here, mention the burning of Brooks,
in the Vale of Good Cheap; but the case is, that some pieces of
marshy ground, called brooks, from their watery situation, have
flamed for some time; and these they have called burning brooks;
the parish next adjoining is also called Brooks. The soil is like
those parts of Cambridgeshire, where the turf is cut, and very often
under water ; but this dry season has brought it from very wet to
that degree of moisture which often causes hay to ferment and
take fire. Accordingly, this fire begins about four feet underground,
just above the water (as appears by digging), and so burns up to
the surface, where it flames out, especially if stirred with any thing ;
and, according to the quantity of .roots and fuel it meets with, it
leaves strata of black coal, or red ashes. The fire has now burnt.

VOL. i. c c

194

for several weeks, and is expected to continue till the rain or springs
extinguish it. The same land burnt, in the same manner, about
forty years ago. Perhaps this hypothesis, of its kindling by fer-
mentation, may be confirmed by the frequent firing of hay-stacks
this year, of which we have had many more instances than in several
years before/'

Upon the authority of Schoockius, we learn that this species of
combustion is no rare occurrence in the peat-pits of Germany.
More or less frequently, he says, it happens ; but chiefly when the
heat has been more violent, and the rains have fallen less plentifully,
that either by accident, or by some one's malice, not only the dry
peat, but even the marshy earth itself, become drier than usual,
is set on fire ; when the flame spreads far and wide, occasioning a
calamity, not less dreadful to those labourers who dwell at the pits,
whose little hovels it lays waste and reduces to ashes, than to those
who derive their livelihood from these pits. For this reason, proper
watchmen are appointed to go round, not merely to keep it toge-
ther in heaps, but to be ready to extinguish, in time, the fire which
might break out. This they do not so much by water, which is not
always found in sufficient quantity, as by smothering it, by turning
over it with shovels the adjoining earth. If this be not done, the
flames continually acquiring more fuel, the fire ravages, not for a
few days, but for weeks and even months, as dreadful experience
has shown, so that the extended plain may be regarded as a lamen-
table and distressful kind of volcano.

Thus far, I may surely venture to remark, that analogy confirms
the opinion, that peat is the product of peculiar fermentation.

Yours, &c.

LETTER XX.

EXAMINATION OF OPINIONS, RESPECTING THE ORIGIN OF PEAT
....ABORIGINAL FORM AT1ON.... A MARINE DEPOSIT.. ..MINERAL
ORIGIN. ...FLOATING ISLANDS.. ..A RECENT VEGETABLE SUB-
STANCE.

ALTHOUGH I encourage the hope, that the circumstances adduced
are such as will be likely to be successful, in establishing the opi-
nions I have offered, respecting the origin and nature of this sub-
stance ; yet something more remains to be done. The opinions
already advanced, on this subject, have a claim upon our attention ;
and although the greater part of them may not require a formal
refutation, others will require to be examined, that it may be de-
termined whether they offer a satisfactory explanation of the pro-
perties which are possessed by this substance. It is likewise incum-
bent to determine whether those particular circumstances, which
have been supposed most powerfully to support the hypotheses
which have been already advanced, militate against, or favour,
that which is here attempted to be established.

The first opinion 1 shall notice is that which supposes peat to
have existed, in its present form and state, from the creation of the
world. In opposition to this opinion it must be sufficient to ob-
serve, that peat is composed of substances which bear the indu-
bitable marks of having existed in another state ; also that there
is an abundance of instances of its formation going on, even at
the present day.

The hypothesis, which supposes it to have been formed by a bitu-
minous deposit from the waters of the sea, must be rejected, from
its being impossible thus to account for the prodigious quantity

196

t)f vegetable matters, of which it is so evidently composed. The
distinctness of vegetable form and structure, which is thus displayed,
and which incontestably proves their previous existence in this mass,
serves also to refute the opinion, promulgated by Pliny, and adopted
by Schoockius and others, of this substance being entirely of mineral
origin ; and of its being originally formed in its present situations.
r < Those who have endeavoured to account for the formation of
peat, by the sinking of large floating islands, which have afterwards
become covered by the accumulation of strata of other earth, ap-
pear, certainly, to have mistaken the cause for the effect. This will
I think appear sufficiently plain by examining the following very
curious account of the appearance of these islands, as well as of
the phenomena which precede and accompany their formation, as
given by a gentleman who appears to have almost witnessed the
separation of these floating islands iti the lake of Derwentwater.

The lake of Derwentwater is celebrated for the astonishing phe-
nomena its waters exhibit. At uncertain times the waters of this
lake experience very considerable agitations, the waves running to
a great height, and forming large white breakers, on which the
boats are tossed as though in a severe storm ; whilst none of the
usual causes of such commotions of water are discoverable. The
waves differ from those produced by ordinary causes ; not rolling
along from one end of the lake to the other; but rising, in moun-
tainous heaps, from ten inches to two feet in height ; as though
raised by some powerful elevating force, applied underneath : and,
in agreement with the idea thus suggested, the people of the neigh-
bourhood term this phenomenon a bottom wind. Sometimes the
whole surface of the lake is thus agitated, at other times it is only
partially affected ; and frequently it will strike a boat with so much
force, that it will appear as though it had struck against a rock : a
very considerable roaring noise often accompanying these surprising
appearances.

197

A phenomenon, not less interesting and astonishing, is the ap*
pearance of floating islands on this lake. These rise, at uncertain
periods, from the bottom of the lake : sometimes one, and some-
times two, have arisen in a year; and, at other times, several years
may elapse without their appearance. Their time of remaining at the
surface is also very uncertain ; some sinking again, within twenty-
four hours ; whilst others remain for six weeks, two months, or even
longer, before they return to the bottom of the lake ; which they
in general do without having suffered any change in their form :
but sometimes they burst, and are so widely rent, that boats can
pass between the separated parts. One rose in 1798, which was
one hundred and eighty yards long, and fifty yards wide. They
sometimes show above a foot high of land, out of the water; and
some have been measured which have been seven yards in thickness.
The upper part of these masses, for about two feet in depth, is
common mud ; beneath this it becomes less compact, and the re-
maining part is found to be formed of decayed leaves and roots of
plants and trees.

A pole being passed three or four feet into them, a considerable
quantity of air rushes out on its being withdrawn : this air smells
like gunpowder ; and it is said that, if collected in a bottle, it will
take fire if exposed to the flame of a candle*.

The most prominent circumstances in the foregoing relation are,
the matter of which these islands are chiefly composed; the gaseous
matter which is so plentifully liberated, from an opening made into
its substance by means of a pole ; and the extraordinary impulse,
and agitation by which the water of the lake is affected. These
several circumstances we will therefore subject to a careful and
impartial examination.

All, except about two feet of the upper part, of these islands,
appears to have been formed of the decayed leaves and roots of

* Phil. Mag. No. XLII.

198

plants and trees ; and such we well know is v|he appearance which
is yielded by peat in certain periods of its formation. This mass,
then, of decayed leaves and roots of plants, and of trees, as described
by the ingenious observer, was undoubtedly a mass of long buried
vegetable matter, part of a stratum of peat, passing through the bitu-
minous fermentation ; and which had become covered with water.
The opportunity of its separation had doubtless been given, by the
superincumbent strata having been so reduced by the excavation
which formed the lake, as not to leave a sufficient thickness and
strength to resist the expansive powers of the gaseous matters ; and
these, by their extrication, had separated the mass, which, from
its lightness, floated on the water.

That this bituminous fermentation was actually going on may be
reasonably inferred, from the nature of the gas which was expelled ;
its peculiar odour, and its imputed inflammability, strongly denot-
ing the presence of hydrogen ; the separation, and the subsequent
fixation pf which have been assumed as important steps in this pro-
cess. Another circumstance yields very strong collateral evidence,
that this operation had proceeded to a certain length. The specific
gravity of all bituminous substances is, generally, less than that of
the vegetable matter from which they have been formed ; this is
most certainly the case, when wood has suffered this species of
conversion. As this process has therefore gone on, the substance
has become specifically lighter, and cavities have been formed by,
and distended with, the detached hydrogen, which must have also
increased the levity of the mass, and enabled it, even with the
superincumbent earth, to make its ascent through the water.

It may also be remarked, that the eruption of these gaseous mat-
ters in considerable quantities is sufficient to account for the agita-
tion of the waters, and for the other phenomena which are described
as appearing to have been produced by some powerful, elevating
force, applied underneath.

199

Dr. Plott, in his mention of the floating islands of Kinson Pool,
in Staffordshire, points out plainly the nature of the substances
with which these floating islands are originally composed*. He says,
'* of a kind of stringy bituminous earth (roots and oily substances
being very buoyant) the floating islands, so much talked of and
admired in many parts of the world, are most certainly constituted,
whereof there are two about twenty feet broad, but about thirty or
perhaps forty feet long, in Kinson Pool, which An. 1680, began, in
March, to move from under the hill, on the N.W. side of the pool,
and came together, like the simplegades, first to the S.W. corner,
where after they had continued about three weeks, they began to
move again, and were come in May (when I was there) to the S.E.
corner, lying just in the passage of the water, out of the pool, to-
wards the mill. I was also told of such in Aqualat Meer."

The only opinion we have now to examine is one which from
the abilities, and opportunities of observation, of its ingenious au-
thor, must claim our serious attention. The hypothesis to which
I allude is that of Dr. Anderson, than whom few have possessed
greater opportunities of making observations on this substance,
or have endeavoured with more zeal to employ those observations
for the public good. He candidly remarks, that, after long and
attentive observation, he has only been able to fix upon one fact
respecting this subject, which seems to be incontestably proved —
that moss has been produced by a gradual accretion, and has not
been created at the beginning of the world, in the state we now
find it.

Dissatisfied with previous hypotheses respecting the formation of
peat-moss, particularly with that which supposes it to be entirely
formed of wood ; that which supposes that there may be some kind
of extracts from the wood, somewhat of the nature of tan, which,

* The Natural History of Staffordshire, p. 114.

200

by the medium of water, preserves the fog or moss which grows
among the decayed trees, and converts it into peat-moss; as well as
that which attributes its origin to a certain state of preservation of
the sphagnum palustre and some kinds of confervce, the Doctor offers
an hypothesis of his own.

Can it be, he asks, that peat-moss, as we find it in its natural
state, is, of itself, a vegetable production, not a conjeries of dead
plants preserved by some mystical influence, as has been generally
supposed, but actually alive, and in the highest degree of perfection
of which it ever is susceptible ?

After considering this question with the greatest attention I am
capable of bestowing upon it, I feel myself strongly inclined, the
Doctor says, to answer in the affirmative, notwithstanding the re-
luctance I felt at first to give into that opinion, on account of the
singular appearance of this substance. In its analysis, recent qua-
lities, decomposition, and final decay, every circumstance tends to
point it out as a recent vegetable substance possessing certain pro-
perties of fresh vegetables, particularly inflammability in a high
degree of perfection. Its appearance is indeed very unlike to those
vegetable substances we have been used to observe, and more
nearly resembles a mass of putrid vegetable matters than a real
living substance. But were, the Doctor observes, appearances alone
to be trusted in matters of this kind, many vegetables would have
been degraded from that class. The sponge, growing in large irre-
gular masses, more resembles an aquatic excrescence, than a regular
organized vegetable production. The truffle, which buries itself in.
the earth, and never appears at all above ground, would seem to
rank rather in the fossil than in the vegetable kingdom. Several
kinds of fungi, which spring out from wounded trees in irregular
lumps, have infinitely more the appearance of a gummy concre-
tion, hardened by the air, than of an organized vegetable. The
lichen, which spreads itself upon the surface of humble plants, bears

201

such an exact resemblance to fragments of decaying leather, scat*
tered on the ground, that it requires a near examination to satisfy
an unskilful observer, that it is not so. How different are all these
from the sturdy tree whose roots strongly grasp the earth and draw
from thence abundant nourishment to support the stately pile which
rears its lofty top in wild luxuriance to heaven ! Were general re-
semblance alone to be relied upon, these very dissimilar substances
could never be included in the same class. But the forms which
heaven has pleased to impress upon organized matter are so in-
finitely diversified, as to compel us to have recourse to other more
accurate means, than general appearances, for ascertaining the
nature of these substances which attract our attention. But, from
the foregoing observations, it appears, the very criterion by which
we can examine this substance, its form and appearance alone
excepted, proclaims it to be a recent vegetable substance, and nothing
else. Why then, the Doctor concludes, should we be startled at
appearances in this instance, which we have been obliged to disre-
gard in so many other cases of a similar kind ?

Having now iaid before you the Doctor's hypothesis, in his own
words, I will in a summary way state to you the evidence which he
adduces in support of it. The solid compact nature of the moss
plant, as the Doctor calls it, he thinks ought not to be allowed to
make against his theory, since the diversities of plants, as to their
modes of growth, are so great, as to give us sufficient reason not to
think of limiting the laws of nature in this respect. It is certain,
that all mosses have been augmented by an increase of real quick
moss, since their first formation. This augmentation, the Doctor
thinks, can have happened in no other way than by its increase, in
the manner of growing vegetables, from the time of its first germi-
nation till the present hour. But what is the nature of the seed or
sperm of this supposed moss plant ; how it was first planted ; in what
manner its increment has been effected ; or how it should have been

VOL. i. DD

202

determined to grow in one place and not in another ; the Doctor
acknowledges he cannot pretend to say. But from every considera-
tion he thinks there is much reason to believe, that moss is, in effect,
a vegetable matter sui generis, which is produced in proper circum-
stances, though we are as yet ignorant of what these circumstances
are ; that it continues to increase to an immense magnitude,
and to live to an indefinite age ; and that in its progress it enve-
lopes trees, and every other matter that comes in its way, which it
either consumes or preserves, according as the peculiar nature of
each are liable to be effected by its juices : preserving its own pro-
perties undiminished, as far as we yet know, until some part of it
be cut off from the general mass; after which, as has been said, it
evidently ceases to live, and goes through the same process of de-
composition and decay as every other vegetable substance.

A similar opinion with this of Dr. Anderson's was entertained by
Dr. Plott, who says, that the stringy roots that, together with the
bitumen, make up the peats, do never flourish above the surface ;
and if so, he says, I am confirmed in an opinion, that there are
many subterraneous plants not noted, of which I intend a diligent
inquiry *.

Without trespassing upon your time with a regular discussion of
the Doctor's hypotheosis, I will only dwell, for a little time, on two
or three circumstances which I think strongly opposeit.

Did peat owe its formation to the supposed moss plant* we should
not expect to find it, as it often is found, almost entirely composed
of other species of vegetable matter. Indeed that which is here
supposed to have originated, in one particular mode of vegetation,
appears to depend on a certain change which affects vegetable
matter in general; but perhaps some parts of the vegetable crea-
tion more than others* Thus the conferva and the, mosses, and par-

* The Natural History of Oxfordshire, by Dr. Plott, p. 16,

203

ticularly the sphagnum palustre, appear to be vegetables which are
peculiarly calculated to suffer a conversion into this kind of
substance.

The promptitude with which the species of plants, which I have
just enumerated, appear to submit to this change, and their dispo-
sition extensively to spread themselves, through every interstice of
such peat-bogs as they have possessed themselves of, may perhaps
account, in a great measure, for that augmentation of peat-mosses,
which the Doctor evidently considers as highly confirmatory of his
opinion. The Doctor says, ''It is certain that all mosses have
been augmented by an increase of real quick moss smce their first
formation. This augmentation/' the Doctor says, " can have
happened in no other way than by its increase in the manner of
growing vegetables, from the time of its first germination till the
present hour."

To prove that this augmentation is not of growing peat, but of
vegetable matters under the influence of the common laws of vege-
tation ; and, at the same time, to point out more clearly what seems
to me to be the actual circumstance, which appeared to corroborate
the Doctor's opinion, I must lay before you the account of this
process, as delivered by an eye-witness.

Dr. King, in a paper presented to the Dublin Society, says,
" that Ireland doth abound in moss more than I believe any
kingdom, insomuch that it is very troublesome, being apt to spoil
fruit-trees and quicksets. — This moss is of divers kinds : that which
grows in bogs is remarkable ; your light spongy turf is nothing but
a congeries of the threads of this moss, before it is sufficiently rotteo
(and then the turf looks white, and is light). I have seen it in sucr
quantities, and so tough, that the turf spades would not cut it :
in the north of Ireland they, by way of joke, call it old wife's tow,
and curse her that buried it, when it hinders them in cutting the

204

turf : it is not much unlike flax : the turf holes in time grow up
with it again, and all the little gutters in bogs are generally filled
with it."

Another circumstance, on which Dr. Anderson dwells, demands
a little consideration. This moss plant, he conceives, may live to an
indefinite age, and increase to an immense magnitude, enveloping,
in its progress, trees and every other matter which comes in its way ;
which it either consumes or preserves, according as the peculiar
nature of each are liable to be affected by its juices. But the
effects here mentioned are very different from what the appearances
in peat manifest. The trees- and other vegetable matter, which, for
argument sake, we will for a moment consider as being thus enve-
loped, are neither consumed, nor preserved, in the sense in which
these words are here employed, but actually changed into a sub-
stance of a different nature from, and exactly agreeing with that
of the surrounding matter. That any living vegetable should possess
chemical and physical properties essentially different from all vege-
table matter, which is the case with peat, and should possess the
power of so assimilating to its nature all vegetables it invested, as
to' form with them a homogeneous mass, cannot therefore, I con-
clude, be admitted.

Bovey coal, that species of bituminous wood, so particularly men-
tioned in a former letter, as abounding so plentifully at Bovey in
Devonshire,, and at Munden in Germany, I must here observe to
you, appears to be wood more highly bituminized than fossil wood
is in general; and may be considered as next in progression to com-
plete bituminization. The fibrous structure, so evident in most of
its specimens, plainly evinces its ligneous origin ; and the undulated
and confused direction of its fibres (seen in Plate I. Fig. 2.) shews
that, by some process, they have been so much softened, as to have
admitted a distortion from their natural direction ; whilst its;

205

chemical properties sufficiently testify its bituminous nature. It
appears to have been formed from vast deposits of wood, which
have been so circumstanced, as to have undergone the bituminous
fermentation to a certain degree ; but have not suffered a change
sufficient to reduce it to a fluid bitumen. That a portion of it has
undergone, even this change, may justly be inferred, from the actual
presence of bitumen in different parts of the mass ; as well as from
the bituminous impregnation of the roof, which impregnation was
most likely to have proceeded from the absorption of the fluid bi-
tumen, much of which, from its levity, would rise to the upper part
of the closely pressed mass of bituminous wood. The flat shivery
state of that which is termed the knotty-coal, as well as of that which
is termed the board-coal, seems to point out, that, after the bitumini-
zation had proceeded to a certain point, this substance had been
deprived of its moisture : the state in which it is found being
exactly that, in which Avood, having suffered such a degree of bitu-
minization, might be expected to be found, after having been per-
mitted to become dry. Nor is it an objection of any force that it
is now found in a moist state ; since, supposing its exsiccation to
have been once complete, and the fermentative operation quite
stopped, no subsequent addition of moisture could be expected to
renew the fermentation, or to soften it so as to render it capable of
uniting in a close mass.

Yours, &c.

LETTER XXI.

THE PURER BITUMENS, THE RESULT OF THE SAME FERMENTA-
TION BY WHICH PEAT HAS-BEEN FORMED.. ..BITUMINOUS FER-
MENTATION IMITATES, IN ITS RESULTS, THE OPERATION OF
SECRETION. ...MINERAL TALLOW, PERHAPS OF ANIMAL ORIGIN
....OTHER ARGUMENTS IN FAVOUR OF BITUMINOUS FERMENTA-
TION.

JH.AVING seen reason to conclude, after examining the subject in
various points of view, that peat is the result of the changes effected
on vegetable matter, during the first stag« of a peculiar fermentation,
it is proper now to proceed to enquire what is the product of that
fermentation in a more advanced stage. But here I must be allowed
to avail myself of the same indulgence, which I was obliged to
crave, whilst endeavouring to ascertain the origin of the former
substance. Here, also, are the same impediments to the obtaining
of positive proofs of the nature of the operation which nature has
decreed to take place ; for here, as in the former case, where the
process is carried on where the eye cannot reach, circumstantial
-evidence, respecting the particulars, and the products, of the opera-
tion, can only be obtained.

Every information which the best authorities have afforded, and
every conjecture which I have been induced to form, from a care-
ful attention to analogy, have led to the conclusion, that the purer
bitumens, such as naphtha, amber, petroleum, asphaltum, £c. are
the products of the same bituminous fermentation, only in a more
advanced stage, as that on which the formation of peat depends.

A considerable weight of evidence is undoubtedly furnished by
the similarity of the products furnished by a chemical analysis of
the peat and the bitumens. That their products by distillation

207

agree exactly in their nature is well known. Some difference, in-
deed, exists in the purity of these products ; but the same peculiar
foetid oil, and the same volatile acid, which are yielded only by
substances of this class, are produced in both cases.

Equally powerful evidence appears to be derived, also, from the
fact of pure bitumen being found existing together with peat, in
such a mode of combination, as will warrant the conclusion, that
the peat has partially passed into a more perfect state of bitumini-
zation, so that a portion of it has become perfect bitumen.

In some parts of Aberdeenshire, Dr. Anderson informs us, there
is found a certain kind of peat-moss, which when formed into peats
in the common way, are found to be more tender and brittle than
usual, so as to break down, during the process of drying, into irre-
gular lumps, called clods. When one of these clods is thrown into
the fire, it soon kindles, and burns with a clear bright flame, much
resembling that which would be produced by a lump of tallow or
butter, in the same circumstances ; these are therefore called creeshy,
i. e. greasy clods, though they discover no degree of unctuosity to
the sight, or smell, or feel. One of these clods continues to flame
for a long time ; and the use that is made of them by the natives
is to throw one clod into the fire at a time, for the purpose of giving
light, and another to supply its place when it is exhausted. This
kind of peat, the Doctor acquaints us, is very rare.

The increased degree of inflammability observed in the peat
which is here described, can only be accounted for by the presence
of bituminous oils ; as the clear bright flame, resembling that of
a lump of tallow or butter, evidently points out. The presence of
any unctuous matter does not indeed appear to be pointed out by
any other sensible characters ; although, perhaps, even its separa-
tion might be obtained by the adoption of proper means.

Monardes, an old Spanish writer on. medicine, says, that in
Collao, a province of Peru, there is a tract where neither tree nor
plant grows, in consequence of the earth being of a bituminous,

208

nature. The Indians obtain from this earth a liquor, useful in
curing many diseases. Their mode of obtaining it is this: — they
cut the earth in turfs, which they dispose on poles, or thick reeds,
in a place exposed to the sun, placing beneath them vessels fit to
receive the fluid ; since the bitumen liquefies, and flows down by
the heat of the sun. The turfs, which are thus deprived of their
bituminous fluid, are afterwards employed as fuel. In this case,
the connection between these two substances appears to be pointed
out decidedly, unless it should be contended, that their existence
thus together might be only accidental. The frequency, however,
with which they are thus found together, the form which the bitu-
men assumes, and indeed the manner in which it is blended with
the peat or fossil wood, strongly declare that the formation of the
bitumen depends on the same process as peat.

Schoockius, as we have already seen, relates, that masses of bitu-
men are frequently found among the peat ; sometimes resembling,
in size and figure, walnuts, eggs, and pine nuts ; and although he
is obliged to acknowledge that undoubted pine nuts were also found
in the same pits, yet these bituminous masses, found in the same
pits with them, were so entirely bituminous, that he could not be-
lieve them ever to have been any thing but a mineral production.

Stelluto, describing the fossil wood of Umbria, mentions a white
resinous substance, which was found along with it, and which bore
the appearance of mastic or frankincense.

Dr. Woodward also mentions, that, along with the hazel nuts and
peat, dug up in the Isle of Wight, were pieces of wood, much im-
paired and decayed, with some small quantities of a black bitumi-
nous matter in its interstices. The Doctor also describes a resinous
matter, which was found lying between the bark and the wood of
some of the trees dug up in Wilmeslow marshes. They call it there,
he informs us, frankincense*.

* Vol. I. Part. II. p. 18.

209

In a considerable stratum of fossil wood, discovered by M. Fon-
taine, between Lyons and Strasburgh, several of the pieces were found
to be incrusted with a pretty considerable quantity of a substance,
which he describes as resembling coarse and imperfect mastic,
mixed with other substances, and adhering so strongly to the wood,
as to be very difficult of separation. Among the fossil wood of
Bovey, as well as among that of Munden, bitumen is also frequently
found.

From the observations already adduced, sufficient surely ap-
pears to warrant the conclusion, that those substances, which are
agreed by all to belong to the class of bitumens, are produced by
a further advance of the same process by which peat is formed.
By attending to the properties possessed by these substances, as
already described, it must occur to you, that although they are
actually of a distinctly different nature, they approach yery nearly,
in their chemical and physical qualities, to the vegetable oils and
resins.

A circumstance here also offers itself to our contemplation, truly
admirable and interesting. A principle of action developes itself,
totally new to our observation, and almost beyond our powers of
comprehension; since it presents to us substances, formed merely
by chemical action, emulating in their nature and appearance some
of those substances, which are only formed by the peculiar powers
resulting from organization.

In the living vegetable, substances are formed, from tasteless
and inodorous materials, by the energies of vegetable life, which
not only strongly affect the senses of taste and smell, but differ
essentially in their properties from the substances from which they
have been formed. So the bituminous fermentation, imitating
the result of the operation of secretion, forms, from a mass of dead
vegetable matter, substances nearly resembling, in most of their
properties, the vegetable oils and resins, which perhaps may be

VOL. I. HE

210

ranked amongst the most highly elaborated products of the vege-
table kingdom.

Accustomed to witness the production of these substances by the
mysterious process of secretion, we find it difficult to conceive
their formation by any process, less complex than that which is per-
formed by the appropriate energies of an organized body. Hence
has arisen much of the difficulty which has occurred, whilst endea-
vouring to account for the formation of bitumen, whether solid or
fluid. Despairing of ascertaining any particular points respecting
its origin, chemists have, until lately, contented themselves with re-
garding it as a mineral production, elaborated in the deep recesses
of the earth, and of course, in situations which yielded no hope of
determining, on what circumstances and principles its formation
depended.

Naphtha, petroleum, and asphaltum, have in general been con-
sidered as substances entirely of mineral origin ; and hence the
names they have obtained of mineral OIL, mineral TAR, and mineral
PITCH. The French chemists have generally adopted the opinion,
that naphtha, and even the other fluid bitumens, are the produce of
a distillation, effected by subterranean fires, by which the more
subtil parts of certain bituminous matters have been raised or sub-
limed ; these particles having been condensed into a fluid form, by
the coldness of the cavities which exist in rocks, and in which they
have become accumulated.

It undoubtedly may appear, at first view, the more easy and
ready way to account for the formation of these matters, by sup-
posing them to be the results of certain subterranean operations,
performed on substances which are natives of those regions ; than
to suppose them to be the results of natural chemical changes,
wrought on substances of the vegetable kingdom by operations
carried on in the mineral kingdom. But a discovery made within
a few years, requires to be particularly noticed here, since it can-

211

not fail to illustrate that particular point, which attracts and most
deservedly claims our attention.

The discovery to which I allude is one which plainly manifests,
that, by the operations of natural chemistry, certain modifications
of the principles of bodies take place, by which substances are
formed resembling, in a great measure, the highly elaborated se-
cretions of an animal body. The illustrious Bacon had declared,
that pieces of flesh might be converted to a fatty substance by the
help of maceration in water. Fourcroy discovered, and his disco-
very has been confirmed and illustrated by the observations and
experiments of several learned and ingenious men in this country,
that the muscular parts of animals, after being buried some time
where water can have access to them, are changed into a peculiar
fatty substance, nearly resembling, in many respects, spermaceti ;
and to which substance he has given the name of adipocire.

Thus we perceive that dead animal matter may by a process
carried on in the mineral kingdom, be converted to a totally diffe-
rent substance, and to one approximating, in its appearance and
nature, to another kind of animal matter, the product of a secre-
tory organization. To repeat the numerous experiments by which
this has been fully ascertained, would be here out of place. The
fact is incontrovertible, and confirms, by analogy, the opinion,
that the organized matters of vegetables are likewise susceptible
of a correspondent change, if placed under appropriate circum-
stances.

Another substance, found among the peat, requires also to be
spoken of, particularly in this place ; since it appears to me* that
the ambiguity which obscures its origin is likely to be best
removed, by the discovery to which I have just called your atten-
tion.

This substance has been hitherto called Mineral Tallow, and is
thus spoken of by our justly celebrated mineralogist, Mr. Kir wan;

212

This is a substance very rarely met with, and therefore very im-
perfectly known ; it was first found by some peasants, on the coast
of Finland, in the year 1736. Afterwards a similar substance oc-
curred in one of the Swedish lakes ; and, lastly, Mr. Herman, a
physician at Strasburgh, discovered a similar substance in the
water of a fountain of that city. He describes it as being white,
having nearly the resemblance of tallow ; feeling greasy, and stain-
ing paper, as tallow does. It flames, he observes, with much smoke,
and leaves a pretty light coaly matter. It is brittle like tallow, but
its specific gravity is considerably less *.

Not unlike to the substance, thus described by Mr. Kirwan, is
that which Mr. Jameson speaks of as having been found in the
peat-mosses of Scotland -)-.

A substance similar to that which is here described I have been
shown by Mr. Mawes, of Tavistock-street, in his excellent collec-
tion of the bitumens of Derbyshire ; in which place this specimen
had been found.

Humbold, in a letter to Van Mons J, mentions, that he had
converted the phallus esculentus into a substance resembling tallow,
by means of the sulphuric acid, and had also made soap of it.
Hence Mr. Jameson is induced to ask — May not the mineral tallow
of peat-mosses be a species of fungus, altered by some natural
operation similar to what we have here mentioned.

The close resemblance which seems to subsist between this sub-
stance and the adipocire, the want of proof of its vegetable origin,
and the rarity of its occurrence, which indeed corresponds with
that of animal matter in peat bogs, incline me to imagine that its
origin may be attributable to some animal remains, which chance
has deposited in these parts, and which, exposed to the action of
water, has suffered a change into adipocire. This opinion, I think,

* Elements of Mineralogy, vol. ii. p. 47. f Mineralogy of the Shetland Isles, p. 156.
$ Annales de Chymie, vol. xxii. p. 64.

213

is rather countenanced by the instances which occur, in the writings
of those who have described the peat pits of various parts of the
world, of the existence of animal remains in these subterranean
situations.

Thus Dr. Leigh, in his History of Cheshire, relates, that he saw,
five yards within the marie, the skeleton of a buck, as standing
upon his feet, with the horns on his head, which, the Doctor says,
at the time of his writing, were preserved at Ellels Grange, near
Lancaster. He likewise informs us, that eight yards within the
marie, at Larbrick, near Preston, in Lancashire, the entire head of
a stag, of an enormous size, was found. He also mentions, that
the head of an hippopotamus was found under the moss in Lan^
cashire.

Mr. A. de la Prime says *, about fifty years ago, at the very bot-
tom of a turf pit, was found a man lying at his length, with his
head upon his arm as in a common posture of sleep, whose skin
being as it were tanned, by the More water, preserved his shape
entire ; but within, his flesh, and most of his bones, were consumed
and gone ; an arm of whom, Mr. de la Pryme adds, one of the
workmen cut off, and brought home to his master, which is now in
the possession of my honoured friend Dr. Nat. Johnson. In the
clay lying over the peat, which was lately dug through, in forming
the wet docks in the Isle of Dogs, the bones of horses and oxen
were also found.

One more instance remains to be adduced of the formation of
oily matter from substances possessing nothing of an oily nature,
merely by the aid of a chemical process. In referring to this, I
trust a fair opportunity will offer itself of determining whether the
formation of naphtha, petroleum, amber, or, in a word, the bitu-
mens, may be attributed, or not, to a change induced in vegetable

'* Phtlosoph, Trans, vol.

matter by a peculiar species of fermentation. The change, to which
I allude, is one which takes place in the product of the vinous fer-
mentation ; and which seems to point out a strong analogy between
that species of fermentation and the process of bituminization,

In the vinous fermentation, during the stage of sensible effer-
vescence, as has been already observed, a considerable quantity of
oxygen is dissipated, in a gaseous form, in combination with a por-
tion of carbon, sufficient to form with it carbonic acid gas : this
escape of these two principles, leaving, we may suppose, an in-
creased proportion of hydrogen in the remaining mixture. In the
next stage of the process, that which is accomplished in the closed
vessels, part of the remaining oxygen, which is denied the oppor-
tunity of thus liberating itself, with carbon, in a gaseous form, en-
ters into another kind of combination with the same principle,
and forms the acid of the wine ; which, according to the opinion of
Fourcroy, is the malic acid : whilst the hydrogen, uniting with ano-
ther part of the oxygen, and holding a portion of carbon in solution,
forms with it the spirituous or intoxicating part ; the whole forming
WINE. This vinous fluid being subjected to the distillatory pro-
cess, a new arrangement of these principles ensues : and a combi-
nation of them, in which hydrogen is highly predominant, comes
over in the form of ALCOHOL,

If to this alcohol an acid, but particularly the sulphuric, be
added> then a substance will be separated, by distillation, the most
light and inflammable of all fluids, termed ETHER; and which, in
consequence of its possessing these properties of the purest fluid
bitumen, is often described by the same name, naphtha. But if
the distillation be continued beyond this, a heavier and less vola-
tile fluid comes over, containing a larger dose of carbon ; and is
called, from its oily appearance, the oil of wine ; a gas being also
at the same time separated, which, on being mixed with the oxy-
genized muriatic acid gas, actually produces an oil possessing

215

peculiar properties. Should the oxygenized muriatic be the acid
which is employed from the first, an oily matter is generally the
result of the distillation : and if the acid be employed in a large
proportion, a white, opaque greasy substance, of the consistence of
half-melted tallow, will be focmed.

To enable you to judge of the propriety of considering the change
thus produced as analogous with the bituminization of vegetable
matter, I will briefly state the more generally received opinions,
respecting the circumstances on which this conversion of alcohol
into ether depends. Laudet and Dabit found, that the addition of
oxygen was necessary to the formation of ether ; and they disco-
vered, that by employing the oxide of manganese with the sul-
phuric acid, this acid was not decomposed, as would otherwise
have been the case ; but, that the oxide was deprived of a part of
its oxygen, and a greater quantity of ether than usual was obtained;
no gas coming over, and no charcoal being deposited during the
distillation. They therefore concluded, that ether contained a
smaller pioportion of hydrogen, and a greater proportion ot oxygen
and carbon, than alcohol. Fourcroy and Vauquelin, on the other
hand, supposed ether to contain a greater proportion of hydrogen
and oxygen, and a smaller proportion of carbon, than alcohol.
Thus differing in their opinion as to the proportion of the respective
principles ; but agreeing, that ether is a substance formed by a new
combination of the same principles of which alcohol is composed,
but in different proportions *..

* May not the formation of ether be still better understood by adverting to one im-
portant fact, that the solution of carbon in hydrogen is promoted by the presence of
oxygen, as is the case in carburetted hydrogen gas ? May not, therefore, the addition
of the acid or the oxide to the alcohol, by furnishing an increased proportion of oxy-
gen, enable the hydrogen to retain more of the carbon in solution, and thus produce
an approximation to an oleous state ? In confirmation of this opinion, it is to be consi
dered that, by the addition of merely oxygenized muriatic gas to carburetted hydrogen

216

Having thus furnished you with the particulars of that chemical
process by which an oil is formed from substances which would not
d priori have been expected to yield it, we will now endeavour to
ascertain how far that process resembles the presumed process of
bituminization. In the first place, then, the substances acted upon,
by the supposed bituminous fermentation, as well as by the vinous
fermentation, are the same — dead vegetable matter. Secondly, as
in the vinous fermentation, so in the bituminous fermentation, a
peculiar acid and a peculiar combustible substance is formed;
those of each process resembling each other in their component
principles ; this resemblance being particularly close between the
combustible substances resulting from each process : each possess-
ing a high degree of levity and inflammability ; each being formed
of hydrogen, combined with a large proportion of carbon and of
oxygen ; and each manifesting, that the principles of which they
are composed are not in a very intimate state of union.

I am anxious, before I conclude this letter, to place before you
some of the reasons which have induced me to suppose the ligneous
substance to be that part of vegetables which is most particularly
acted on, by the species of fermentation which I have assumed ;
as well as to point out to you a circumstance, which, in my opinion,
yields strong, I had almost said internal, evidence of the necessity
of such a species of fermentation.

gas, an oily fluid is formed; and that by the employment of the same acid, in a more
powerful manner, an actual tallow like grease is produced. Another consideration,
which seems to corroborate this opinion, of the different steps of this progress to an ole-
aginous state, depending on certain added proportions of carbon, combined with oxy-
gen, is, that oil itself, the ultimatum of this process, holds so considerable a portion of
carbon, that this principle constitutes a large proportion of every one of its products^
which are carburetted hydrogen, carbonic acid, and charcoal; whilst the quantity of
oxygen which it contains is also so great that it manifests a degree of acidity, in a very
short time, merely by the addition of what it attracts from the air.

So generally is the ligneous substance diffused through the vege-
table system, as to render it, perhaps, the most abundant of the
compound constituents of vegetables. It not only forms almost
the whole of the bulk of the trunks and boughs of trees, and shells
of fruits ; but it also forms a great part of the husks, and lanugi-
nous coverings of seeds, as well as of the epidermis of leaves, &c.
The quantity in which it exists agrees therefore in the abundance
of bitumen which seems to be yielded by that species of fermen-
tation, to which I have presumed that vegetables are subject; and
it is also worthy of notice, that the substances, which have been
just described, as containing a predominating proportion of the
ligneous part, are those substances which are most frequently found
in a bituminous or in a mineral state.

The contemplation of nature teaches, that there exists a regular
system of dissolution and renovation, through all her works ; and
that there are certain laws, according to which, substances are forced
to quit one form of existence, and take on another ; their princi-
ples entering into new combinations, and forming other substances
equally necessary in the ceconomy of nature. Thus is constituted the
never-ending chain of varying existences, in which, though each
link differs from the rest, yet such is their symmetry and proportion,
that they form a whole, in which beauty and utility are eminently
conspicuous. But when we view the chemical history of the lig-
neous matter of vegetables, a link appears to be lost, and the chain
broken ; for whilst other substances yield either to the vinous, or
to putrid fermentation, the ligneous, we are told, seems to resist all
nature's efforts to force it into a new mode of existence. So re-
fractory does it appear, that it is esteemed the most insoluble and
unchangeable of all vegetable substances. If wood be exposed in
a close vessel to the destructive action of fire, so little of the lig-
neous substance is lost, that a charcoal is left which still retains

VOL. I. FF

218

the form of the piece of wood it originally composed. This expe-
riment serves also to show that the ligneous substance contains
the greatest quantity of carbon of any vegetable substance ; and
that it is therefore well fitted for the formation of substances, so
abundant in carbon, as is coal, and every species of bitumen. Even
the concurrent influence of air and water effects scarcely any
change on it ; and it is said to resist, so absolutely, every known
kind of fermentation, as to be supposed to be indestructible, except
by insects. Reasoning, then, on the chemical nature of this sub-
stance, we are led, by analogy, to conclude, that, as in every other
case, so here, nature has appointed some agent, by which this ap-
parently refractory substance shall be made to pass into new com-
binations. Such an agent, the bituminous fermentation appears to
be ; and every observation warrants the conclusion, that it is the
ligneous part of vegetables which is the chief substance susceptible
of this peculiar change.

Yours, &c.

LETTER XXII.

OF THE ORIGIN OF THE PURER BITUMENS.... NAPHTHA. ...PETRO-
LEUM....MINERAL TAR.. ..MINERAL PITCH. ...ASPH ALTUM.... AM-
BER... .MELLITE.... JET AND CANNEL COAL.

1 HAT the purer bitumens have had the same origin as peat — that
they have been produced from the same species of matter, and by
the same natural process — and that they differ from it only in
having been separated by percolation from the grosser parts, seem

219

to be proved, by the frequency with which they are found together,
but more particularly, by the exact agreement observable in their
chemical properties. In perfect agreement with peat, as well as
with, as we have just remarked, the products of the vinous fermen-
tation, the purer bitumens are composed of hydrogen, carbon, and
oxygen ; but, as might have been expected from the circumstances
under which their formation has taken place, no escape of the vola-
tile principles having been admitted, the new compound appears
to be the result of a high degree of concentration of these princi-
ples. The great degree of inflammability, possessed by all the
bitumens, manifests the large quantity of hydrogen which they con-
tain ; and the blackening of the clear and colourless naphtha, on
exposure to the air and light, shows the hydrogen to be saturated
with carbon.

I cannot quit this subject, without pointing out the great obli-
gations which the lovers of chemistry owe to Mr. Hatchett, for his
ingenious observations on the nature of bitumens, and of the
changes which they undergo. The opinion which I have above
adopted, respecting the deposition of carbon, and the consequent
disposition to blackness in petroleum, asphaltum, &c. originated
with that gentleman, and is thus most concisely and happily ex-
pressed by him. "The progressive changes of naphtha into petro-
leum, mineral tar, mineral pitch, and asphaltun*, appear to be
caused by the gradual dissipation of part of the hydrogen of the
bitumen, and the consequent developement or disengagement of
carbon. Hence, I am inclined to believe, arise the changes of
colour, the degrees of inspissation, and the increased proportion
of carbon, found in those substances by chemical analysis I would
be understood, however, to mean that the carbon is only relatively
increased, in respect to the other ingredients, in a given quantity
of these bitumens, and that it predominates in proportion to the
dissipation of a certain portion of the hydrogen, which was origi-

nally necessary to the forming of the > bitumen in conjunction with
the carbon *."

The origin of AMBER, the next bituminous substance which de-
mands our attention, is an enigma, the solution of which appears
to be fraught with considerable difficulties. The analysis of this
substance, as has been already seen, manifests plainly that it pos-
sesses, in every respect, the chemical properties of bitumen. Am-
ber, exposed to the fire, liquefies if the heat be strong, softening
and bubbling, without running into drops ; which circumstance
distinguishes it from the resins. When inflamed, it diffuses a thick
smoke, with a pungent odour. Its flame is yellow, but variegated
with blue and green. It leaves, after combustion, a black shining
coal, which yields by incineration a very small quantity of earth,
mixed with a very slight proportion of iron. From these proper-
ties we should therefore be led, without the least hesitation, to seek
for its formation in the subterranean laboratory of nature ; but for
its bearing accidental, but unequivocal marks, of having existed,
during some of the stages of the process, by which it has been
formed, either actually on, or very near to, the surface of the earth.

Naturalists have by no means agreed in their opinions respecting
the origin of this substance. Theophrastus speaks of amber as a
stone, dug out of the earth in Liguria, and which possesses a power
of attraction. Sir John Hill, in his notes on this passage, gives it as
his opinion that it is, as he says, the best of the modern writers seem
certain of its being, a mere native fossil -j-. Dioscorides thought it
to be an exudation from the black poplar. Pliny, who particularly
noticed this substance, supposed it to have run from the trunks of
trees, resembling pines, in the same manner as rosin is known to flow
from the pines, and gum from the cherry-trees ; and hence he ima-

* PhilosophicalJournal, vol. ii. p. 203.

t Theophrastus onv Stones, translated by John Hill, M. D. p. 133.

221

gined that it derived its name Succinum, from succus a juice. This opi-
nion he thought was confirmed, by the smell it yields on being rubbed,
and the bright flame with which it burns. According to the learned
annotator, in the edition of Pliny by Dalechamp*, in that part of
the world which appears to yield amber there are no trees which
can be termed resiniferous ; but he observes, along the northern
shore there is certainly a kind of yellow bitumen, as well as a black
kind, to be found about Auvergne, and that from it proceeds a
yellow naphtha, as well as from the other is produced a black
petroleum. When the bitumen thus flows, soft and even liquid,
from its spring, it catches, retains, and incloses whatever it may
meet with. Flowing thus, he supposes it to be carried into the sea,
where, by the saltness of the water, by agitation, and great length
of time, it becomes hardened, as likewise takes place with asphal-
tum, thus becoming amber; and, being driven by the winds, is
thrown on the shores opposite to where its springs exist. Agricola
had no hesitation in placing this substance among those of the mi-
neral kingdom, considering it as a bitumen, from which he knew
that peculiar products might be obtained by chemical operations.
Hartmann erroneously supposed it to be a stone of the precious
kind, and therefore considered it as one of the gems. Some mo-
derns have adopted the old opinion of its being a vegetable pro-
duction, supposing it to be the gum or resin of the poplar tree.
This opinion has been corroborated by the similarity, in many
respects, between this substnnce and copal, which is positively
asserted to be a concrete juice of a tree (rhus copaliumm) of New
Spain ; but this substance being neither soluble in water, like gums,
nor in spirits of wine, like resins, has by many been also supposed
to be of mineral origin. Girtanner even considered amber as an
animal production, and supposed it to be formed by the large red
ant (formica rufa LINN.) These ants, he observes, form hills, which

* Lib. xxxvii. cap. iii.

222

are sometimes six feet in diameter, and inhabit the old pine forests ;
which forests, or at least the spots where they have been, are, he
says, the places where the amber is chiefly found. His conjecture
is founded on a substance having been found in the nests of these
insects, of the consistence of honey, or of half melted wax ; hav-
ing the yellow colour of common amber, yielding the same pro-
ducts by chemical analysis, and acquiring the same degree of
hardness by remaining some time in a solution of common salt. It
appears, from his observations, therefore, that we should consider
amber as a vegetable oil, rendered concrete by the acid of the ants ;
since wax, according to the experiments of La Metherie, is vege-
table oil hardened by the acid of the bee.

But the circumstance, perhaps, from which may be deduced the
most powerful arguments against this substance being of animal
origin, and also against its being entirely of a vegetable nature, is its
being found in such large quantities at a considerable depth in the
earth. From the account of Junker, which was afterwards copied
by Neuman ; and from that which is delivered by Hoffman, we learn
that the king of Prussia gave orders that search should be made for
the subterranean beds of this substance. Directed, most probably,
by those marks which point out a spot particularly rich in bitumen,
and which are very frequently observable in that part of the world,
the required examination was commenced. After getting through
the ordinary superficial stratum, they found a bed of sand, beneath
which was a stratum of clay. On digging through this, a stratum
appeared, which seemed to be formed of wood, very old and de-
cayed, but which very readily took fire. This stratum of bitumi-
nous wood they generally found immediately over a stratum of
pyrites, which yielded sulphate of iron very copiously ; immedi-
ately below this was found a stratum of sand, the real matrix of
the amber, in which this bitumen was most plentifully found, scat-
tered in small pieces, and sometimes even accumulated in heaps.

223

Hoffman supposes the amber here to have been formed by the oil
of the wood flowing from subterranean heat, like the oil of petro-
leum, and passing through the bed of pyrites, which lay under-
neath, thus becoming impregnated with the acid of the vitriol,
and thereby obtaining its peculiar nature and appearance.

The opinion of Neuman very nearly agreed with that of Hoff-
man, he supposing the amber to be formed by the combination of
the oil of petroleum with a fine earth held in solution by the acid
of vitriol.

The frequent existence of small insects, and of vegetable matters,
in the midst of its masses, presents a considerable difficulty to
those who consider it entirely as a mineral production. Breynius,
however, in the paper already mentioned, remarks that the pre-
sence of these foreign matters is not inconsistent with the idea of
its subterranean formation ; he observing that many insects pene-
trate beneath the surface of the earth, to deposit their eggs, to
change their skin, or to relinquish life ; and that vegetable matters
are also carried beneath the surface by various insects, who thus
retire into the earth. But when it is considered that insects make
their way but a little depth below the surface, and that the amber
is found at considerable depths, there seems but very little proba-
bility that these substances had become imprisoned in this way.
Besides, the substance which appears to be the most common matrix
of amber, is bituminous wood, and very unlikely to be thus visited,
it being a circumstance deserving of notice, not only in reference
to this particular circumstance, but as an important general fact,
that bituminous impregnations are so unfriendly to animal life,
that no living creature has ever been found in peat, or in any otner
stratum of the bituminous kind.

This particular circumstance has been remarked by several of
the most intelligent writers on the history of these substances.
Nor do I know of any contradiction to their observation, except

224

in a solitary and very anomalous circumstance related by Lord
Cr.omartie, in the Philosophical Transactions *. By his lordship's
account we learn, that in a moss near the town of Eglin in Murray,
though there is no water which communicates with the moss, yet
for three or four feet of depth in the moss there are little shell-fish,
resembling oysters, with living fish in them, in great quantities,
though no such fish are found in the adjacent rivers, nor even in
the water-pits in the moss, but only in the solid substance of the
moss. Dr. Darwin considers this as a curious fact, which not only
accounts for the shells which are sometimes found on the surface
of coals, and in the clay above them, but also for the thin stratum
of shells which sometimes exists over iron ore.

The presence of light vegetable matters, and of small insects,
such as flies, certainly at the first thought, appears to yield in-
disputable evidence of the truth of that opinion which supposes
amber to have originally been the gum or resin of a tree ; and
•which, whilst adhering to the tree, had thus caught these substances,
which a continued effusion of the same matter had thus involved.
But supposing this to have been the case, and that this substance
had become buried in the earth, still its bituminous nature remains
to be accounted for. It once indeed appeared to me as far from
impossible, that the vegetable gums or resins inclosed in the mass
of vegetable matters passing into the state of bitumen, might with
them be pervaded by the fermentative influence ; and, as actually
happens with other vegetable matters, lose little if any of their
original form and appearance. But maturer consideration has
shown that the opinion of the learned annotator on the works of
Pliny is that which best accords with all those phenomena, which
appear so contradictory, if regarded in any other point of view.

The opinion of Mr. Dalechamp, as we have already seen, is, that

* Philosophical Transactions, N° 330.

225

amber is a bituminous substance, which, exuding in a soft and
nearly fluid state, from clefts in the earth where bituminous strata
exist, has, during its soft and tenacious state, inviscated and en-
veloped these different extraneous bodies. Against this opinion
there does not exist any objection, since it is not at all difficult
to conceive, that amber may be the solid form which the transparent
fluid naphtha assumes from inspissation under certain circum-
stances, as asphaltum may be considered to be the result of a similar
change effected on petroleum.

It is true that I have considered it as probable, that petroleum,
an opaque and dark-coloured substance, is naphtha changed by
having suffered a degree of inspissation ; it may therefore appear
contradictory to suppose a transparent substance like amber to be
likewise the result of the inspissation of naphtha. But, as has been
already remarked with respect to the probable change of naphtha
into petroleum, the change is not effected merely by inspissation,
but by a separation and a change in the proportion of the consti-
tuent principles, hydrogen having escaped and charcoal having
been deposited. But most certainly there is nothing to contradict
the supposition that naphtha is also susceptible of a simple evapo-
ration, and consequent inspissation, similar to that which the fixed
oils undergo, in consequence of the long-continued application of
a gentle heat.

If amber were gum or resin which has undergone the change of
bituminization, the matters which it contains should certainly also
have suffered a similar change. In the few pieces in my own pos-
session, as well as in all others which I have seen, except in one
instance, which I shall presently notice, the insects appear not to
have suffered the least change, even in their colours, which surely
must have been the case, had they been macerating in the softened
mass which contains them, during such a change ; although, from

VOL. i. G G

226

the difference of their nature, they might be entirely exempt from
the other effects of the bituminizating process.

In one specimen, which I possess, containing vegetable matters,
the little fragments of moss, and the other particles which are so
small as not to furnish the means of judging to what plants, or
even to what parts of plants, they belong, do not appear to have
suffered the least change, nor to have made the least approach to
transparency, excepting one or two pieces, in which it may be
readily accounted for, by their extreme thinness and natural prone-
ness to pellucidness. Not having suffered that change, which this
hypothesis supposes the containing mass to have undergone, it
seems fair to conclude, that these matters must have been intro-
duced after this particular process had been accomplished in the
amber itself, and are therefore preserved, like the insects, in the
same state as when first entombed.

Let us not refuse instruction whenever it is offered to us, and
especially when, by duly attending to it, we may escape the sus-
pended lash, necessarily held in readiness to check the prompt and
presumptive theorist. The specimen of amber to which I have
alluded, besides substances decidedly vegetable, and others too
equivocal to determine whether they are parts of vegetables or of
insects, contains two flies. One of these appears to be in as per-
fect a state of preservation as when living ; the legs being collected
nearly in a point, and stretched to their length, as though the
flowing bitumen had secured the imprisonment of the little captive,
during its active exertions to raise himself from the treacherous
surface. The other, on the contrary, appears to have lost its na-
tural colours, and possesses very nearly the transparency, which is
very considerable, of the amber itself; as if it had undergone a
similar change with the substance which contains it. If it had
been a leaf instead of a fly, what would have become of our pro-

227

posed hypothesis ? — But might it not have been only the thin and
wasted remains of a dead fly, the transparency of which has been
increased by its becoming filled by the bright and clear bitumen ?

Having hazarded the conjecture that amber has existed, as a
bitumen in a fluid state, and that the foreign substances it contains
were introduced in it whilst it was in that state, it may be expected
that some instances should be adduced of its having been found in
an intermediate state between that of fluidity and that in which
it is supposed constantly to exist.

But it must be considered that the characteristic physical pro-
perties of amber, such as yielding a peculiar odour, and becoming
attractive by friction, depend on its indurated state, and must
therefore be sought for in vain, in an inferior state of inspissation.
To ascertain, with precision, therefore, from what species of liquid
bitumen it is derived, may be impossible ; since we are reduced,
whilst seeking for the analogous fluid bitumen, to trace it by the
aid only of such physical properties as colour, degree of trans-
parency, &c. which are common to both states. By these marks,
perhaps, if the substances had been examined with a view to that
inquiry, some analogy might have been discovered between amber
and those bituminous masses found by Stelluto, and those said to
resemble mastich and frankincense, which are described by Dr.
Woodward and Mons. Fontaine, and which were found even incor-
porated with fossil wood, with which substance, we have already
seen, amber is found generally associated. Were such specimens
again to be found, it would be, certainly, highly desirable to ascer-
tain whether, by continued exposure to a slightly increased degree
of temperature, or by long keeping, it would acquire the hardness
and other properties of amber.

A specimen of elastic bitumen from Castleton, in Derbyshire,
which I possess through the kindness of Mr. Mawes, shows that
this variety of bitumen, in a soft state, may possess the colour as

228

well as the transparency of amber. It exists in a piece of lime-
stone, to which it adheres very closely. Its transparency is almost
that of the clearest amber, and the colour, which is most generally
diffused through it, is of a deepish yellow, just such as would be
conceived from the term amber-yellow, being tinged also in dif-
ferent parts with a brownish red. Its degree of softness is such,
that it yields to the slightest pressure, recovering itself, however,
on the removal of the pressure, with such a degree of elasticity,
as undoubtedly authorizes the placing it among the elastic bi-
tumens.

The elastic bitumens, as we learn by the valuable observations of
Mr. Hatchett, may, by being melted, be deprived of their elasticity,
and thus might the specimen here alluded to be reduced to the
more common state of bitumens ; and probably, by a well-managed
inspissation, might be made to assume a solid form, without its
transparency or colour being at all thereby impaired. In this
state, it would probably become attractive by friction ; which
property, taken in conjunction with its colour and transparency,
would necessarily render its resemblance to amber very close.

By what has been here said, I do not intend to imply that
such a substance would be actually amber ; since, perhaps, the
formation of amber may depend on peculiar circumstances at-
tendant on its inspissation ; and most particularly on some pecu-
liar modification of the oxygen contained in the bitumen from
which it may proceed.

Within these few years a substance has been found among the
bituminous wood of Thuringia, which has been named, from its
colour, HONEY-STONE (honigstein) by Mr. Werner, and MELLITE
by other naturalists. It is of rather a dark honey colour, and, from
its resembling amber also in colour, it has been thought to be that
substance in another form. It is usually crystallized in small octa-
hedra, the angles of which are frequently truncated, and some-

times curvilinearly. Sometimes its crystals are dodecahedral. and
approaching to the rhomboidal. Its hardness is such as yields
easily to the knife, its transparency considerable, its fracture con-
choidal, and its specific gravity 1.666. Like amber, its crystals
become electric by friction, but not unless previously insulated.
It is insoluble in water, and therefore communicates no taste to it.
Being heated in a retort, it is decomposed, and yields a bituminous
and empyreumatic water, carbonic acid, and a concrete volatile
salt; a carbonaceous residuum being left. When placed on burn-
ing charcoal, or in a heated crucible, it burns like combustible
vegetable matter ; leaving a greyish white matter, which has all the
characters of alumine, mixed with a small portion of lime. This
substance therefore appears to be composed of alumine, bitumen,
a small portion of lime, and a peculiar acid, which resembles in
many of its properties the oxalic acid, but differs from it materially
in others. This acid is decomposed very speedily by heat, evapo-
rating in a dense smoke ; and by distillation yields a considerable
quantity of carbonic acid. When the constituent parts of this
substance are considered, with the situation in which it is found, and
the substances with which it is associated, there can be but little
hesitation in admitting it to be produced by the subterranean de-
composition of vegetable matter, and therefore to belong to that
class of natural productions of which we are here treating. The
appearance which this substance presents may be pretty correctly
known by reference to the representation of it, Plate I. Fig. 2.

The bituminous nature of JET is indisputable, it being plainly
evinced both by its chemical and physical properties. Indeed it
often manifests so exact a resemblance, in every respect, except in
its colour, to arnber, as to have occasioned it to be named, as has
been already remarked, black amber. The blackness which distin-
guishes it has never yet been satisfactorily accounted for, and in-
deed offers to our consideration a question difficult of solution.

230

The learned Wallerius and the celebrated Fourcroy have contented
themselves with considering jet merely as indurated asphaltum ;
whilst others have been satisfied with describing it, with coal, as
bitumen, altered by exposure to the action of certain mineral acids.
Mr. Hatchett, indeed, in that most valuable paper to which I have
already referred, is much more explicit in his account of this sub-
tance, and, indeed, makes the only near approach towards explain-
ing the cause of its blackness, I am inclined, he says, to believe,
that it is neither asphaltum nor coal, but an intermediate substance,
which may be regarded, as the first gradation from the simple bitu-
men into those which are compound. The matter of asphaltum
undoubtedly enters into it in a large proportion, and has conse-
quently stamped several of its characters upon it ; but the increase
of carbon, and of the extraneous or earthy matter which is inti-
mately mixed, or rather combined with it, has had so much influ-
ence, that the characters of coal are also in some measure apparent,
and are rendered the more striking by the similarity of certain local
circumstances which attend these two substances*.

Whilst endeavouring to account for the darkening of petroleum,
it has been assumed as probable, that the dark matter is formed by
the abstraction of a portion of hydrogen, occasioning a propor-
tionate deposition of carbon ; and that the colour would vary with
the degree to which this process accompanied that of inspissation.
By the extension of this principle, it seems the blackness of jet
may be also accounted for, supposing that, during the inspissation
of the bitumen, circumstances the most favourable to the separa-
tion of the carbon have occurred.

Jet, then, I conclude to be a bituminous substance, containing
a considerable proportion of carbon: its levity, its conchoidal
fracture, and its glassy lustre, existing in proportion to its freedom
from any extraneous intermixture, and to the quantity of unchanged
bitumen it still retains.

* Philosophical Journal, vol. ii. p. 240.

231

That jet is a pure bitumen, differing from amber, only in its having
undergone some process by which its colour has been changed,
will appear still more probable from the following relation of the
learned Dalecamp, in his annotations on the Natural History of
Pliny *. " I have/' he says, " a piece of jet, which, beyond all
doubt, has been digested for many ages in the bowels of the earth.
It was dug out of the quarries near Narbonne ; one half of it is
black, and the other yellow, resembling amber."

Having ventured to assume that jet is bitumen changed by a
particular process ; it may be expected, that as bitumen appears in
different forms, so should jet : — and this is the case. According to
the form of the substance from which the bitumen derived its origin,
will, frequently, be the form in which the jet appears. If the jet
has proceeded from a piece of detached bitumen, which had at-
tained a state of softness approaching even to fluidity, such as
that in which amber must, at one period, have existed ; its surface,
and the whole of its external form, will yield an appearance plainly
declaratory of the very soft state in which it has existed.

But should it have originally been wood, which during its bitu-
minization had made but little approach to liquefaction, the fibrous
texture of the wood may perhaps be still discernible. This indeed
frequently happens ; and sometimes the external part will display,
not merely the texture, but the general form, and even the colour,
of wood. A specimen of this kind is depicted, Plate I. Fig. 4.
On the flat surface of this specimen the fibrous texture of the wood
appears exceedingly well marked ; whilst, at the end, the conchoidal
fracture, the jet black, and the glassy lustre, sufficiently evince its
bituminous nature.

Jet has obtained a distinction, among collectors, into English or
foreign ; they being guided, in making this distinction, merely by its

* C. Plinii Secundi Historise Mundi, lib. xxxvii. Colonise Allobrogum, 1615. lib.
xxxvii. p. 733.

232

weight. Thus that which swims on water they describe as English,
but that which is heavier they suppose to be foreign. The grounds
of this distinction are, that the pieces of jet found on the English
shores are thus light, whilst the handsomer specimens brought from
France and Prussia are more ponderous : the fact, however, is, that
the pieces of jet found on our shores are also chiefly foreign ; and,
having been detached from the strata of the opposite shores, have,
in consequence of their lightness, floated here on the waves of
the sea.

The transition of jet into c ANN EL COAL is frequently very diffi-
cult of detection ; the difference between the two substances seem-
ing to depend entirely on the quantity of foreign earthy matters
which have been introduced into the fluid bitumen.

One mark of distinction between jet and cannel coal, perfectly
accords with the opinion which I have offered respecting their
formation. Jet, which is pure bituminized vegetable matter, some-
times, as has been already remarked, displays not only the general
form, but the texture and colour, of wood, manifesting that it is
purely bituminized wood, some parts of which, and these generally
the cortical, having resisted the influence of the fermentation more
than that part which is more generally considered as wood. But in
cannel coal, which has been in so fluid a state as to have admitted
the intermixture of earthy matters, seldom any thing of this kind
appears. Impressions of various vegetable substances are indeed
often displayed on its surface, possessing such a degree of correct-
ness and sharpness, as plainly to evince its having been in a very
soft state when the impressing substance was applied to it; but
these extend no deeper than the surface, its substance or texture
seldom pointing out the substance from which it originated. Re-
presentations of the appearances which thus offer themselves to our
yiewyou will see depictured, Plate 1. Fig. 6 & 7.

Yours, &c.

233

LETTER XXIII.

/

OPINIONS RESPECTING THE FORMATION OF COAL. ...EARTH IM-
PREGNATED WITH PETROLEUM, THE OPINION OF BUFFON
AND GENSANNE... .OPINION OF SIGN. ARDUINO....OF DR. BUT-
TON 'AND PROFESSOR PLAYFAIR....OF MR. WILLIAMS. ...OF

MONS. TINGRY....OF DR. DARWIN. ...OF MR. KIRWAN....OF MR.
HATCHETT....OF MONS. PATRIN....OF MONS. FOURCROY.

AMONG the humiliating proofs of our limited powers of inquiry,
there are few which are more striking, than that which is manifested
by the inefficiency of our investigations relative to coal. Respect-
ing the origin of this substance, so plentifully bestowed on us for
Our daily use, and consequently continually subjected to the im-
mediate examination of our senses, the most widely different opi-
nions have been held ; and by those, too, who have been the most
competent to form a proper judgment. Even with that theory
which has been the latest promulgated, by a gentleman whose ex-
traordinary knowledge in mineralogy and chemistry stamps a high
degree of authority on every opinion he adopts, I am under the
necessity of expressing my dissatisfaction.

This circumstance is the more unpleasant, since the observations
which led to the objections to this ingenious theory, have also led
to the adoption of an hypothesis, which, although sufficiently seduc-
tive to hold my judgment captive, may be found, by the more
discerning, to posses much less probability than those opinions to
which it is opposed. To enable you to form a judgment on this
subject, I shall proceed to place before you those opinions which
have been most generally adopted, and such objections as seem to
affect their validity.

VOL. I. H H

234

The specific gravity and hardness of some species of coal, have
procured coal in general to be distinguished, by some, by the term
of stone-coal. Struck by the predominance of these qualities, and
perceiving also the great quantity of bituminous matter contained
in coal, this substance has been considered, by some chemists of
considerable knowledge and abilities, as being an earth, or rather
a stone of the argillaceous genus, which has become impregnated
with petroleum. The impropriety of thus considering it must,
however, at once appear, when it is recollected, that chemical ex-
amination has shown, that, in common coal, the proportion of earth,
to that of carbonaceous and bituminous matters, is so very trifling,
as seldom to exceed a thirtieth part of the mass.

In some instances, indeed, such as the slaty cannel coal, from
Ayrshire, in Scotland, analyzed by Mr. Kirwan, and the stony coal
of Macinaia, the analysis of which has been given by Signor Fa-
broni, the earthy parts have amounted to a fifth, and even one half
of the whole mass. But these are substances which deviate so
much from the characters of coal, as not to be admissible into the
same class with it, but should be rather considered as varieties of
slate, lime-stone, &c.

Others have been of opinion, that coal is entirely of marine
origin; and formed by the fat, and various unctuous matters, which
have proceeded from the innumerable tribes of animals which have
peopled the ocean. This mass- of matter is supposed to have accu-
mulated, and at last to have become covered by various strata, in
consequence of the different changes which the surface of the earth,
and the receptacles of the waters of this globe, have experienced.
To show the improbability of this hypothesis, it is, perhaps, suffi-
cient to remark, that the levity of .s.uch substances could never
admit of their accumulation at the bottom of the sea, which, ac-
cording to the principles of this theory, must be supposed to have
taken place.

235

Dr. Hutton ingeniously laboured to establish his hypothesis of
the succession of worlds by a system of revolutions, occurring at
regular periods, each successive period of existence being, accord-
ing to our measurement of time, of indefinite duration ; leaving us
no vestige of a beginning,— nor prospect of an end. Agreeable to
this hypothesis, the Doctor imagined that coal is formed by the
slow deposition of oily and bituminous matters at the bottom of
the sea. These bituminous and oily matters he supposes to have
originated in the dissolution of the various animal and vegetable
bodies, which are continually perishing on the surface of the earth,
and in the waters of the ocean. The fuliginous matter which is
separated during the combustion of various bodies on the surface
of the earth, he supposed to be washed off the surfaces on which
it fails, by the rain, and, being thus made to flow into the rivers^, is
carried by them into the sea ; where it also adds, by its deposition,
to the mass which is accumulating at its bottom. Another source
from which he supposes this matter to be derived, is the moss-water,
or the water which drains from peat-mosses. This moss-water, the
Doctor says, leaves upon evaporation, a bituminous substance,
which very much resembles fossil coal ; and, as the continued action
oif the sun and atmosphere upon this oily substance tends, by in-
spissation, to make it more and more dense or bituminous, he,
therefore, saw no difficulty in supposing a continual separation of
this bituminous matter, or inspissated oil, from the water; and a
precipitation of it to the bottom of the sea, along with the subtle
earthy particles which the water also contains. These he supposed
to subside together in an uniform manner, producing a stratified
mass, which, becoming covered by an immense weight of super-
incumbent earth, must have been thereby exceedingly compressed
and condensed, and finally consolidated, by the powerful influence
of subterranean heat.

Waving, as foreign to the immediate object of our inquiry, any

236

observations on Dr. Hutton's general geological system, I shall
only here remark, that his particular theory, respecting the forma-
tion of coal, is exposed to the same insuperable objection, as was
offered against the hypothesis just noticed, that of making sub-
stances of much less specific gravity than water, sink through that
fluid. Can any intermixture with impalpable earthy matters, which
the Doctor supposes to take place during their subsidence, pos-
sibly authorize the supposition that light bituminous, or fuliginous
matters, or vegetable or animal oils, could subside through the
waters of the ocean, so as to form this extraordinary subaqueous
stratum of fossil coal ?

The opinions of Dr. Hutton have been combated by several inge-
nious writers; but those which respect the origin of coal have been
attacked by no one more successfully than by Mr. Williams, in his
History of the Mineral Kingdom. This gentleman, possessing a
very considerable degree of knowledge on this subject, the result of
actual observation, and confining himself to those inferences which
seemed necessarily to flow from the phenomena which he remarked,
concluded that the antediluvian timber was the original of our pre-
sent coal. This conclusion he was kd to make, from ha v ing ob-
served the form, grain, and texture of timber so frequently in coal.
He observes, that wood is the origin of coal is so plain and evident
a truth, that we can almost trace and point out the particular species
of wood which composed particular species of coal*. He more
particularly delivers his opinion in another place, where he says,.
" I am of opinion that the antediluvian timber floated upon the
chaos, or waters of the deluge, until the strata of the highest moun-
tains were formed, with much of the other strata in our. sight; and
that during the height of the deluge, and the time in which the
greatest part of the strata were forming, the timber was preparings

%

* History of the Mineral Kingdom, vol. i. p. 251,

237

and fitted, for being deposited in strata of coal ; and that the coals,
with their concomitant strata, were among the last that were formed.
But how, and by what means, every thing in this great work was
fitted, and carried on, belongs to higher wisdom and intelligence
than mine to explain*/'

" I will beg leave," Mr. Williams saysf , " to propose another pro-
bable source of coal. I believe, I may call it a real one, and that
is the antediluvian peat-bog/' The grounds on which Mr. Williams
formed this opinion were, the having seen coals, which seemed to
bear a very strong resemblance to peat ; and, on the other hand,
peat, which, on being dried, became nearly as black, and as hard
as coal. The particular reasons Mr. Williams employs for this latter
opinion, I shall at present defer, since they will appear when I shall
presume to offer some conjectures on this subject. Petroleum, Mr.
Williams is, however, convinced, is not at all concerned in the for-
mation of coal; although he acknowledges that some species of
petroleum may have a near relation to coal.

It is right to apprise you, that not only has tfre conversion of
petroleum into coal been thus strenuously opposed, but that the
derivation of petroleum itself from vegetable matter is also denied.
The learned Wallerius strongly objects against such an origin;
grounding his objections chiefly on it differing so much in its sen-
sible, as well as chemical qualities, from vegetable matter. He is
the more confirmed in his opinion, from the petroleum being found
inclosed in mountains, and in subterranean cavities, where no traces
of decayed vegetables are to be seen. Considering also, that
there is no reason to suppose that nature is less disposed to form
an oil in the mineral kingdom, than in any of the others, he con-
cludes that naphtha is generated from a most subtile inflammable

* History of the Mineral Kingdom, vol. ii. p; 212. f Id. vol. ii. p. 1 94-.

mineral matter, combined with water by the medium of an acid.
Petroleum he supposed to be formed by the addition of a calca-
reous earth to the naphtha, dissolved and retained by its acid
part. From the further combination with earth he supposed that
maltha was produced ; and by the exsiccation of this, asphaltum.

Monsieur Tingry, in his observations on some extraneous fossils
of Switzerland *, considers the detritus of organized bodies^ buried
in the earth, to be the true matrix of the different liquid and
solid bitumens; believing that these organized bodies are made
to assume those characters which distinguish them, more or less,
from the substances from which they originated, by the influence
alone of mineral vapours -f. He supposes the different states of
hardness, tenacity, or fluidity, which characterize coals, maltha,
petroleum, &c. to be entirely the consequence of spontaneous de-
compositions, and ne^ combinations, effected by mineral vapours,
and particularly by a certain quantity of water -These substances
he supposes to thus undergo, during the revolution of ages, and in
the silence of nature, an analysis similar to that which takes place
in closed vessels : becoming heated in consequence of their slow
decompositions, and new combinations ; and thus being resolved
into coal, which frequently manifests the form, or at least the cha-
racteristic marks, of organized bodies $. This operation he sup-
poses is, beyond doubt, accelerated by the presence of certain mines
of iron ; since he observes that Derbyshire furnishes a mixture of
iron and manganese, which takes fire spontaneously on being
moistened with linseed oil. Subterranean fires, he therefore con-
jectures, may be produced by the mixture of oil of petroleum,
with a similar ore of iron with that just mentioned.

* Transactions of the Linnaean Society, vol. i. p. 57. t Id. p. 59. $ Id. p. 60.

239

It is reasonable to conjecture, he thinks, that the remains of
vegetables, accumulated in large heaps, and exposed to the effects
of those particular combinations which occasion the heat of certain
mineral waters, or to the influence of volcanic fires, may have un-
dergone a real distillation ; and that the substances thus formed,
meeting with water which impeded their further decomposition,
have been carried to the surface of the earth, and appear there
under the form of naphtha, &c. Under other circumstances, he
conceives, that these same oils, thus detached by distillation from
the wood, have filtered insensibly into the beds of sand and clay,
and thus have produced the formation of coal and bituminous
schisti ; whilst, under other circumstances, these oils, accumulated
in the interior cavities of the earth, have assumed the consistence
which we observe in mineral pitch.

To the opinion of Mons. Tingry, respecting the gradual decom-
position of vegetable matter, I certainly cannot object ; but later
observations, and particularly those of Mr. Hatchett, have clearly
demonstrated, that, however difficult it may be to account for the
different states in which the bitumens are found to exist, the action
of subterraneous fires, and the operation of distillation, cannot have
been the agents which have occasioned those varieties, in the forms
under which these substances appear to us. It may be proper to
remark, with respect to this supposed influence of subterranean
fires, that Dr. Hutton, and many of the French chemists, have
adopted the same idea, and to as considerable an extent.

Dr. Darwin was of opinion, that morasses seem to have under-
gone a, fermentation ; but that the formation of coal depends on a
distillation similar to that which is supposed by Dr. Hutton. The
Doctor says, that " woods in uncultivated countries have grown
and fallen through many ages, whence morasses of immense extent;"
or, as he expresses it,

240

Gnomes ! you hen taught intruding dews to pass
Through time-fall'n woods, and root in wove morass,
Age after age ; and with filtration fine
Dispart, from earths and sulphurs, the saline.

BOTANIC GARDEN, Canto II. 1. 115.

" In other circumstances/' the Doctor adds, " probably where less
moisture has prevailed, morasses seem to have undergone a fer-
mentation, as other vegetable matter ; new hay is liable to do so,
from the great quantity of sugar it contains. From the great heat
thus produced in the lower parts of immense beds of morass, the
phlogistic part, or oil, or asphaltum, becomes distilled, and rising
into higher strata becomes again condensed, forming coal-beds of
greater or less purity, according to their greater or less quantity of
inflammable matter; at the same time the clay beds become purer
or less so, as the phlogistic part is more or less completely exhaled
from them *"

Mr. Kirwan differs entirely from every one of these opinions ;
and derives the origin of coal from the disintegration, and decom-
position, of primaeval mountains, containing a large proportion of
carbonaceous and bituminous matters — But it is proper that this
novel and interesting suggestion should not be deprived of the
advantages it must derive, from being given in^ Mr. Kirwan's own
words.

" My opinion/' Mr. Kirwan says, " is, that coal-mines, or strata
of coal, as well as the mountains or hills in which they are found,
owe their origin to the disintegration, and decomposition, of pri-
maeval mountains, either now totally destroyed, or whose height and
bulk, in consequence of such disintegration, are now considerably
lessened. And that these rocks, anciently destroyed, contained,

. • * Additional Notes to Botanic Garden, note xvii.

241

most probably, a far, larger proportion of carbon and petrol, than
those of the same denomination now contain, since their disinte-
gration took place at so early a period/'

On this supposition, Mr. Kirwan proceeds to say, "I think the
formation of coal-mines, and most of the circumstances attending
them, may naturally be accounted for.

" And, first, as to the seams of coal themselves, and their at-
tendant strata; they must have resulted from the equable dif-
fusion of the disintegrated particles of the primitive mountains,
successively carried down by the gentle trickling of the numerous
rills that flowed from those mountains, and in many cases more
widely diffused by more copious streams. By this decomposition,
the felspar and horn blend were converted into clay ; the bitumi-
nous particles, thus set free, reunited, and were absorbed, partly
by the argil, but chiefly by the carbonaceous .matter with which
they have evidently the greatest affinity ; since they are separable
by boiling water from the former, and scarcely, by the strongest
heat in close vessels, from the latter ; and even in an open fire, only
by a heat much superior to that of boiling water. The carbonic
and bituminous particles, thus united, being difficultly miscible
with water, and specifically heavier, sunk through the moist, pulpy,
incoherent, argillaceous masses, and formed the lowest stratum,
unless in cases where their proportion to the argillaceous particles
was so small, that the latter had subsided and coalesced, before
the former could have been reunited ; in that case the clayey par-
ticles formed the lower stratum of indurated clay. But if the
petrol were in the greatest proportion, it frequently sunk first, in
the form of a soft bitumen, carrying with it the clay, and forming
beds of shale, or bituminous shale, according to its proportion.
By oxygenation it becomes specifically heavier than water *."

* Geological Essays, p. 330.
VOL. I. II

242

To attempt to overthrow opinions erected on so broad a basis, as
the vast portion of- chemical and mineralogical knowledge which
Mr. Kirwan possesses, cannot but, at first sight, appear to be an act
too presumptive to promise the least success. But when even the
most wise and intelligent loosen the reins, and lessen those restraints
which their judgment, in general, places on their imagination, he
who first notices any unwarrantable deviation from established
principles may, without fearing censure for his interference, boldly
venture to point it out.

The disposition of the various substances, of which the earth is
composed, yields us so little satisfactory information; and the data
we thus obtain are so few, and so unconnected, as to render the aid
of conjecture indispensably necessary. Hence, on the subject of
the formation of this globe, and of the various revolutions it has
suffered, the wisest men have formed the most extraordinary and
romantic conclusions. Nor can this occasion surprise, when it
is considered, that to point out the operations of nature, by which
the various substances which constitute the earth obtained their
present figure and arrangement, is, in fact, an attempt to form a
history of the most remote periods, with the scantiest stock of ma-
terials possible. In such a performance, success cannot frequently
be expected ; it must resemble the bold sketch of a master, who.
whilst depicting scenes which have originated in his own rich fancy,
strives, but, perhaps, ineffectually, so to correct them by his judg-
ment, as to make them accord exactly with nature. To approach
near to the completion of such an undertaking requires a consi-
derable portion of genius, the efforts of which must be directed by
a mature and correct judgment ; whilst very inferior abilities indeed
may be sufficient, to enable any one to point out an instance or two
of disagreement, between the conjectures which are offered, and the
circumstances they are intended to explain. This 1 shall therefore
attempt.

243

In the hypothesis of Mr. Kirwan, the most obvious difficulty
seems to be in admitting the prompt subsidence of the finely
divided particles of so light a substance as bitumen, through the
waters of the ocean. Mr. Kirwan supposes tlie carbonaceous, as
well as the bituminous particles, to be separated by the disinte-
gration of the antediluvian mountains ; and then to enter into
reunion, and suffer a precipitation through the water. Such a
combination I have endeavoured to prove is constantly taking
place, in every case where the thickening of the substance and the
darkening of the colour, of any bituminous substance is going
on. Thus, in consequence of the addition of oxygen to the thin
and limpid naphtha, a combination of that principle with the
carbon ensues ; and the fluid becomes thicker and darker, assum-
ing the form of petroleum. By a continuance of this process,
these effects are produced in a still higher degree, and the hard,
dark bitumen, asphaltum, or the still more highly carbonaceous
bitumen jet, is formed. But every one of these substances, we
perceive, are of such a degree of specific gravity, when pure, as
not to allow us to assume the possibility of their sinking through
the moist, pulpy, argillaceous mass, as Mr. Kirwan describes it;
neither could it possibly be admitted, even if such a subsidence
were granted, that such materials should form, as Mr. Kirwan also
conjectures, the lowest stratum.

Whilst on this subject, I must make one more observation, which
appears to me very forcibly to contradict this supposition of the
formation of coal by deposition. The specific gravity of the sub-
stances forming the roof of coal, constantly exceeds in a very high
degree that of the bituminous mass they cover; they containing
very frequently so much metallic matter as to render them exceed-
ingly ponderous. Now the disintegration, of which Mr. Kirwan
speaks, he supposes to have been so complete, as to have converted

244

the hard and close-grained hornblepd and felspar into clay. By so
minute a disintegration, the bituminous particles must have been
set free ; and must have risen to the surface, with as great a degree
of rapidity, as the earthy and metallic particles would have sought
the bottom. But, on the supposition of Mr. Kirwan, the bitumi-
nous and carbonaceous, the earthy and the metallic particles, be-
ing all suspended in the same fluid, a deposition of the carbon and
bitumen must have first taken place, and this have been succeeded
by the descent of the earthy, and of the still more ponderous
metallic particles.

It appears equally difficult to conceive the formation of beds of
shale, by the subsidence of bitumen. If; says Mr. Kirwan, the
petrol were in the greatest proportion, it frequently sunk first, in the
form of a soft bitumen, carrying with it the clay,, and forming beds
of shale, or bituminous shale, according to its proportion. Consi-
dering this position, with all that care and deference, which a dis-
sent from the opinions of so justly celebrated a chemist ought to
excite, I still arn unable to discover, how the effects, here described,
could possibly result from such a combination of circumstances,
as those to which they are thus ascribed.

Mr. Hatchett, whose most valuable observations on the bitumens
have very much facilitated our inquiries, into the nature and origin
of these substances, is very decidedly of opinion that coal, as well
as the other bitumens, are of vegetable origin ; although he does
not deny the possible intermixture of animal matters. But we shall
soon have occasion to advert more fully to these observations, to
which the science of chemistry is so much indebted.

Mons. Patrin states, that volcanoes throw up large quantities of
bituminous and argillaceous matters; and he derives the origin of
coal from this source : supposing that coal, and its interposed beds
of stone, have been deposited by the alternate ejection of bitumen,

245

and of earthy matters, from submarine volcanoes. How, he says,
can it be supposed, that coal can have been formed from vege-
tables, when considerable beds exist at the height of twelve thou-
sand feet in the Cordilieres of Peru, and at more than six thousand
feet in height on the Dauphinese Alps ; where, he adds, these beds
have been deposited, at a time when vegetables did not yet exist,
and when the waters covered the whole surface of the globe. How
otherwise, he asks, can we account for the regular alternate beds
of coal and layers of stone ; such as, for example, are seen in the
colliery at Liege, where there are sixty-one beds of coal, alternating
with as many layers of stone, of a vast thickness*.

The latest writer of celebrity on this subject is Mons. Fourcroy,
who, speaking of the origin of this substance, says, the greater part
of naturalists consider coal as the product of the remains of wood,
which has been sunk, and afterwards changed by the water, and by
the salts of the sea. Coal, he observes, seems to owe its formation
to the decomposition of an immense quantity of marine and terres-
trial vegetables, and to the separation of their oil, which becomes
united to the aluminous and calcareous earth. It cannot be denied,
he remarks, that animal matters also enter into its composition,
and afterwards observes that a considerable quantity of ammonia
is yielded by the distillation of coal, which favours the opinion of
its animal origin, since bodies belonging to this class of compound
substances always yield ammonia during their distillation-)-.

Evident indecision is observable in the foregoing opinion, re-
specting the formation of coal ; doubtlessly arising from Mons.
Fourcroy 's disposition to countenance the idea of animal bodies
having contributed greatly, and perhaps even more than vegetables,

* See article HOUILLR, Dictionnaire d'Histoiric Naturelle.

t Systenie des Connoissances Chymiques, torn. viii. p. 241 et 244.

246

to the formation of some kinds of bitumen. Want of that pre-
cision, which, in general, marks the observations of this celebrated
chemist, is also discoverable in the explanation he offers of this pro-
cess of nature.

The supposition of the separation of oil from the mass of decom-
posing vegetables is not sufficiently supported by the facts which
manifest themselves, during the resolution of vegetable matters, to
allow it to form the basis of a system, intended to explain this
extensive and mysterious operation. For if such a separation of
the vegetable oils were even admitted, could the quantity of a
principle which vegetables, in general, possess so sparingly, be con-
sidered as sufficient to account for the immense masses in which
this substance is known to exist ?

Yours, &c.

LETTER XXIV.

INQUIRY RESPECTING THE ORIGIN OF COAL CONTINUED.. ..HY-
POTHESIS PROPOSED....MOSAIC ACCOUNT OF THE DELUGE....
OBJECTIONS AGAINST. ...UNIVERSALITY OF THE DELUGE....
CHANGES THUS EFFECTED. ...VEGETABLE MATTER DISPOSED IN
SITUATIONS IN WHICH COAL NOW EXISTS.

1 HAVE been highly entertained by a letter from our friend Winton,
in consequence of your having shown him my account of the va-
rious systems respecting the formation of coal. Indeed his remarks

24?.

are so just, and his satire so pointed, as to give me some appre-
hension for the fate of my present letter, when subjected to his
criticism and keen raillery. He reminds me of Dr. Halley's con-
jecture, that the world on which we dwell may have another habit-
able world within it, to which may be attached a system of sub-
terranean luminaries, resembling those which yield light to our
upper world, but necessarily moving within a smaller sphere*. He
sarcastically asks, whether our volcanoes are any thing but the
grand outlets of the furnaces, and our veins of bitumen any thing
more than the clogged-up chimnies of this inner world ? The dread
of criticism must not, however, deter me — I have engaged myself
to the work, and therefore must not shrink.

Having laid before you the several opinions which have been
published, respecting the formation of coal, and having found my-
self under the necessity of stating my suspicion of their insuffi-
ciency, to account satisfactorily for the origin of this substance, it
becomes a duty to offer any observations, which may seem to be
likely, in the least, to elucidate a subject involved in so much mys-
tery. But be assured that, whilst doing this, I am not ignorant of
the difficulties which surround me ; nor, knowing how considerable
these are, do I presumptuously expect to establish an impregnable
system. On the contrary, I fear, that many unforeseen, and power-
ful objections may arise, against opinions thus hazarded, on a
question which has been left in a great measure undecided, after
careful discussion, by men of eminent abilities. If, on the one
hand, I experience the mortification of differing from opinions
which have been generally received ; it is, on the other hand, highly
satisfactory to know, that this difference is so little, as, in some in-
stances, to consist merely in an extension, and in others, in little
more than a modification, of those opinions. Thus the explana-

* Miscellanea Curiosa, p. 43.

248

tion here offered will be found in perfect coincidence with that
given by Mr. Hatchett, Mr. Williams, and Mons. Tingry, as far as
regards the derivation of coal from vegetable matter ; differing only
from that of the two former gentlemen, in its attempt to ascertain
the nature of the process by which the, change has been effected ;
and from that of the latter gentleman, in not acknowledging the
necessity of the general operation of mineral vapours or subterra-
nean fires and distillation.

The opinion, which the strictest examination of every circum-
stance seems best to warrant the adoption of, appears to be, that
coal is a product of the vegetable matter, which has been buried
at several distant periods, but chiefly in consequence of an uni-
versal deluge ; and which, after having been reduced to a fluid state
by the bituminous fermentation, has suffered a certain modification
of that inflammability, which bitumens in general possess, by the
deposition of its carbon, and by an intimate and peculiar intermix-
ture with various earthy and metallic salts.

In examining the solidity of this hypothesis, the attention must
become particularly engaged by three different circumstances,
which offer themselves as necessary objects of inquiry. In the first
place, the necessity presents itself, of ascertaining, whether the de-
luge may have been capable of occasioning that deposition of the
matter of which coal is formed. In the next place, it should be
determined, whether the circumstances under which this matter has
been deposited, were likely to occasion it to undergo such chemical
changes as would produce its transmutation into coal. Lastly, it
is requisite to discover, how far this suppositious change accords
with the general ceconomy of nature ; or, at least, with that part of
it which it has been permitted to us to understand.

The general tenour of the Mosaic account of the creation of the
world, as well as several distinct expressions employed by the
sacred historian, whilst speaking more particularly of the creation

249

of the vegetable system, yield the strongest grounds of belief, that
the earth, in its antediluvian state, was most plentifully stocked
with plants and trees of every kind and size. The employment
which was allotted to Adam, for " the Lord God took the man,
and put him into the garden of Eden to dress it and to keep it*,"
and the extensive space which this garden is implied to have filled,
for " out of the ground (of this garden) made the Lord God to
grow every tree that is pleasant to the sight, and good for food," as
well as the general scenery, and the most prominent circumstances
in this history of the first man, all concur to shew, that the man-
date of the Creator was, in this respect, completely fulfilled, and
that " the earth brought forth grass and herb, yielding seed after
its kind, and the tree yielding fruit, whose seed was in itself, after
his kind-)-."

Agreeable to the same sacred tradition, the earth was peopled
from a single pair ; and, from various particulars which appear in
the history of their immediate descendants, we may perceive, that
the arts which they possessed, and the kind of life which they led,
accorded with those which the historians of later times have shewn
to have been adopted by the aboriginal inhabitants of every country.
Their dress was simple ; and their employments, that of keeping of
cattle, and of tilling the ground, were those of man in his rudest
and most uncivilized state.

After a certain period, seven generations from Adam, we are told
the arts of civil life began to appear. " Jabal was the father of
such as dwell in tents, and of such as have cattle — Jubal was the
father of such as handle the harp and organ — and Tubal Cain was
the instructor of every artificer in brass and iron:):." Whether
this relation is to be taken literally, and that these arts were actu-
ally invented during the eighth generation of mankind, or whether

* Genesis ii. 15. t Genesis i. 12. J Genesis v.

VOL. I. K K

250

this account was only meant to designate the regular progress of
the first race of men from a rude to a civilized state, will not affect
the present object of inquiry. A period sufficiently long to allow
a prodigious increase of the vegetation which adorned the surface
of the earth, must have elapsed, whilst the first families of man-
kind were thus emerging from a state of rudeness to that of civili-
zation. For during that period in which a people exist only in a
state of nature, as it is termed, the wants which they feel, and
consequently the arts which they cultivate, being few, necessity
will but seldom oblige them to level the trees of their surrounding
forests. Thus uninterrupted, the earth, which has been assumed to
have been well clothed, even immediately after its formation, must,
in the succeeding early ages, have teemed, in almost every part of
its surface, with vegetable life.

From the same records we learn, that, after the earth had existed
during the period of sixteen hundred years, the Almighty decreed
that a flood of waters should be brought upon the earth, and that
the earth should be thus destroyed. All the fountains of the great
deep, we learn, were broken up, and the windows of heaven were
opened. Forty days and forty nights it rained . upon the earth, all
the high lulls that were under the whole heaven were covered, and
the waters prevailed upon the earth* an hundred and fifty days *.

Various objections have been offered against this, the Mosaic,
account of the deluge. Men of the greatest learning and piety
have doubted, whether the relation should be taken literally or
not; and have differed very much, in their opinions, as to the ex-
tent to which this astonishing revolution of the earth reached.
Some have doubted the existence of a sufficient quantity of water,
to deluge the highest mountains of the earth ; whilst others, among
whom may be mentioned the Right Rev. Bishop of Clogher, have

* Gen. vii.

251

imagined, that the deluge should not be considered as having
covered the whole face of the earth. His Lordship was of opinion,
that some parts of the then habitable world, which by the force of
the deluge were separated into islands, and were divided from the
continent whereon the ark landed, were in some sort exempted
from the common calamity, brought on the rest of the world by
the deluge ; inasmuch, his Lordship says, as the continent of Ame-
rica, and many islands in the East Indies, are at present partly
inhabited by wild beasts and noxious animals, which it is not rea-
sonable to imagine, that any body could or would, have imported
thither since that time *.

To account for this particular circumstance, may not, perhaps,
be very easy; but, however, it is not necessary to be done, in
proving the prevalence of the deluge over every part of the known
world ; since testimonies sufficient to this fact, are yielded by those
wonderfully preserved remains of former ages, which form the ge-
neral subject of these inquiries, and which have been discovered in
almost every part of the known world. Even the very spots which
were thus pointed out, by his Lordship, as having been exempted
from the fate of the rest of the world, contain the most astonishing
and interesting remains of organized beings ; at once proving that
the waters of the deluge did cover the whole earth, and leading us
to regard the globe we inhabit as one vast tomb of a former world.

Assuming it then as proved that the deluge did overwhelm the
whole of this globe, it next becomes necessary, to inquire what
changes were probably thus effected. Very different opinions have
been maintained respecting the degree of change which took place
on the earth, in consequence of the deluge. Some have supposed
that the change was but slight and superficial, affecting the upper
surface only of the earth ; but others, considering the declaration

* Vindication of the Histories of the Old and New Testament, p. HI.

252

of the Almighty's intention to destroy the earth, as well as its in-
habitants, " God said — Behold, I WILL DESTROY THEM WITH THE
EARTH *," conclude that all the strata of the antediluvian earth
were actually dissolved, and their constituent corpuscles separated
one from another; and that, in this state of separation, they were
mixed with a large quantity of water, so that the whole was reduced
to a fluid colluvies f. The attempt to determine what changes
were actually effected at this period, cannot be expected to prove
very successful ; but perhaps a near approach to truth would be,
the supposition that the force of this immense quantity of fluid mat-
ter must have been such, as to have destroyed the whole of the ori-
ginal surface, and to have considerably deepened and widened those
excavations which had contained the antediluvian waters ; whilst,
by the falling of vast subverted masses, other cavities would be
filled, and former channels choked up. By the violent agitations
which the waters must for a considerable time have endured, the
earthy matters they contained must have suffered the highest de-
gree of attenuation, and division; and, by their gradual deposition
in those situations in which the waters were less agitated, or where
they became stagnant, must have formed horizontal strata, where
the surface on which they were deposited was flat; and new moun-
tains, where this deposition was made on the elevated subaqueous
remains of former mountains.

Possessing no other data from which we can infer what form the
surface of the antediluvian world bore, we can only rest on the
mention of its rivers, and its high hills, which give us reason to
suppose it might have borne some affinity with that which the pre-
sent surface of the earth presents to our view ; and the sides of the
hills, with their correspondent valleys, and the extended plains, it
may be concluded, were covered with their appropriate tribes of

* Gen. vi. 13. t A Treatise on the Deluge, by A. Galcott, 1761.

\

253

trees and plants. Assuming these for the generalities of the earth's
external form, it is evident that the waters, whether supplied by
the rain alone, or by other sources, as seems to be implied by the
breaking up of the fountains of the great deep, must necessarily
have first filled the lower parts of the earth. When it attained a
greater height, then must this powerful element have rushed in
torrents from valley to valley, breaking down, or surmounting,
every intervening obstacle ; and laying prostrate the vast forests
with which the surface was every where clothed. Of the trees thus
overthrown, the lowest stratum of vegetable matter would be
formed, which would soon become buried beneath the sediment,
which would be continually depositing from the superincumbent
waters, loaded with every species of earthy, and even mineral mat-
ters, with which they would be impregnated by the effects of an
alluviation more powerful than we can possibly conceive.

As the volume of the water increased, the sides of the mountains
would become subjected to the violence of its action. The roots of
the trees, which grew on their sides, would become loosened, and
the trees themselves, and the earth in which they had grown, with
the various other vegetables which had been generated and nou-
rished in the same matrix, would fall into the flood, and become
collected in particular spots. Thus would masses of vegetable
matter, immense beyond conception, become subjected to the domi-
nation of this powerful element. These several masses of vegetable
matter would become covered by strata of earth formed by the gra-
dual deposition of ponderous, but minutely divided particles, which
would soon form a covering so compact, as would be able consi-
derably to resist the ordinary fluctuation of the water. Similar
alternating strata, constituted^ by the accumulating masses of vege-
table matter, and the subsidence of particles of earth, may be sup-
posed to be thus continually forming until the waters had covered
the tops of the high hills.

254

From what cause it proceeded, it will perhaps, be impossible
ever to determine ; but there is certainly reason to believe, that the
waters of the deluge possessed a very considerable solvent power
over even those earths which we consider as most untractable. From
the intermixture and crystallization of these proceeded those silici-
ous and spathous veins which alternate with and intersect the various
strata, which form that part of the earth which has been subjected
to our examination.

Not only the form, but the substance, of the surface of the
newly-formed postdiluvian world must have differed very much
from that which existed before the flood; vast and innumerable
must have been the changes, which it must have undergone, before
the respective situations of the waters, and of the dry land, could
have even made an approach to stability. From the violent action
of the waters at the period of their first effusion over the earth,
as well as during their residence and their departure, the conti-
nuity of the earth must have been broken in many places ; necks of
land must have been left, forming, according to circumstances,
isthmuses, or promontories ; vast masses of earth, considerably un-
dermined, would remain on the superior parts, and on the declivi-
ties of mountains ; and, as vegetation would doubtlessly be rapidly
renewed, wherever the earth became uncovered from the waters,
these projecting parts would soon be covered by the verdure of
various vegetables. But the newly-formed surface would, perhaps,
for a considerable period, be continually undergoing a change of
its form ; the waters, urged by violent tempests, and agitated by
receiving the immense fragments of falling mountains, might sepa-
rate those necks of land of which we have just spoken, and which
its slower action had been continually reducing ; the divulsed parts
of which, with the vegetation they bore, would sink in the waters
of the ocean. Thus also, by the force of tempestuous winds, and
even by the gradual influence of the weather, large projecting and

255

dependent portions of mountains, with their newly-produced forests,
would frequently be sinking in the surrounding waters. Thus would
additional layers of vegetable, and of earthy matters, be repeatedly
formed over those strata of vegetables which had been overthrown
by the first violence of the deluge.

As when the greater part of the waters of the deluge had drained
off, and when the surface of the globe again became divided into
water and dry land, the lower and more excavated parts would
necessarily retain the water for a long time ; thus, as well as the
rivers and seas, would immense lakes be formed. In these lakes
would the numerous tribe of aquatic plants flourish, which, as the
waters at last subsided, would cover the bottoms of these hollows
with a mass of vegetable matter, which becoming gradually covered
by a coat of earth, would be secured from the action of the air.
From the numerous revolutions which the newly-formed earth would
be destined for a time to undergo, many of these hollows might be
again filled with water. Adjoining lakes might burst through their
interposed mounds, and thus refill them ; or among the mountains
which helped to form the basons of these lakes, some of which had
been weakened in their bases, by the previous action of the waters,
might now become more effectually undermined, and might fall
into the lake beneath, and thus force the water beyond its newly-
established limits. In new lakes thus formed in the cavities of
previously existing ones, aquatic vegetation would again go on,
whilst a compact stratum from the subsidence of the suspended
earth would form at the bottom ; and when the waters themselves
had drained away, a fresh accumulation of vegetable matter would
be formed, which would, like the former, become covered with a
stratum of mud, capable of acquiring, as in the former instance, a
considerable degree of hardness.

Such of the vegetable matters, as might float on the last re-
maining waters of the deluge, might be washed into other hollows

256

of less depth, and, becoming only covered with a moderately thick
coat, would become peat bogs ; and, if left for a long series
of time totally undisturbed, would, perhaps, form lakes of petro-
leum, similar to that which now exists in the island of Trinidad, a
description of which has been already given in the Fourteenth
Letter.

When we reflect on the situation of coal, and of the various
strata which are interposed between its several beds ; it must, how-
ever, be admitted that considerable difficulties still oppose the satis-
factory explanation of these phenomena. Among these, not the
least is the frequent alternation of coal and lime-stone, and which
undoubtedly best agrees with the idea of immense lakes of sea or
fresh water undergoing alternate fillings and emptyings : in the
former state, depositing strata of stone, and in the latter, forming
beds of decomposing vegetable matter.

Yours, &c.

LETTER XXV.

INQUIRY WHETHER THE VEGETABLE MATTER WAS DEPOSITED
AT THE DELUGE UNDER CIRCUMSTANCES FAVOURABLE TO ITS
CONVERSION TO COAL.. ..BITUMEN ALONE NOT FITTED FOR
FUEL. ...OTHER MATTERS NECESSARY TO BE ADDED. ...PECULIAR
ARRANGEMENT OF THE PARTICLES.

THE next question which demands consideration is, whether such
an arrangement of the materials of the flooded surface of the ante-
diluvian world, as has been assumed in my last Letter, would be

257

likely to promote such chemical changes, in the strata of vegetable
matter, as would effect its conversion into coal ? This we will there-
fore now inquire into.

That vegetable substances placed in a mass, in a subterranean
situation, will, with the aid of moisture, and perhaps, with only that
which they themselves contain, pass into a peculiar fermentation,
and become thereby converted into bitumen, has been already
asserted. Your attention must here, however, be requested to one
additional consideration ; which will serve, very probably, to sup-
port the application of that hypothesis to the present subject, the
origin of coal.

In the promulgation of that hypothesis you perceived, that the
circumstance, on which the bituminizating process was supposed
essentially to depend, was the seclusion of the vegetable matter
from the atmospheric air. According to the accuracy with which
this part of the process was performed, it necessarily follows, would
be the approach to a state of perfection, in the product of the ope-
ration. Now, by a slight revision of what has been said, in the
Letter immediately preceding this, you will not fail to perceive,
that whilst endeavouring to ascertain the most probable mode, in
which the vegetable matter of the antediluvian world was disposed,
there appears great reason to suppose, that the disposition of it
must have been such, as would most certainly secure the comple-
tion of the assumed process.

Buried in a considerable mass, — thoroughly imbued with water*
and covered over with dense, compact strata of earth, its seclusion
from the atmospheric air must have been very accurate ; and tak-
ing it for granted, that the change it was to undergo would de-
pend on these circumstances, then we have every right to conclude,
that its conversion into bitumen would be produced most certainly
and effectually.

VOL. I. L L

258

From what has been already said, whilst speaking of the forma-
tion of bitumen, you will have perceived that, I am of opinion
that, in proportion as the process of bituminization approaches to
perfection, the substance acted upon acquires a state of fluidity.
With respect to coal, the formation of which may be regarded as
the grand and important end, for which this process has been insti-
tuted, it would be reasonable, d priori, to conclude, that the laws
of nature would decree, that the substance which is to undergo this
necessary change, should, in general, be so disposed, as to have
secured to it the full effect of the operation in every stage of the
process. But should the circumstance of coal having existed in a
state of fluidity, be supposed to be not fairly inferable from these
premises, some increase of the probability of the circumstance
may surely be derived from a view of the substance itself. For
whether we dwell upon the peculiar fracture of common coal, or
on the vegetable impressions which are frequently found on it, the
idea of its having existed in a fluid state must present itself to any
one, whose mind has not been prepossessed by some contradictory
hypothesis.

From this state of fluidity would result a very important change
in the nature of the mass. With the vegetable matters which have
been supposed to have been accumulated by the waters of the de-
Juge, a considerable portion of mud and gross earthy particles must
have been blended ; these, however, when bituminization gave
fluidity to the mass, would, in consequence of their superior gravity,
settle, and form that stratum which was to become the floor of the
pit, leaving the pure bitumen above.

By reverting to a circumstance mentioned whilst speaking of
peat, and of bituminous wood — their eager retention of the water
in which they had been immersed, parting with it as difficultly as
would a sponge ; and that only on the employment of a considerable

259

degree of pressure — we learn, that water may be so thoroughly in-
terspersed between, and so intimately united with, the particles of
bitumen, as to constitute a part of its mass. -This, htiwever, takes
place in the soft bitumens only, and when these substances have once
been deprived of the water they contain by exsiccation, they are no
longer capable of entering into union with it ; becoming imperme-
able to that fluid, with which every part had before been penetrated.
Thus, in many other substances, such as the balsams, gum resins, and
vegetable gluten, a certain portion of water enters into their original
composition, being a necessary constituent of the substance, whilst
existing in that form ; but when these substances become dry and
hard, water is capable of being united with them but very sparingly,
if at all. The Abbe Fortis, whilst describing the mine of pisasphal-
tum, in the isle of Bua, relates that, upon breaking the drops of
bitumen, which having exuded in a soft state, had become hard and
brittle, he found in the centre of each a drop of clear water. That
water exists formally in petroleum is rendered probable, by its
being produced in a considerable quantity by the distillation of
this substance. It must indeed be allowed, that, in the operation
of distillation, such a new combination of the principles of which
the petroleum is composed may take place, as may occasion the
formation of water ; the hydrogen and oxygen thus uniting, whilst
the carbon is left in the residuum contained in the retort : but that
water may exist in and form a part of the original substance, there
does not appear to be the least reason to doubt*.

* That water may exist in an intermediate state, between that resulting from the
actual combination of the principles which constitute water and their state of complete
separation, does not appear to be improbable. In siliceous and other hard bodies, ca-
pable of being reduced to a pulverulent form, and in no other way manifesting the least
trace of it, its presence is detected by distillation. From the observations of my inge-
nious neighbour, Mr. Hornblower, it appears, that the current of air from an hydraulic
bellowsp reduced a considerably greater effect, in augmenting the intensity and brilliancy

260

A circumstance which respects the roof of coal-pits is well deserving
your attention, in this place. Generally the schistose covering, which
forms the roof, is, for a considerable thickness, so impregnated:
with bituminous matter as to possess a degree of combustibility,
which is, in some intances, so great as to allow the employment
of these schisti, for the purpose of combustion, in the burning of
lime, smelting of metals, £c. A similar impregnation of the earth
which covers the fossil wood of Munden, and of that of Bovey, is
also observable. Impregnation of the earth to a considerable thick-
ness is also well known to exist in the earth in the neighbourhood
of petroleum springs. Thus, as has been already noticed, in the
valley of Noto, in Sicily, is a spring of petroleum, which discharge*
itself into the lake Palius ; and the earth above it, even to the sur-
face, is so much bituminized, as to have taken fire by accident and
to have burned for several months. The connection between these
several impregnations appears to be evident. As the resolution of
vegetable matter into a bituminous fluid takes place, so in propor-
tion will the adjoining earth become impregnated ; and where this
change is so complete that a fluid bitumen is formed, the diffusion
and absorption will, of course, be extensive, in proportion to its
fluidity. The bituminous schist, which is adjoining to beds of
coals, is evidently formed of such earths, as have become impreg-

of the fire to which its blast was applied, than a similar quantity of air, uro-ed with
an equal degree of velocity by a bellows of common construction., Might not the
agitation and intermixture of the air and water produce a partial separation of the prin-
ciples of the latter, into an intermediate gaseous state ; in which the two principles, be-
ing less closely united, would act on their application to the burning embers, with ener-
gies somewhat similar to those which the two principles exert when entirely separate.
Whether it exists in this partially decomposed, but permanent gaseous state, or entirely
decomposed into the two original permanent gases belonging to its constitution, as has
been supposed to be the state in- which it exists in the atmosphere ', must be left to,
future experiment to determine.

1 Nichoteop'a Journal, April 1801.

261

nated by the fluid bitumen, whilst the coal existed in the fluid state
of petroleum.

A revision of the several circumstances mentioned whilst describ-
ing the situation of coal, and its accompanying strata, will serve
not only to confirm the supposed origin of coal, but also to prove
the fact of its having at one time existed in a fluid state. The dif-
ferent partings, as they are termed, between the top of the coal
and the roof, deserve particular notice, on this account. In good
partings there sometimes exists a space between the coal and roof,
the coal being sprinkled with a powder like charcoal. In this case
the previous fluid state may be surely inferred without the least
difficulty, the space appearing to be the consequence of the drying
and contraction of the matter forming the coal, and after the superior
stratum, the roof, had acquired a considerable degree of firmness.
This inference must be made, almost without hesitation, in other
instances, where the parting is perfectly clear ; the head of the
mass of coal being described, by writers on this substance, as pos-
sessing a surface so smooth and polished, as if it had been varnished,
or covered by some fluid matter.

In confirmation of coal having existed in a state of fluid bitu-
men (petroleum), I must remark that this substance is frequently
found in the neighbourhood of coal. Thus Mons. Morand, who
thought that bitumen was probably the basis of coal, informs us,
that in the mines of Tranche Compte, the bitumen exudes in the
form of a sort of guhr (tears of the mines).

That the wreck of the vegetable part of the antediluvian world
was placed in such a situation as to be continually permeated by
water, and subjected to the conversion into bitumen ; and that the
nascent bitumen would unite with, and afterwards retain a portion
of this water, I have not, indeed, been able to present you with
actual proof; but have been only able to offer you evidence of a

262

circumstantial nature: which I, however, trust is of some consider-
able weight.

Bitumen alone would not, however, accomplish that grand pur-
pose for which nature formed coal ; that of supplying future ages
with a substance for fuel, which, by a moderate exercise of the
ingenuity of man, might be made to burn with almost every degree
of intensity ; from that which is employed to convey to the human
body a grateful sensation, to that which is necessary to fuse some
of the untractable metals.

The rapidity with which pure bitumen burns, would not only
occasion a considerable waste of it, if it were attempted to be
employed for the purposes to which coal is applied : but would
also render it so unmanageable, as entirely to prevent its useful
application, to even the most ordinary purposes, which coal is in-
tended to fulfil.

To moderate this high degree of combustibility, and so to regu-
late it, that the consumption of a substance, so necessary to man,
should be rendered uniform and economical, was therefore required.
To accomplish this, the intermixture of some incombustible sub-
stance with the bitumen became necessary. But to produce those
characteristic properties, by which coal is distinguished from all
other substances of the same class, a particular kind of arrange-
ment of the particles of this heterogeneous mass was requisite. It
was necessary that the bituminous particles should be so involved,
and insulated, on every side, as to be nearly defended from the
action of the fire. It was also necessary that the regularity of its
combustion should not be disturbed, by the superadded incombus-
tible matter existing in the mixture, in such gross particles, or in
so irregular a state of diffusion, as would have been the case, if the
earth had remained in it, in the state in which it had subsided
along with the sunken vegetable mass.

263

The arrangement of the respective particles of the mass, which
would make the nearest approach to the attainment of the required
object, would be that in which each individual particle of bitumen
would have its combustibility left unimpaired ; except so far as its
inflammability would have been corrected by the excess of its car-
bonaceous part : at the same time that, by the appropriate interpo-
sition of some nearly incombustible matter, such a check should be
given to the spread of the ignition, of one series of the bituminous
particles to another, as should render their combustion sufficiently
slow and gradual. Such an arrangement as might thus, cL priori,
have been supposed to be best calculated to produce this effect,
may be perceived, to have been actually employed, in the formation
of coal.

If a piece of common coal be washed in water, so as to remove
from its surface all the minute shattered fragments, which adhere
to it, the fingers will be found to be no longer stained by it ; and
with a lens of very moderate power, or even with the naked eye,
it may be plainly seen, that the bituminous matter is disposed in
an irregularly laminated structure, and that the horizontal surface
of each small and thin stratum is finely coated with an extremely
thin film. This film, or pellicle, may also be seen frequently to dip,
and pass through the substance of the bitumen ; intersecting the
horizontal septa nearly at right angles, and thus placing the bitumen
in distinct divisions, the parietes of which are formed of an incom-
bustible pellicle. This film, in general, reflects tints of a greyish
white, but sometimes it appears with the hue of bronze. Fre-
quently it is of a pyritous nature, shining with a bright metallic
lustre, or, as in the peacock coal, manifesting a beautiful iridiscent
appearance : frequently also, when the pellicle itself is of a greyish
white, it will be variegated with bright yellow pyritous illinitions ;
and sometimes spathous, or pyritous laminae, will be interposed, a
quarter of an inch, or even more, in thickness. On inspecting the

264

edges of the coal, each separate lamina will he found to be com-
posed of bituminous concretions, exhibiting the conchoidal frac-
ture, and shining with a considerable degree of lustre.

On letting a piece of coal fall on any hard body, thus breaking
it in such a manner as will not direct its fracture, but will allow it
to take place in such directions as accord with the natural divisions
formed by the interposed films, the fragments will in general be
found to assume the form of rhomboids or of parallelipipeds ; the
very forms which a body, whose parts were thus separated and dis-
posed, might be expected to exhibit, on being fractured.

The separating pellicles or interposed septa, in those specimens
which I have examined, appear to be formed of sulphate of lime,
containing a small proportion of alumine, and sometimes also of
sulphuret of iron. The presence of these substances in coal, is
manifested by the analysis which has been made of this substance.
Mons. Fourcroy has ascertained that the ashes of coal contain the
sulphates of iron, of magnesia, of lime, and of alumine; and, even
irj asphaltum, both the sulphuric and muriatic acids were found,
by Du Ble, in union with calcareous earth *.

By such an arrangement of the bituminous particles, and by the
frequent interposition of pellicles of incombustible matter^ which
have been just described, not only is the combustion of coal mode-
rated, but it is likewise so regulated that, in its employment for
common domestic purposes, the internal parts of even small por-
tions of coal are so protected, from the too rapid access of the

* How strongly the water, which was diffused through the bituminous mass, was im-
pregnated with these several particles, may be inferred from the frequent presence of
calcareous spar in the interstices and cavities of coal. Thus, in a specimen of coal now
before me, about nine inches in length, and about three inches in width, the substance
of the coal is beautifully intersected by numerous white streaks of spathose matter ; and
a large interstice, the whole length of the specimen, is covered with very white and per-
iect crystals of the dog-tooth spar, forming a beautiful contrast with the including coal.

265

oxygen, that only the external part is actually consumed and re-
duced to an ash ; whilst the other part is rendered a coke or cinder,
and is capable of being again employed ; and even, with increased
advantage, in many culinary and chemical operations. Here then
are we presented with one of the many instances, in nature's works,
of the obtaining of the most important ends, by a contrivance not
less remarkable for its simplicity, than for the certainty with which
it accomplishes the desired effect. It also serves to show that, in
every investigation of the operations of nature, the more minute
are our inquiries, the more will our admiration be excited by the
discoveries which we make. A superficial examination of any of
the works of creation must be sufficient to excite our wonder; but
an inquiry, successfully employed, in ascertaining the means by
which one, even of the least, important purposes of nature is
effected, cannot fail to excite a reverential awe, and dispose to the
adoration of the Great Supreme.

Yours, &c.

LETTER XXVI.

RECAPITULATION. ...APPARENT AGREEMENT Ofc THE HYPOTHESIS
WITH THE ECONOMY OF NATURE.

1 o enable you to form a clearer judgmenttof the opinion I have
delivered, respecting the formation of peat-bogs, coal strata, &c.
I will endeavour, in a recapitulatory sketch, to furnish you with an
uninterrupted statement of the means which, I imagine, nature
employs lor accomplishing these purposes.
VOL. i» MM

266

On every part of the earth, where vegetation takes place, and
where the surface remains for a long time undisturbed, a light
black earth will be found ; being the carbonaceous remains of the
Aegetable matters which have been there annually deposited, and
which have undergone the decomposing power of various succeed-
ing seasons. In those parts, where, in consequence of the meliora-
tion of the soil, by winter floodings, and the genial influence of
the sun's ardent rays, in summer, vegetation proceeds with rapi-
dity, there will the production of this vegetable earth not only be
more considerable ; but the same circumstances will be also favour-
able to the formation, destruction, and reproduction of myriads of
the smaller classes of animated beings, which inhabit the surface
of the earth, the waters, and the vegetables themselves. The sur-
face of the earth will here, therefore, at one season, be found teem-
ing in every point with animal and vegetable life ; at another sea-
son, it will be found richly impregnated with resinous, oily, and
other carbonaceous matters, which have been let loose, during the
decomposition of so many organized bodies of both kingdoms.

Thus, by the regular decay of the vegetables with which the
earth's surface is covered, and of the animals which they nourish,
are fit matrices formed, and appropriate nutrition secured, for suc-
ceeding generations. By forests falling through age, and obtaining
a covering from subsequent perishing vegetables, and being after-
wards pervaded by moisture, the formation of peat-mosses are easily
accounted for ; as well as the light loose earth with which these are
almost always covered, according to the poet, who, alluding to the
vast profits derivable from the digging of peat, and to the indica-
tion of subjacent peat, by the superficial light earth, says,

Est locus in Batavis, ubi nee gratissimus hoeres,
Terrain defuncto non velit esse gravem.

Epigram seu Enigma de Terra uliginosa*.

* Epigrammata Constantini Hugenii, lib. i.

267

But we have particularly to contemplate more sudden and exten-
sive changes, wrought by a deluge extending its power over the
whole surface of the earth. It is beyond the powers of the human
mind to conceive the prodigious changes which must have been
effectedduring this grand revolution. Receive then, with suspended
judgment, this slight sketch of some of the probable events of that
awful period.

By the spread of this overwhelming torrent over the whole sur-
face of the globe, forests must have been prostrated, mountains
broken down, and the waters of the rivers blended with those
of the ocean. During the stay of the waters on the face of the
earth, vast changes must also have been effected. Long-continued
submersion must have rendered the earth so soft and yielding, that
the pressure, united with some degree of agitation of this immense
bed of water, must have completed the subversion of the forests by
which the earth must have been nearly covered. Even during
the passing away of the waters, considerable changes would be ac-
complished. Whilst the waters were separating from the land,
the librating torrents would form for themselves new channels : their
beds, when cleared of their waters, would display vast and extended
valleys ; and their sides, mountains of an alpine height.

By the continuance of the waters, the upper surface of the strata
of subverted vegetable matters would necessarily become covered
by a muddy deposition, which would subside from the body of
water, by which it had been overwhelmed. On the passing away
of the water, the light substances which had floated on its surface,
amongst which would be various animal remains, would be depo-
sited on the muddy stratum which was already laid on the subja-
cent mass of vegetable matter. Thus would be formed a soil,
which on the passing away of the waters, would again promote a
rapid and luxuriant vegetation.

Such a tract would necessarily long remain free from the inter-

ference or culture of man : and previous to the complete depar-
ture of the water from it, would at certain times be liable to be
covered by inundations ; and at others, when left dry, would be
exposed to the heat of the sun. The plants peculiar to these two
different states might also be expected to be produced. Hence
equiseta, reeds, and other aquatic plants, would, at one time, fill this
spot, which at another would be covered with a variety of filices,
and of other plants peculiar to the open and sun-burnt heath.

Should the neighbouring mountains have contained iron, this,
dissolved by the various salts with which the water would be im-
pregnated, would be conveyed to spots where the water rested, and
where the decomposing organic matters were deposited ; and would
there be precipitated in the form of a brown oxide : this, uniting with
the superior and finer part of the earthy deposit, would cover the
decomposing vegetable matter with a stratum which, perhaps, after
no great length of time, would become that substance which is
known to mineralogists as bog-iron ore. But if, instead of the
water passing off, it should have long remained, and formed a large
and deep lake, then would other strata be successively added to
that which has just been mentioned. Sometimes these strata would
be furnished by the crumbled particles of the softer rocks, which
formed the sides of these immense and newly formed reservoirs ;
At other times, large masses of harder rocks would fall, undermined :
and, broken into pieces by the fall, would be sized and rounded into
boulders of various forms and magnitude ; or would be so far com-
minuted, as to be rendered the materials of future breccia, the
coarser sand-stones, &c. By the pressure of many of these suc-
ceeding strata, the lower ones would suffer a closer approximation
of their parts. The effects of this pressure are most observable in
those strata which have since become schisti, and which contain the
flattened remains of both vegetables and animals. The marks of
pressure are not, however, observable in all the strata, these effects

269
i
appearing to be much less general and extensive than might be

supposed, arising, probably, from each firmly-consolidated stratum
protecting the subjacent strata from the pressure of the accumu-
lating, superincumbent, mass. Other strata would be formed by the
coalescing particles of iron, and of argillaceous earth. These now
constitute the substances commonly called iron-stone, and which,
from their compactness and great degree of specific gravity, have
been supposed by many mineralogists to owe their origin to fire.

The strata of deposited vegetable matter, being thus secluded
from the air, by alternating layers of dense and compact stony
matter, would proceed, uninterruptedly, through the bituminous
fermentation ; during which it would be constantly permeated by
water impregnated with various saline, earthy, and metallic parti-
cles, derived from the several strata through which it had filtered.
Under the influence of these circumstances its conversion into coal
would be completed. Thus would a substance, particularly adapted
to the purposes of combustion, be formed from the eluvies of the
devastating deluge, and would be providentially heaped up in the
subterranean storehouses of nature, to be discovered in after-ages
by the curiosity and industry of man, when the spread of civiliza-
tion, by laying waste the vast forests which covered the earth,
should have considerably diminished the stock, whilst the increased
modes of consumption should have augmented the demand of
fuel.

When the very limited powers of our judgment are considered,,
which frequently are not even sufficient to satisfy us, respecting
the immediate or proximate cause of several of the most common
natural phenomena, we should be very cautious in proposing any
hypothesis, respecting the operations of nature, unless the regular
concatenation of cause and effect can be plainly traced ; and the
supposed final end is in exact accordance with our best ideas of
utility and wisdom. This caution is particularly necessary, if the

270

hypothesis is intended to point out a regular series of operations,
to mark their dependence, and, lastly, to infer the purposes, and
motives, which influenced the Creator, in making this particular
arrangement. Without such circumspection, there would be danger
lest, measuring the wisdom of God, by the scale of human
intellect, inferences derogatory to the divine dignity might be made ;
and plans and contrivances be imputed to the Divinity, not only
unworthy of omniscience, but originating only in misconception
and presumption.

But, it is hoped, that hypothesis which supposes the transmuta-
tion of vegetable matter into bitumen and coal, possesses the in-
ternal evidence of truth, since it presents to us a scheme, agreeable
to the phenomena we observe, and in which the economy of nature
is exercised, in a manner the most agreeable to the ideas we en*
tertain of a beneficent Providence.

Delightful indeed must have been the scene, which the earth
must have every where presented, immediately before the deluge.
Every hill and valley must have been clothed with luxuriant vege-
tation. But the moment of apparent destruction arrives : the lofty
forests, with which nearly the whole of the earth is supposed to
have been covered, are at once levelled : a world, which just before
was Elysium, is desolated, and rendered one vast mass of seeming
ruin. Torn up and carried away, by the force of the tremendous
torrent, the trees of the mountains are laid on those of the valleys,
and are together buried by the subsequent subversion of the moun-
tains themselves. Reflecting on such a scene of desolation, unpro-
ductive of any evident good, the mind hesitates, and feels a painful
dissatisfaction at being unable to imagine the origin of such a mass
of evil, without depreciating the wisdom, or the power of the Creator.
It is not, indeed, for me, deeply to agitate the abstruse and im-
portant question which is here involved ; but permit me to observe,
that when the power, the wisdom, or the benevolence of God, appears

271

to be deficient," the defect will ever be found in the powers of ob-
servation, and reflection of man, which do not enable him to dis-
cover the connection, between a comparatively small, or even only

apparent, evil, and a really great and important good. After a

short period the waters pass through their destined channels, and
the earth again becomes covered by the delightful verdure of vege-
tables ; fitted for the gratification of man, and for the support of
animal life. The vast forests, too, thus buried in 'the earth, instead
of mouldering into an inert and useless mass, still continue to per-
form an important part in the operations of nature. Instead of
having been destroyed, they are only changed : but so changed in
their forms and qualities, as with difficulty again to be recognized.
They have ceased, indeed, to live a vegetable life; but another
mode of useful existence is allotted them. Their constituent prin-
ciples are now so arranged, as to form a substance entirely new,
and different from any other which had previously existed; and
they are again made, after the lapse of a considerable period, to
contribute in another mode to the comforts and enjoyment of man.
Thus that which might once have appeared to have proceeded
from imbecility, or from a system of destruction, is at a distant
subsequent period shown to have been the result of supreme
wisdom ; which has ordained that every atom, as well as the
immense masses of matter, shall be continually suffering certain
changes, agreeable to those laws by which the universe exists. In
these processes of nature, the work of a supreme intelligence is
discovered ; and none can hesitate to say, with the poet,

NATURE is but a name for an effect,
Whose cause is GOD.

COWPER.

Yours,

LETTER XXVII.

MINERAL CHARCOAL. ...OPINIONS RESPECTING... .SUBTERRANEAN
COMBUSTION OF PIT-COAL. ...COMBUSTION OF PYRITES.*..
MINERAL CHARCOAL.

HAVING already taken some pains to prove, that the formation of
coal depends on the process of bituminization, it will of course
appear to you, that I have rather an ungracious task to execute,
when I now inform you that this letter must be devoted to the
description and history of a substance, MINERAL CHARCOAL, which,
though considered and described as a coal, does not manifest, on
the nicest analysis, the least trace of bitumen.

This substance, which possesses most of the external characters
of pit-coal, but, at the same time, agrees in all its chemical pro-
perties with charcoal, is thus described by Mr. Kirwan*, who,
anticipating the discoveries of Guyton de Morveau, conjectured it
to be the natural carbonic principle, as pure as nature generally
affords any principle.

Its colour is black, or greyish black ; its lustre approaching to
the metallic ; and its hardness, although it yields to the nail, ex-
ceeds that of chalk. It possesses no transparency, and breaks into
tabular fragments ; its fracture being foliated or slaty, and its cross
fracture flat conchoidal. It stains the fingers. Specific gravity,
from 1.4 to 1.53.

This substance is insoluble in acids. In a strong heat, it reddens,
but does not flame ; in a crucible, however, a slight bluish flame,

* Elements of Mineralogy, by Richard Kirwan, Esq. 1796, vol. ii. p. 49.

273

but without any sulphurous smell, is observed; undoubtedly from
the decomposition of water. Exposed to a porcelain heat for
several hours, in a closed crucible, it entirely or almost entirely,
evaporates like diamond. Under a muffle it is nearly consumed.
Distilled, it yields a small quantity of water; but no air, oil,
acid, nor alkali. Mixed with sulphate of pot-ash, it yields a liver
of sulphur ; and projected on red-hot melting nitre, it deflagrates
and alkalizes it : hence, Mr. Kirwan remarks, there is no doubt
but it is a combustible substance, possessing both the external and
internal characters of mere coal, or charcoal.

The Kilkenny coal is of this species ; its fracture being foliated,
and its fragments often coated with whitish illinitions. The culm
of Wales seems to be a variety of this species ; but less pure,
differing from it, chiefly, in being more brittle, and emitting, when
ignited, a disagreeable smell.

This substance yielded to Dr. Hutton, and the French chemists,
a strong corroboration of the opinion they had formed, respecting
the changes which bituminous substances, and particularly coal,
underwent from the influence of subterranean heat*. Knowing
that besides the common pit-coal, rich in bitumen, there existed
this substance also, in which no bitumen was discoverable, they con-
sidered the former kind, as abounding in the oily matter which had
been contained in the various organized bodies, from which it had
derived its origin : and concluded, the latter to have been exposed
to a considerable degree of subterranean heat, in consequence of
which, it had suffered a deprivation, by distillation, of its bitumen;
it being thereby left a caput mortuum, or perfect coal. The exist-
ence of the purer bitumens, in separate situations, has been also
reckoned in evidence of the propriety of this theory. Thus Dr.
Hutton mentions, as an instance of the separate existence of these

* Theory of the Earth, with Proofs and Illustrations, by James Hutton, M.D. 1795.
VOL. I. N N

volatilized bituminous matters, a stratum of Jime-stpne, near Raith,
in Fifeshire, which, though but slightly tinged with 3, black colour,
contains bituminous matter like pitch, in many cavities wtich are
lined with calcareous spar crystallized.

Dr. JIutton's opinions respecting the changes produced on sub'
terranean bitumens, by tl^e agency of fire, may be comprised in
tfyese two positions; first, That the purer and fluid bitumens are.
proceed by distillation frpm coal ; secondly, That the Kilkenny
coal, an4 other sijujjjar natural coke, is the residuum of this distil*
lation. In refutation of the first of these positions, which has been
also endeayoure4 tp be supported by most of the French chemists,
Jjttle requires to be said, except to remark, that the quantity
of t^e fjuid, and purer bitumens, naphtha, petroleurn, asphaltum,
$;c. which ha$ been found, far exceeds the proportion of such, coal
as, with all that diligence of research which so useful an article has
excite(|, has been discovered tp have suffered this spoliation. But
that this substance is common coal, deprived of its bituminous
matter by heat, I acknowledge, seems at least to be probable.
When we contemplate the situations in which coal mines are placed,
enclosed on almost every side by strong barriers of stone, by which
the access of atmospheric air is almost entirely prohibited, we can-
not but conclude, that, should a seam of coal become ignited, the
coal must be completely charred, as far as its combustion extends.
That it furnishes any evidence in favour of all coal having beei*
exposed to the fusing power of heat, I acknowledge I do not per-
ceive ; but merely that such particular masses of coal have been
subjected to fires. It also shows, that such is the wise provision,
made, in this case, that, although a substance, formed to supply
mankind with fuel, should casually be subjected to the premature inr
fluence of fire, it shall still continue fitted for the purpose for which
it was originally intended : the very material changes, which it has
undergone, having even rendered it more highly useful, for certain

275

purposes, than it had been in its original state. Mr. Kifwatt, how-
ever, who will not allow that the Kilkenny coal has suffered any
change by the action of fire, justly observes, " Would not bitumen
be found in the neighbourhood of those beds of coal from which it
had been expelled ? Would not the sulphur also be distilled from
the pyrites found in the coal ? Yet neither in the coal mines of
Kilkenny, the coal of which is, of all others, most completely des-
titute of bituminous matter, nor any where near them, is the least
trace of bitumen to be found ; and the pyrites remain in their
usual integrity/'

Every endeavour to account for the formation of this mineral
carbon, meets with considerable difficulties ; neither the Neptunian
nor the Plutonian system appearing, in the present state of our
knowledge, to be sufficient, separately, to explain the circum-
stances attending the production of this substance.

As to the operation of fire, it must be admitted, that the com-
bustion of a vein of coal might take place, under such circumstances
of prohibition of the access of atmospheric air, as might, most pro-
bably, secure the reduction of the coal to a char. The probability
of the Kilkenny coal having been thus formed, derives some aug-
mentation from the spontaneous, as well as accidental, burnings
of strata of coal, which, even of late years, have been noticed, as
having occured in several parts of the world. Thus Cambden speaks
of a coal mine in Newcastle, which was burning for several years ;
and according to the account of Mr. Jefferson, who wrote in the
year 1787, a bed of coal at Pittsburg, in North America, was then
burning, and had been on fire since the year 1765*. Another coal-
hill, on the pike-run of Monongahela, had then been burning ten
years, and had burned away about twenty yards only. The Abbe"
Raynal also relates, that a vein of coal was set on fire at Cape
Breton, which burned with great fury.

* Jefferson's State of Virginia, p. 43.

276

In the grounds at Benwell, about a quarter of a mile north of
the river Tyne, a coal mine took fire at a workman's candle, negli-
gently placed, and continued burning about thirty years, though
at first so small, that a proposal was made to put it out for so low
a reward as half-a-crown, but it was not accepted. It afterwards
acquired such force and strength, Mr. Wallis says, from the kindled
sulphurs and bitumens, that it raged with fury, in various directions
and depths ; sometimes taking its course east and west, and at last
to the north, into the grounds of Fenham, near a mile from its first
appearance: committing great ravages in its way; and being only
conspicuous by its flame, and columns of smoke, in the night.
The eruptions at Fenham were in nearly twenty places*.

Nor is it from accidents only that combustions of this kind
occur. Mr. Williams states that, within a mile of Kirkaldy, in
Scotland, in a great plain, called Dysart Moor, the coal, which is
there found in plenty, burns almost spontaneously — Sometimes
flames are seen in the night, and a black smoke in the day — The
inhabitants say, that at approach of storms, dreadful hissing noises
are heard from the holes and caverns, with a considerable discharge
of flame. Nor is it beds of coal only, that a slow combustion would
convert to mineral coal, as Mr. Kirwan calls this charred coal;
since a similar substance might probably be formed by the burning
of peat, the stratum covering which might so regulate its burning,
as to secure its charring. In addition to the instances, mentioned
in a former Letter, of these accidents, I will relate one, mentioned
by Abbe Fortis, who says, " Not many years ago, a fen, near the
village of Ostrovizza, was struck with lightning, and, its bottom
being turf, it burned a long time under ground, though the fire was
visible only in the night; after it was extinguished, the whole ferx
remained black, and the upper soil became barren -)-."

* The Natural History of Northumberland, vol. i. p. 132.
f Travels in Dalmatia, p. 37.

27?

Indeed the very considerable disengagement of heat, during the
decomposition of pyrites, will easily account for the natural accen-
sion of so combustible a body as coal, if in union with it whilst
such a process is going on. Thus Dr. Jordan, speaking in his Essay
on Mineral Waters, of the properties which coals possess, when
they contain much of the pyrites, or, as the colliers say, coal-
metal, of heating and even kindling upon the gradual accession of
moisture, or the affusion of water upon them, states, that several
such accidents have happened at Newcastle ; and he particularly
mentions a circumstance of this kind having occurred in London,
at Puddle-dock. Dr. Plott relates*, that at Ealand, in Yorkshire,
one Wilson having piled up many cart-loads of pyrites in a barn of
his own, for some secret purpose, perhaps to extract the gold, the
roof being faulty, and admitting rain-water to fall copiously in
among them, they first began to smoke, and at last to take fire, and
bum like red-hot coals, so that the town was considerably disturbed
and alarmed.

To effect the dissipation of a considerable portion, if not the
whole of the inflammable matter, from vegetable and bituminous
masses, such a degree of heat may perhaps be sufficient as may
neither render the mass, nor the vapours which evolve from it,
luminous, but during the darkness of the night. The phenomena
described in the following account, related by John Stephens, M.A.
in the Philosophical Transactions -f, seems to point out such a gra-
dual decomposition of pyrites; and which, by charring the included
combustible matter, might be competent to the formation of the
peculiar coal here treated of. Mr. Stephens says, " that in the
month of August, 1751, the air, having been for some time remark-
ably hot and dry, was changed of a sudden by a heavy fall of

* The Natural History of Staffordshire, by Dr. Thomas Plott, p. 142,
t Philosophical Transactions, vol. lii. p. 119.

278

and a high south-west wind. The cliffs near Charmouth, in the
western part of Dorsetshire, presently after this alteration of the
atmosphere, began to smoke, and soon after they burned, with a
visible, though subtile flame, for several days successively; and
continued to smoke, and sometimes to burn, at intervals, till the
approach of winter ; nay, ever since that time, especially after any
great fall of rain, thunder and lightning, or a high south-west wind
(which drives the sea with great violence against the cliffs, and beats
off large pieces of them), the cliffs continue to smoke, and some-
times to burn with a visible flame, which, during the summer months,
is frequently observed in the night-time. On examining these cliffs,
in the year 1759> I discovered/' he says, " a great quantity of
pyrites, not in any regular strata, but interspersed in large masses
through the earth, and which proved to be martial ; of cornua am-
monis of different sizes, and other shells, but of the bivalve class,
which were covered over, and mineralized,as it were,with the pyritical
matter ; of belemnites, also crusted over with the like substance :
and the cliffs, for nearly two miles long, and from the surface to
thirty-five or forty feet deep, even to the rocks at high-water mark,
were one bed of a dark-coloured loam, strongly charged with bitu-
men. Moreover, I found also, he says, a dark-coloured substance,
resembling coal cinder ; some of which being powdered, and washed
in distilled rain-water, upon filtrating the water, and evaporating it
to a pellicle, its salts shot into fine crystals, and appeared to be no
more than a martial vitriol ; one ounce of this cinder-like substance
yielding one drachm of salt. I gathered up about one hundred
pounds weight of the different kinds of those pyrites, marcasites,
&c. which were laid up in a heap, exposed to the air, and every day
sprinkled with water : the consequence was, that, in about ten days
time, they grew hot, soon after caught fire, burned for several hours,
and fell into dust.

" When the cliffs were observed to burn in the night-time, the
flame was plainly perceived by a spectator at a distance ; but when
he drew near to the place, seemingly on fire, he could perceive a
smoke, but no flame. In the day time, nothing but a smoke wa»
perceived, except the sun shined ; when the cliffs appeared, ^t a
distance, as if they were covered with pieces of glass, which re-
flected the sun's meridional rays ; but, upon drawing near to the
places where these luminous appearances were perceived, they dis-
appeared, and the cliffs seemed to be covered with smoke, which
stunk of a bituminous and sulphurous matter.

" I have also, he says, been an eye-witness of the same kind of
flame arising from the Lodes, in Cornwall, especially such as con-
tained a great quantity of mundic and martial pyrites. Three times
I have seen this flame arise from the earth in the night, and once in
the middle of the day. In the night, a person, standing at a little
distance, would imagine that the place was all on fire ; and, even
on drawing near the same, he perceives himself surrounded with
flame, but is not hurt ; and, in four or five minutes time, he per^
ceives this flame to decrease, and fall into the earth. In the day-
time, the flame is of a different colour, and not much unlike the
flame which arises from a furnace. There are several mines disco-
vered in this country by these mineral fires, where there were na
symptoms of such mines before."

Several writers have mentioned, with surprise, the circumstance of
a substance having been frequently found at considerable depths,
which exactly resembles burned wood or charcoal ; and which many,
unable to ascertain its origin, have described as MINERAL CHAR-
COAL. Wood that appeared to have been burned was found by
G. F. de Oviedo, in earth which did not appear to have been ever
dug or disturbed, at a considerable depth, in the mines of Peru *.

* Purchases Pilgrim, lib. v. cap. iii. p. 911.

280

Dr. Woodward thus describes a specimen in his collection* : " A
piece of wood having manifest marks of its having been charred, or
burned by the fire, before it was buried in the earth. It is not
unusual to meet with wood, thus burned, reposited in the bowels of
the earth/'

In the copper mines of the Ryphean mountains, in Siberia, and
in the neighbourhood also of Cazan, the copper is found united
with blend, sand, and wood, forming a hard and compact mass.
The vegetable parts are so brittle as to be easily detached ; the
wood being black, resembling a charcoal -f.

The Abbe Fortis relates, that in Luzzane, on the side of the bed
of the torrent called Gipalova Vrilo, he found the roots and trunk
of a tree, three feet in circumference, reduced to a fossil coal. The
particularity by which this coal trunk was distinguished, was its
having been cut, little more than a foot above the root, by a hatchet,
or some other similar instrument before the marine strata covered it.
I leave, the Abbe says, to those who are more knowing than myself,
to decide by how ancient a hatchet this tree has been cut, and in
what times those lands have been covered by the waters of a sea
now far from us, and which has left behind it a prodigious quantity
of exotic testacei. — In the accompanying gravel are heavy pieces
of lava, sometimes black and sometimes grey, fossil coal, and bi-
tuminous scissile earth.

Mr. Cramer, Counsellor of Mines at Altenkirchen, in the second
volume of Der Gesellschaft Naturforschenda Freunde zu Berlin Neue
Schriften, relates, that in the county of Wachtersbach, in the princi-
pality of Isenberg-Birstein, under the exterior crust, there first occurs
a strong stratum of white and red sand-stone, in alternate order,

* Catalogue of English Fossils, part h. p. 19.

t Voyage en Siberie, en 1761, par Mons. 1' Abbe" Chapped' Auteroche, tome i. partie ii.
p. 671.

281

which extends to the distance of several miles in the neighbourhood.
Under this lies a grey argillaceous stone, which feels somewhat
greasy, soft, and friable, and is scarcely three inches in thickness.
Below this there is a stratum of excellent iron-stone, of equal thick-
ness, the bottom of which consists of solid sand-stone, of a kind of
mill-stone, which often occurs in these districts. This iron-stone is
different from every other kind in the neighbourhood ; it is a com-
pact argillaceous iron-stone, of a reddish brown colour, and of a
rough fracture, sometimes mixed with shells ; among which there is
found, though very seldom, a variety which has a fibrous fracture,
with an almost metallic splendour, and seems worthy of further
examination. When I visited this work, he says, some masses of
this compact iron-stone were dug up, which contained charcoal.
This charcoal was found loose in the iron-stone, and partly grown into
its substance, and adhering to it. By what natural, or artificial fire,
this charcoal was burnt, or by what singular revolution it was car-
ried into the depth of from three to four fathoms, and there so inti-
mately combined with the iron-stone that it seems to form one body
with it, he observes, no mineralogist can with certainty explain.

The hypothesis which Mr. Cramer formed respecting this singular,
and certainly uncommon subterranean mixture, is, that the charcoal
was burnt, in the neighbourhood, either in the usual manner, or by
natural fire, and that some fragments of it, by some convulsion of
nature, were thrown to the above depth, where they united with
the ferruginous matter, and by these means produced the above
remarkable phenomenon. On many fragments one can observe the
transition of the not completely burnt wood into iron-stone; even
the bark of the wood, actually converted into iron-stone, may be
clearly distinguished ; and the perfectly black natural, or artificial
charcoal, possessing all the properties of the charcoal of burnt
wood, lay undecom posed in it. — This iron-stone, Mr. Cramer adds,

VOL. i. oo

282

is exceedingly easy of fusion ; and so much so, that it is used as a
flux for other kinds *.

Pieces of this mineral charcoal are frequently to be seen, in the
deep stratum of blue ferruginous clay dug for tile-making, near
Hackney-road : an examination of this substance, and of that which
forms the stratum in which it is found, seems to point out the cir-
cumstance, from which the important change it has experienced
has proceeded.

Under about a yard of mould, and as much yellow clay, there is
in general found about this spot, a layer of variously sized gravel, and
silicious sand, extending from twelve to fifteen feet in depth, and
coloured in every part by a yellow oxide of iron. Beneath this is the
stratum of blue ferruginous clay, which is now dug to the depth of
twenty -two feet without showing any appearance of termination.
This clay, which seems to have been the muddy deposit of a stand-
ing water through many ages, has in almost every part of it small
particles of pyrites, which are sometimes formed into pretty large
nodules ; these larger masses, in general, investing pieces of charred
wood. Similar pieces of wood, but without this investiture of
pyrites, are here also frequently met with : the whole mass of this
structure appearing to be made up of clay, intermixed with pyrites
and altered vegetable matter.

The change which this wood has suffered appears to have been
produced by the heat resulting from the decomposition of the
pyrites in which it had been imbedded.

Yours, &c.

* Phil. Mag. No. xlix. June, 1802.

283

LETTER XXV11L

PYRITOUS WOODS. ...OPINIONS OF DR. HUTTON AND MR. PLAYFAlR
....IGNEOUS ORIGIN. ...AQUEOUS ORIGIN EXAMINED.

1 CONSIDER your claim as too well founded to allow me to impute
to you impatience. You requested from me a history of the sub-
stances generally termed extraneous fossils ; and during a long cor-
respondence, carried on in consequence of that request, I have not
yet given you the history of a single substance, which general opi-
nion allows- to be thus classed. The substances on which I have
hitherto dwelt, I have taken the liberty, contrary to general opi-
nion, to consider as extraneous ; or, as I term them, secondary fos-
sils; and, therefore, must refer you to the arguments which I have
adduced, in support of that opinion, for my justification, in detain*
ing you so long in their examination.

The establishing of the right of these to the rank of secondary fos*
sils, is not, however, the whole of what I hope to have accom-
plished. I have also endeavoured, at the same time, to ascertain
the most general basis, or substratum, of vegetable fossils ; my suc-
cess in this respect, however, still remains to be determined.

The subject of the present Letter cannot but prove highly inte-
resting, being the conversion of wood to a splendid metallic sub-
stance ; in which, although sufficient traces of its original mode of
existence are discoverable, the transmutation is such that its supe-
rior gravity, as well as, often, its lustre, proves that it now contains a
considerable portion of metallic matter. To give a slight sketch of
the histpry of these bodies, as far as respects the various appear-

284

ances they yield, the parts in which they are found, and the nature
of the change they have suffered, I shall therefore now attempt.

The vague manner in which the metallization of wood has been
hitherto endeavoured to be accounted for, will excuse me for ex-
tending this inquiry to a more than usual length. M. Walch*
who paid particular attention to this subject, says, the wood is, in
general, metallized, in those places, where the subterranean heat
raises a considerable quantity of metallic vapours ; and, upon these
vapours meeting with solid bodies, they deposit their metallic par-
ticles. Water, impregnated with metallic particles, he also sup-
poses, may convey the particles of metal into the interstices, and
cavities of the wood.

It must be confessed, that considerable difficulties are to be
opposed, whilst endeavouring to determine the real nature of the
operation, by which a substance, which originally existed in an
organized state, has been so changed, as to be rendered metallic in
almost every part. Chemical analysis, as well as the natural de-
composition of these substances, shows that they are composed of
a portion of the ligneous substance, in most instances rendered
charcoal, intermixed with pyrites, or some saline metallic body.
The pyrites are frequently in so considerable a quantity, as to suf-
fer hardly any diminution of its metallic splendour from the inter-
mixed charcoal, which still serves to show the striae and circles,
which characterized its original structure. An inquiry into the
nature of the operation, by which this change has been effected^
must necessarily involve in it the question — by what natural ope-
ration are pyrites formed ? This question should, therefore, first
engage our attention.

The formation of native metallic sulphurets, pyrites or marca-
sites, has been adduced, by Dr. Hutton, as clearly evincing the
agency of fire, and as entirely incompatible with aqueous solution.
The doctor says, speaking of the union of metallic substances with

285

sulphur, " This mineralizing operation is performed by heat or fu-
sion ; and there is no person skilled in chemistry, that will pretend
to say this m&y be done by aqueous solution*/'

Professor Playfair, who has given his powerful support to Dr.
Hutton's theory, speaking of these substances, metals in the form
of an ore, mineralized by sulphur, says, " Their union with this
latter substance can be produced, as we know, by heat, but hardly
by the way of solution, in a menstruum; and certainly not at all,
if that menstruum is nothing else than water. The metals, there-
fore, when mineralized by sulphur, give no countenance to the hy-
pothesis of aqueous solution : and still less do they give any, when
they are found native, as it is called, that is, malleable, pure, and
uncombined with any other substance. The great masses of native
iron found in Siberia, and South America, are well known ; and
nothing certainly can less resemble the products of a chemical pre-
cipitation. Gold, however, the most perfect of the metals, is found
native most frequently : the others more rarely, in proportion nearly
to the facility of. their combination with sulphur. Of all such spe-
cimens it may be safely affirmed, that if they have ever been fluid,
or even soft, they must have been so by the action of heat ; for to
suppose that a metal has been precipitated, pure and uncombined
from any menstruum, is to trespass against all analogy, and to
maintain a physical impossibility f.

In a science like chemistry, in which, from the multiplicity of its
subjects, and of their operations upon each other, important disco-
veries are daily being made, change of opinion must, necessarily,
be frequently submitted to, by ^the most intelligent. Hence also it
happens, that apparently established theories, of the most learned
men, are sometime subverted by those whose general knowledge
in the science is much less considerable, but whose application

* Theory of the Earth, vol. i. p. 63.

t Illustration of the Huttonian Theory, p. 58.

of some recent discovery has happened to have been fortunate.
Thus the opinions entertained by Dr. Hutton, and by Dr. Playfair,
respecting the formation of pyrites, and the precipitation of pure
metallic substances, I trust, will be no longer tenable, when com-
pared with the ingenious experiments and observations of still more
recent date.

The union of metals with sulphur, without the aid of fire, is dis-
coverable in many instances. A familiar instance is the violet tar-
nish which attaches itself to polished silver ; and which, being al-
lowed to accumulate, will form a crust which may be separated by
bending the silver, or striking it with a hammer. This pellicle has
been examined by Mr. Proust, who asserts it to be a sulphuret of
silver. The common sympathetic inks, formed of metallic solu-
tions, the writing of which, before invisible, is immediately dark*
ened by sulphuretted hydrogen, is also an instance of the union of
metal and sulphur, in the moist way. So also is that kind of shining
pellicle which forms on wainscots, painted with white lead, and which
have been exposed to the influence of sulphuretted hydrogen.

An observation of Dr. Thompson, in his excellent System of Che-
mistry, affords us very decided evidence on the question which we
are about to discuss ; which is, Whether the natural combinations
of sulphur with the metals are effected, by means of fusion by heat,
or by solution by water ? Speaking of a combination of sulphur
with copper, he says, " This compound may be formed by mixing
copper filings and sulphur, and making them into a paste with
water, or even by mixing them together, without any water, and
allowing them to remain a sufficient time exposed to the air, as I
have ascertained by experiment*/' This point is also illustrated
by the well-known artificial earthquake of Lemery, in which a
mixture of equal parts of iron filings and of sulphur, being

* A System of Chemistry, by Thomas Thompson, M. D. vol. i. p. 117.

287

moistened with water, and buried in the earth, is said to under-
go so considerable a degree of expansion, as to make the earth,
over it, heave and crack, in several places ; from which even fire is
said sometimes to burst. Fourcroy, indeed, states, that this expe-
riment did not succeed with Bucquet. But, whether the experi-
ment succeeded to the extent described by Lemery, or not, is by
no means essential to our inquiry, since it is sufficient for our pur-
pose, that, when the experiment is made on a very small scale, the
mixture heats and swejls, sulphuretted hydrogen escapes, and the
more fixed principles enter into intimate union.

Perhaps neither of the above experiments affords an instance of
the union of the pure metal and sulphur : in the latter experiment
it seems obvious that this is not the case ; and in that related by
Dr. Thompson, it appears highly doubtful. Still an examination of
the changes which may be supposed to be effected, in these experi-
ments, will place the subject in a more clear point of view. The water
is undoubtedly decomposed ; its oxygen combines with the metal and
with the sulphur, forming a metallic oxide and the sulphuric acid ;
and these uniting, form a solution of the metal in the sulphuric
acid. The separated hydrogen attaches to itself in its nascent
state, a portion of sulphur, and becomes sulphuretted hydrogen gas.
Admitting that, in neither of these instances, an union of the two
simple substances, the metal and the sulphur, is proved to take
place ; still, I trust, these experiments show that a saline combina-
tion of these two bodies may be formed, in subterranean situations,
merely by the aid of water. This being ascertained, it remains to
discover, whether from this compound, and the other substances,
necessarily present, a metallic sulphuret is not likely to be formed.

The changes which we are to contemplate, then, are those which
would take place in a saline metallic solution, exposed to the in-
fluence of sulphuretted hydrogen, and the surrounding carbona-
ceous substances. By the addition of sulphuretted hydrogen to;

288

solutions of the metals, it has been found that a conside able pre-
cipitate ensues ; and the precipitate thus made, is found to be com-
pounded of the metal and the sulphur. The sulphuret thus preci-
pitated is black from silver, yellow from bismuth, brown fron,
copper, &c. Thus also, in subterranean situations, similar effects
ensue from the agency of the sulphuretted hydrogen on the solution
of the metal. The action of a double affinity is exerted. The dis-
solved and oxydated metal, as well as the sulphuretted hydrogen,
suffers decomposition. The sulphuretted hydrogen being separated
into its two constituent principles, hydrogen and sulphur, the former
unites with the oxygen, which had oxidated the metal and had con-
tributed to its solution, abstracts it from the metal, and with it forms
water ; whilst the latter principle, the sulphur, deserted by the hy-
drogen, combines with the metal, thus nearly freed of its oxygen,
and reduced, and forms with it a sulphuret, which is precipi-
tated.

Iron, water, and sulphur, either now exist, or have left traces of
their existence, in almost every subterranean situation; and there is no
difficulty to oppose the supposition, that, in such situations changes
and combinations may have ensued, resembling those which we
have just described. One material difference would, however, arise;
the sulphuretted hydrogen, prevented from escaping, must have
penetrated, and .forcibly exerted its influence on, every particle of
the metallic solution. This would also be acted on by the sur-
rounding, as well as by the mingled, carbonaceous, and earthy or
alkaline matter. The oxygenized sulphur and metal, thus acted on,
at once, by these deoxidating powers, must each have given up the
portion of oxygen attached to them ; which, with the hydrogen,
would form water; whilst the pure metal and sulphur, entering into
intimate union, would form pyrites, possessing a metallic lustre.

It is here proper to remark, that the very ingenious experiments
of Mrs. Fulhame show clearly, the powerful influence of water, in

289

promoting the reduction of metals, and in giving to them their
peculiar lustre, at a temperature even below that which the atmos-
phere ordinarily possesses*.

Hence it appears probable, at least, that the formation of the
native sulphurets may take place, independent of the action of fire:
and M. Proust, and our celebrated countryman, Mr. Davy, are of
opinion, that the native sulphurets are actually formed, in conse-
quence of a similar decomposition of different solutions of metals,
by their combination with hydrosulphurets. It must, however, be
remarked, that some of the metals are not thus precipitated by the
addition of sulphuretted hydrogen alone ; since when the metals
are reduced to their minimum of oxygen, in consequence of its sub-
traction by the hydrogen, they retain the last portion of it with a
considerable degree 'of power, and are thereby prevented from en-
tering into union with sulphur. The addition, however, of an earth,
an alkali, or the carbonaceous matter, so abundant in the earth,
takes from the metal this portion of adhering oxygen, leaving it
pure, and free to enter into combination with the sulphur. Injus-
tice to the supporters of the Vulcanian theory, it must be also
remarked, that essentially different properties, both physical and
chemical, distinguish the pyrites, or native sulphurets, from the
artificial or factitious. Their crystalline forms, their peculiar splen-
dour, and their iridiscent investiture, yield matter, indeed, for per-
tinacious argument, on both sides of the question. But, surely, the
circumstance of these crystals being found, often, fast imbedded in
so combustible a body as bitumen, speaks strongly in favour of
their aqueous origin. Jet is frequently found containing them, or
being closely invested by them, and at the same time manifesting
no marks of having been acted on by heat ; which would surely
have been the case, if their formation, which must have been at the

* An Essay on Combustion, by Mrs. Fulhame, p. 178.
VOL. I. P P

290

time of their fixing themselves in, or attaching themselves to, this
substance, had been effected from a substance, in a state of igneous
fusion. Their splendour, and their iridiscent surface, appear also to
be at least, as Easily accounted for by the agency of water, as by
that of fire. Mrs. Fulhame has detailed some very pleasing, and in-
genious, experiments, which bear very strong evidence in favour of
this opinion of their aqueous origin. This lady impregnated pieces
of silk with solutions of various metals, and exposed them, wetted
with water, to the action of hydrogen, sulphuretted hydrogen, Sec.
inconsequence of which they became covered by films of reduced
metal; which sometimes, like the native sulphurets, displayed a
variety of most lively colours. Even those metals, which were
not capable of being precipitated, by the addition of sulphuretted
hydrogen to their solutions, obtained, in this manner, their metallic
splendour*.

By these experiments, we are undoubtedly taught, that hydro-
gen, as well as sulphuretted hydrogen, is capable of reducing the
metals, even in the ordinary temperature of the atmosphere ; that
water promotes these reductions in a very remarkable manner ; and
that these reductions of the metals are accompanied by a variety of
colours, resembling those which frequently mark the surfaces of the
splendid natural sulphurets, or pyrites.

A series of experiments, ascertaining the effects of hydrogen and
sulphuretted hydrogen on various solutions of the different metals,
aided by the deoxydating powers of carbon, alkalies, and earths,
would, it seems reasonable to expect, manifest, in the hands of the
able chemist, that the formation of the brilliant, crystallized, me-
tallic pyrites, has depended on aqueous solution. But the vast mass
of materials, the great quantity, as well as the density of the super-
incumbent strata, which must necessarily prevent any escape of the

* An Essay on Combustion, p. 36.

291

sulphuretted hydrogen ; and the long continuance of this substance,
in contact with the other principles, must give so superior a degree
of energy 4o the natural processes, by which these substances are
formed, as, perhaps, would leave to art, the power of only approx-
imating to their result.

I have already furnished you with some particulars, respecting
the form and appearance of pyritous wood, as well as concerning
the situations in which it is commonly found. But as the follow-
ing account, written upwards of a hundred years since, by Pillingen,
whilst treating of the bituminous wood of Meizlibizen, is exceed-
ingly particular and comprehensive, and was written, without the
inten tion of supporting any opinion resembling that which I have
here advanced, I have laid it before you, that it may serve as
a test, to show how far the conjectures which I have formed, re-
specting its formation, are supported, or opposed, by the circum-
stances under which this substance is found. A pit, he says, was
lately dug in the declivity of the mountain, directly to the vein of
bitumen, for the more easy extraction of the substances which were
dug. Here they first found, for about three feet from the surface,
common earth, with which a small portion of sand was mixed :
they then dug, to the depth of two orgyia, through a vein of very
tine clay, which was sustained by a firm sand, impregnated through-
out, and blackened by bituminous vapours. At last, when they
came to the surface of the bituminous earth itself, behold ! pyrites
of a most uncommon form presented themselves to view ; so fabri-
cated, had they been in the bowels of the earth, that their external
appearance, in every respect, agreed with that of decayed wood.
Other portions had other appearances ; for some resembled stakes ;
others were so incircled by the knots of branches, &c. as to appear
like smooth, cylindrical, and oblong sticks : some again, hollowed
out, were woody on the concave inner surface, whilst the external
and convex surface was brassy ; others were turned, twisted, sur-

292

rounded, and enveloped in such various fantastic forms, that the
most expert artist could hardly have depicted them all. Lastly,
some were only partly pyritous, and others were formed entirely by
a very hard and heavy pyrites of a silver hue. By a reference to
Plate VI. Fig. 1, 23,27, and 29» a more correct idea may, perhaps,
be obtained of the forms which Piilingeii here describes.

o

In a former part of our inquiry, it was endeavoured to be proved,
that bituminization is the first essential process, in the mineralization
of vegetable matter; and now, I trust, it has been shown, that the
further mineralization, the metallization of vegetable matter which
has been thus bitnminized, is very likely to result from its union
with certain substances which are, or have been, present, in a state
of fluidity, in most subterranean parts of this globe. Reflection on
the changes which must take place in wood softened by the bitu-
minous fermentation, and permeated thoroughly by a solution of
iron in the sulphuric, or sulphurous, acid, will enable us to form a
more correct judgment on this point. These changes would not
much differ from the following. The abundance of hydrogen,
possessed by the bituminous wood, would occasion a deoxydation
of the metal, and of the sulphur, which had been carried into
contact with it, in a state of solution ; the greatest part of the car-
bonaneous matter of the wood remaining. Repeated minute ex-
amination of metallized woods have clearly shown to me, that their
structure is exactly agreeable to this supposed mode of their for-
mation. The circles and striae, which give the characteristic ap-
pearance of wood to these substances, are evidenly formed of the
ligneous fibres converted to charcoal, whilst all the intermediate
spaces are filled with the brilliant metallic matter.

According to the hypothesis, here endeavoured to be supported,
the vegetable substance, at first, suffers a thorough penetration with
moisture ; it then is submitted to the influence of the process of
bituminization, by which it passes through various degrees of soft-

293

ening, even in some instances amounting to liquefaction. The last
change which it undergoes is produced, during that softened state,
by the addition of the saline im tallic solution, of which we have just
been speaking. From this long continuance, in a softened state,
and from the pressure of the superincumbent matters, we may rea-
dily account for this species of mineralized wood being found,
almost always, in a compressed state, and for its having undergone
this degree of compression, without having suffered any degree of
fracture.

I do not, indeed, wonder at the scepticism which you say our
friend Wilton displays on this occasion ; since several very learned
men have been induced, by a consideration of this circumstance,
its oval compressed form, differing so much from the round shape
of common wood, to believe it to be entirely of subterraneous ori-
gin; and that this compressed form was the grand characteristic of
wood of subterranean growth.

But in many specimens of this kind of wood, such as those at
Plate VI. Fig. 1, and Fig. 7' so few of the ligneous fibres are dis-
coverable, that a section of them displays an almost uninterrupted
metallic surface. To explain this circumstance, it is only necessary
to consider that, in this case, there must have been a loss of the
ligneous fibre, which may be easily supposed to have taken place,
not only by the mechanical action of the water, whilst passing
through it ; but also at the time of the formation of the pyrites,
when some of the carbonaceous particles undergoing a degree of
oxygenation, and assuming a gaseous form, are employed in the for-
mation of carbonic acid ; whilst other portions, uniting with hydro-
gen, might contribute to the formation of carburetted hydrogen.

I find myself, I acknowledge, much more disposed to concur with
him in his opinion, that the frequent discovery of a metallic sub-
stance, in a vegetable form, might have furnished the poet witii the

294

'

idea of the transmutative power, with which he favoured the Phry-
gian king. The following lines seem to corroborate the opinion ;

Vixque sibi credens, non alta fronde virentem
Ilice detraxit virgam : virga aurea facta est.
Tollit humo saxum ; saxum quoque palluit auro.
Contigit et glebam ; contactu gleba potenti
Massa fuit. Arentes Cereris decerpsit aristas ;
Aurea messis erat. Demtum tenet arbore pomum ;
Hesperidas donasse putes.

METAMORPH. lib. xi. 1. 108.

There are, undoubtedly numerous appearances, which would lead
to the thought of such a transmutative power. Besides stones and
earth, we have just seen a realization of the metallic twig ; and shall
have occasion afterwards to point out some specimens, which dis-
play such appearances as have occasioned very learned men to
adduce them, as instances of the conversion of corn and fruits into
a metallic substance.

You will, I suspect, deem this letter too long ; in apology, I must
remind you, that the task which I have endeavoured to perform is
of importance, and, in attempting to establish the aqueous origin
of pyrites, I have had to oppose those opinions, which the learning,
and the zealous exertions, of their promulgators, have stamped with
the highest authority. The strong ground, on which the opinion
here opposed, is supposed to be established, may be gathered from
the words of Mr. Play fair, who, speaking of pyrites, asserts it to be
" a substance that is, perhaps, more than ony other, the decided
progeny of fire*.1'

Yours, &c.

* Page 33.

295

LETTER XXIX.

PETRIFACTION THEORIES RESPECTING SUBSTITUTION

ADOPTED BY WALCH, KIRWAN, DAUBENTON, FOURCROY, &C.
....THEORY OF DR. HUTTON AND MR. PLAYFAIR.

ALTHOUGH the truth of your daughter's and our friend's observa-
tion must be admitted, that you have been detained a long time
from the consideration of the grand object of your inquiry, the
nature and formation of petrifactions ; yet I will not, for a moment,
admit the justice of the charge, that this has been done unnecessa-
rily. On the contrary, I flatter myself that it will appear, that the
process of bituminization, on which we have so long dwelt, has
been the preparatory process to that of petrifaction, in most of the
vegetable substances which have undergone this species of change.
But, as the opinion I propose to offer, respecting the petrifaction of
vegetable bodies, differs materially from the theories which have
been framed by those, who are deservedly considered to be the first
authorities in inquiries of this kind, I think it necessary, in the first
place, to give you a sketch of those theories ; and then to lay before
you that hypothesis, which, according to my judgment, accords
best with the several phenomena which these bodies yield.

The earliest attempt to account for the petrifaction of wood, on
chemical principles, proceeded on the idea, that the fixed, earthy,
parts of the wood, deprived of their watry, oily, and volatile parts
on being penetrated by the lapidific fluid, would arrest the stony
particles ; and thereby so secure their arrangement, that the sub-
stance thus produced should exactly represent the form a nils .rue-

296

ture of wood. That the mere earthy particles of a vegetable should
thus abide together, and continue in their original form, after being
deprived of those particles, by which they had been held together ;
and that they should, even after the total removal of these con-
necting particles, instead of becoming displaced themselves, stem
the percolating particles of earth, and be able so to retain them,
that they should, combined, faithfully represent, as many specimens
do, the original peculiarity of structure of the wood, was an opinion
fraught with so many obvious difficulties, that another mode of
explanation was soon adopted.

The next theory which was proposed, with the hope of ac-
counting for these changes, was that of a SUBSTITUTION of stony,
in the place of the organized matter, whicli was supposed by many
of those who adopted this opinion, to be intirely removed. Thus
Berthold says, petrifaction is not a metamorphosis into stone, but
a removal, by putrefaction, or precipitation, of the vegetable or
animal matter; and a substitution of stony matter, in the same
manner as happens, in metals — copper being, for instance, some-
times thus substituted in the place of iron *. M. Walch also, in
the supplementary part of Knorr's splendid work on this subject,
declares his adoption of this opinion to its fullest extent. Different
species of petrified woods, he says, teach us that all the particles,
even the finest, constituting the substance of any extraneous body,
may successively disappear, and be replaced by foreign heteroge-
neous particles, with so much regularity, that the body, which is pro-
duced from them, may possess, perfectly, the form of the original
body ; preserving all its characters, and at the same time not re-
taining any at all (autune de toutes) of its original particles f . To

* De Rebus Petrifactis, &c.— a Dan. Gothilf. Bertholdo. 1766.

t Recueil des Monumens des Catastrophes que la Globe de la Terre a essuie"s, &c.
— commence" par Mons. Wolfgang Knorr, continue par ses HeYitiers, avec 1'Histoire
Naturelle de ces Corps, par Mons. Jean Ernest Emanuel Walch, 1715, tome iii. Pref.

297

the process by which this change is accomplished, Mr. Kirwan, be-
lieving petrifaction to be thus performed, applies the term, SUB-
STITUTION; and describes it as — " the introduction of stony, and
sometimes of metallic substances, into organic bodies, whether of
the vegetable, or of the animal kingdoms, in proportion as the
particles of these organic substances are destroyed by putrefaction,
so as to assume the place, and, consequently, the form and figure,
of these, as if cast in the same mould. The mineral substances,
thus moulded, are," he says, " in the most proper sense of the
word, called PETRIFACTIONS *."

Mons. Daubenton is of opinion, that petrifaction only takes place
in those bodies, whose composition is such, that a part of them
already possesses a stony hardness. Such, he remarks, are the
crustaceous coverings of some animals, shells, bones, scales, mad-
repores, &c. In these substances, composed of a stony, and of a car-
tilaginous part, he thinks the following change may ensue, on their
being long left in a humid situation. The earthy part will separate,
and fall away from the cartilaginous part; and if the lapidific juice
meet with a body in this state, the earthy particles will enter into
, the cavities thus left in the cartilaginous part, and, by filling them,
accomplish the petrifaction in such a manner, as to give the body
the appearance of being still organized.

With respect to the apparent petrifactions of wood, fruits, &c.
he supposes them to be formed in the moulds which have been left,
by those substances, in the surrounding earth, the external surface
of these bodies retaining the exact impression of the surrounding
mould. But sometimes, he observes, we discover the marks of the
internal structure of the wood ; and to account for this, he adopts,
with Mr. Kirwan, the idea of substitution. Here, he says, the water
carries away, gradually, the ligneous fibres, and as gradually depo-

* Geological Essays, by Richard Kirwan, Esq. p. 137.
VOL. I. Q Q

298

sits, in their places, the stony particles ; which are necessarily dis-
posed in the same order, and in the same form, with those of the
ligneous parts, which have been removed ; since they have been
distributed in the same points, and have been moulded in the same
cavities, which the molecules of the decayed wood have left. All
the substance of the wood is thus, by degrees, removed, and its
place exactly filled by a stony substance, bearing the exact appear-
ance of the wood itself. These stones, then, he says, are, in fact,
not petrifactions, but only stony depositions which have received
the impressions of different parts of the wood : and he concludes,
that there is no vegetable substance which can become petrified ;
and that petrifaction can only take place in animal substances, of
which a part already possesses a stony hardness. To prevent any
mistake on this subject, he observes, that petrified wood should
possess the distinctive character of wood, by possessing the medul-
lary productions. It is not sufficient to see concentric layers, it is
necessary there should be also lines traversing these annual layers ;
as they are beheld in the tranverse section of a tree, from the pith
to the bark, and in some trees, as the cork and the green oak, even
in the bark itself*.

The opinion of Mons. Fourcroy, on this subject, very much
resembles that of Mons. Daubenton. The layers, he says, of fossil
wood, penetrated by water, lose a portion of their dissoluble, mu-
cilaginous, and extractive matter, with a part of the hydrogen,
which they contained. Hence they approach to the state of a pure
wooden skeleton : the external substance of the woody fibres being
even decomposed, and taking on the colour and appearance of
charcoal. It appears, he says, in fact, that, although still woody,
the fossil wood is approaching to destruction ; and that a still'
longer stay in the earth would destroy it entirely. With respect to

* Legora Nonnales, torn, iii, Observations sur les Petrifications,

299

petrified wood, or other vegetable matter, he remarks, it is a great
error to consider it, as a conversion of vegetable matter into silex,
as the term seems to imply. There exists, he_says, to be sure, sili-
cified fossil matters, which present to our view, not only the texture
of wood, in general, but that even of particular kinds of wood :
but the greater part of such specimens are, he thinks, merely pieces
of jasper, the fibrous appearance of which imitates that of wood.
Even in those specimens where, besides concentric layers, the me-
dullary prolongations are seen spreading from the centre to the cir-
cumference, and which is, he thinks, the only incontestible proof
of the specimen having been wood, it is not to be imagined that
the original woody substance, retaining its form, texture, and di-
mensions, is converted into silicious matter: it is necessary, he
says, to conceive otherwise of fossil bodies, bearing these marks of
organization. Wood, leaves, fruit, and all other kinds of vegetable
matter, improperly said to be petrified, have been gradually de-
stroyed, almost atom by atom, within the wet earth, where it has
left a hollow mould, which becomes exactly filled by the silicious
earth which the water has conveyed thither. Thus it really is not
a petrified wood, but only a substitution of silicious matter, mixed
with other earths and metallic oxides, in the place of the wood.
This species of silification is then, he adds, a proof of the complete
destruction of the vegetable matter, and of the disappearance of what-
ever constituted its elements*.

Innumerable objections oppose themselves to the attempt, of
accounting for the lapidification of vegetable substances, by this
process of substitution. In what manner can it be supposed that
a line, smaller than a hair, extending from the centre of a piece of
wood to its circumference, can have its original component parts
taken away, and their places so exactly filled by earthy particles,

* Syst&ne des Comioissances Chimiques, torn. viii. p. 255.

300

merely deposited from water, as to preserve its continuity unbroken ?
If this should be even imagined as possible, in the instance of a
single line — can it be admitted that such a regular abstraction and
supply, imitating exactly those processes only known to be per-
formed by organized parts, could thus take place, through every
series of the vessels, and every fibre of the decayed wood ; and
thereby produce an appearance, not in the least differing, from that
of the original wood itself. But were even this to be claimed as
possible, and were it allowed that the form of the wood might be
thus preserved, and its structure imitated ; how should we, on this
hypothesis, account for the original colour of the wood being ex-
actly retained? Can it be supposed that the original molecules
being thus removed, that the added particles of earth, derived
from the surrounding mingled mass, should be so disposed, that
the arrangement, and blending, of the variously coloured particles
should yield an exact imitation of all the different hues, and of the
disposition of the characteristic shades of colour, of the original
wood. It indeed appears to be impossible, that the almost for-
tuitous disposition of the atoms, by which such a substance would
be formed, could perfect so exact a resemblance in the figure, struc-
ture, and colour of an organized body, that the eye, unaided by
the touch, should not be able to discover the difference.

The theory of Dr. Hutton next demands examination. The im-
pregnation of silicious fossil wood, he supposes to have been effected
by injection with flint, in a state of simple fusion by fire. " With
whatever different substancrs," he says, " the woody body shall be
supposed to have been penetrated, in a state of solution by water,
the regular structure of the plant would still have remained, with its
vacuities, variously filled with the petrifying substances, separated
from the aqueous menstruum, and deposited In the vascular struc-
ture of the wood. There cannot be a doubt with regard to this pro-
position ; for, as it is, we frequently find parts of the consolidated

301

wood, with the vascular structure, perfectly in its natural state and
situation, but if it had been by aqueous solution that the. wood
had been penetrated and consolidated, all the parts of that body
would be found in the same natural shape and situation. This,
however, is far from being the case ; for while, in some parts, the
vascular structure is preserved entire, it is also evident, that, in
general, the woody structure is variously broken and dissolved by
the fusion and crystallization of the flint*/'

The first proposition which the Doctor lays down, and with regard
to which, he says, there cannot be a doubt, is that " with whatever
different substances the woody body shall be supposed to have been pene-
trated, in a state of solution by water, the regular structure of the
plant would still have remained, with its vacuities, variously filled with
the petrifying substances, separated from the aqueous menstruum, and
deposited in the vascular structure of the wood." The test which the
Doctor has here proposed for ascertaining, whether the petrifaction
of wood is, or is not, an operation dependent on aqueous solution,
is certainly the best adapted of any that could .be devised ; for, as
is implied in the Doctor's statement, if the regular structure of the
plant remain, with its vacuities, variously filled with the petrifying
substances, separated from the aqueous menstruum, and deposited
in the vascular structure of the wood ; then the change cannot have
b*een effected by any other means, but an aqueous solution of the
impregnating matter. Now not to dwell on the general evidence,
which, 1 think, is yielded by almost every specimen of silicious
wood ; I will urge the more direct evidence which is afforded
by a particular specimen I possess. In this specimen, impregnated
with silex, either by gradual decay, or by the mechanical action of
water, the fasciculi of longitudinal fibres, which appear to have
retained their natural colour, seem to have been so loosened in their
attachments, as to have hardly adhered together, previous to their

* Theory of the Earth, vol. i. p. 61.

302

impregnation ; and in some parts very considerable vacuities have
been formed. In its present state, exceedingly small silicious crys-
tals invest every fasciculus, and line every interstice and cavity, but
without proceeding so far as to entirely obliterate them, or in the
least to alter the regular structure of the wood ; all the remaining
parts of which appearing to retain their natural shape and situation.

That such an investiture of crystallization, spreading almost over
the whole surface, could have been thus regularly disposed, from
an injection of flint rendered fluid by heat, without obliterating the
small cavities, and interstices of the wood, by the introduction of the
melted matter, and without affecting the regular structure, or even
the colour of the wood, is hardly to be conceived ; whilst the
supposition of the silicious matter having been gradually applied,
from an aqueous menstruum, offers us, comparatively, no difficulties
to encounter.

In the concluding part of the Doctor's observations, two positions
are laid down ; first, that if it had been by an aqueous solution,
that the wood had been penetrated, and consolidated, all the parts
of that body would be found in the same natural shape and situa-
tion ; secondly, that the woody structure is variously broken and
dissolved by the fusion and crystallization of the flint. With respect
to the first of these positions, it certainly does appear to be unten-
able, since many specimens of fossil wood bear the strongest marks
of having suffered much from decay previous to their impregna-
tion ; and surely, from long maceration and agitation in water, the
pressure of surrounding hard bodies, and the numerous accidents
to which this wood may have been exposed, previous to its impreg-
nation, it would not be surprising, if, after its consolidation, by the
means of an aqueous menstruum, all its parts were not found in
their natural shape and situation. On the other hand, specimens
are frequent in which the natural shape and situation of the parts
are preserved throughout, even to fibres, distinguishable only by

303

the aid of glasses. Here again it may with propriety be questioned,
whether in this case, the injection of silex, melted by heat, could
possibly have taken place in this wood, without" entirely destroying
its structure, as well as colour. This breaking and dissolution, in
some parts of a specimen, the Doctor, in the second position, con-
siders as attributable to the fusion and crystallization of the flint.
How this dissolution of the parts of the wood may be accounted
for has been endeavoured to be shown above, in part; and other
causes supposed to be equal to the production of the same effect,
will be soon pointed out. In the mean time, it may be sufficient,
to point out the difficulty of supposing, the injection of the melted
flint to have occasioned the destruction of the vascular structure, in
one part of a specimen ; whilst in another part of the same speci-
men, consolidated in the same manner, the structure has suffered
little or no injury.

Professor Playfair states that, " on examination, the silicious
matter is often observed to have penetrated the wood very un-
equally, so that the vegetable structure remains ,in some places
entire ; and, in other places, is lost in an homogeneous mass of agate
or jasper. Where this happens, it may be remarked, he says, that
the line which separates these two parts is quite sharp- and -distinct;
altogether different from what must have taken place* had the flinty
matter been introduced into the body of the wood, by any fluid in
which it was dissolved ; as it would then have pervaded the whole,
if not uniformly, yet with a regular gradation*/'

Mr. Playfair here undoubtedly speaks, of specimens which he has
either himself seen, or of those, the description of which, he con-
ceives, warrants this account. My objections here must be neces-
sarily feeble, being only of a negative kind. During the perpetual
examination, for several years, of specimens of fossil wood, I can
say, that I never yet saw one in which the line separating these two-

* Illustration of the Huttonian Theory, p. 25.

304

parts of the specimen was quite sharp and distinct, and different
from what must have taken place, had the flinty matter been intro-
duced into the body of the wood, by any fluid, in which it was dis-
solved. On the contrary, in numerous specimens now before me,
in which the fibres of the fossil wood are in some parts distinct, and
in others lost, I seek in vain for any line of distinction, as to the
penetration of the wood with silicious matter ; but see, in all, no
difference whatever, in this respect, in that part where the struc-
ture is confused, or where it is distinct ; nor do I find the least rea-
son to suppose, that the silex has not pervaded the whole, in the
most uniform manner.

" In those specimens of fossil wood that are partly penetrated
by agate, and partly not penetrated at all," the Professor says,
" the same sharpness of termination may be remarked, and is an
appearance highly characteristic of the fluidity produced by fusion."
Here I have again to lament the never having had the opportunity
of seeing a specimen similar to those which are here alluded to. I
possess several specimens of agatine, opaluie, and jasperine woods,
the appearance of the external parts of which very nearly resemble
that of unchanged wood ; but examination soon shows that these
parts have also been fully penetrated by the silex. That such spe-
cimens do not exist, it is not my intention to assert ; it is quite
sufficient to remark, that such specimens would only prove that
the petrifying matter had only been applied to one particular part
of the wood ; a circumstance of which there certainly exists no
reason to prohibit the occurrence, in the case of the application of
an aqueous solution of petrifying matter.

Mr Kirwan, indeed, quotes an account, that the Emperor of
Germany, being desirous to know the length of time necessary to
complete a petrifaction, obtained leave from the Sultan to take up,
and examine, one of the timbers that had supported Trajan's bridge
over the Danube, some miles below Belg *ade Jt was found, it is

305

said, to have been converted into an agate, to the depth only of half
an inch ; the inner parts being slightly petrified, and the central
still wood *. What authority is due to this account, I pretend not
to determine : but must acknowledge, that no circumstance, which
I have arrived at the knowledge of, would have induced me to have
expected such an event. If the fact be so, it not only is an addi-
tional answer to the reasonings of Mr. Playfair, but proves, as Mr.
Kirwan observes, that silicious particles are soluble in water, are
taken up by wood, and that petrifaction is carried on, under ap-
propriate circumstances, in modern times -f.

Having sketched the outlines of those hypotheses, by which the
process of the petrifaction of vegetable matter has been endea-
voured to be explained ; and having also stated those circumstances
which induce me to hesitate, at admitting their sufficiency, I shall,
in my next, venture to offer a different explanation of this process,
and shall then proceed to examine, whether it agrees any better
with the appearances which these substances yield.

Yours, &c.

* Juste Gesch. des Erdkorpers, 267. I Gerh. Gcsch. 222.
t Geological Essays, p. 140.

VOL. I. RR

LETTER XXX.

THEORY OF THE PETRIFACTION OF WOOD PROPOSED. . ..PETRIFI EI>
WOOD, SILICIOUS, CALCAREOUS, AND ALUMINOUS.

VV HILST endeavouring to ascertain the nature of the processes,
by which the several bituminous substances have been formed, it
was suggested, that the ligneous parts of vegetables, in detached
pieces, as well as in large masses, when placed in subterranean
situations, and pervaded by moisture, pass through certain spon-
taneous changes, from the intestine motion of their particles, and
the new arrangement of their principles^ by which they gradually
acquire a bituminous nature. In this manner is formed bituminous
wood ; which, if the process is not interrupted, passes into the state
of pure bitumen; or if exposed to the influence of certain circum-
stances, already particularized, a different modification of its par-
ticles ensues ; and jet, or some of the different varieties of coal, are
produced. But if the superincumbent strata be not sufficiently
compact, to confine the more volatile matters ; if the water be in
too large, or in too small a quantity, or not sufficiently stagnant ;
or if any other circumstance prevent the farther progress of the
bituminous fermentation — the bituminous wood, being now ren-
dered unfit for the food of insects, and having acquired a consider-
able degree of durability, may remain without any farther change
for ages. This fact is rendered evident in many parts of this king-
dom, where trees have been thus preserved from a period beyond
the tradition of man.

In this bituminized wood, two circumstances are observable, which
are particularly deserving notice. The first is, that, although ren:-

30?

dered essentially different in its nature, it frequently happens, that
its form has undergone no change, and that the disposition of its
fibres has suffered hardly any alteration. The second is, that, when
found in wet situations, its substance is so thoroughly pervaded by
water, that it may be discharged from it as from a sponge.

Reflection on these circumstances must show, that this wood is
in the exact state which fits it, for becoming a similar substance,
with that which most specimens of fossil wood present to our view.
The form and structure of the wood are curiously preserved ; water
pervades every part of it ; and its durability is such, as to ensure
its preservation until that event happens, on which its consolidation
appears to depend — the saturation of the water, with which it is in
every part imbued, with earthy particles, in a state of solution.
These consolidating, by the formation of extremely minute crystal-
lizations, through the whole softened mass of bituminized wood,
give it a calcareous, or a silicious substance, without disturbing
the existing arrangement of its fibres. Thus appear to be formed
all those fossils, which really deserve the name of vegetable petri-
factions ; and thus, perhaps, can, alone, be explained that curious
phenomenon — the exact preservation of even the minute fibres of
the wood ; still retaining their continuity, and their original charac-
teristic disposition, whilst their substance has undergone a conver-
sion into stone.

Thus, 1 trust, may the petrifaction of, by far the greater part of,
vegetable fossils be explained. The several species, and varieties,
dependent, on the different substances which have been thus
changed, on the kind of earth, and on the state in which the par-
ticles of earth have been deposited, will necessarily be the subjects
of separate examinations. For although, in almost every case, of
vegetable petrifaction, the earthy particles appear to have been de-
posited chiefly in a crystalline form, it is not meant to deny, that
this process may have been aided by the introduction, and deposi-

308

tion, of those fine earthy particles, which have been merely sus-
pended in the water. On the contrary, in, by far, the greater
number of instances of vegetable petrifactions, the combination of
both operations is discoverable.

In thus endeavouring to account for the formation of most of
the endless variety of vegetable petrifactions; which, from the
wonderful appearances they display, and the circumstances under
which they are found, are considered as, almost, anomalies in nature,
I am aware, that the theory proposed, respecting the formation of
bitumens, will be exposed to a severe test : tried by such a touch-
stone, the degree of estimation to which it is entitled, can hardly
fail of being determined.

Although convinced of almost the universal agency of bitumini-
zation, on such vegetable substances as have been rendered sub-
jects of the mineral kingdom, yet it does not appear to be the
sole process, by which vegetable matters may be preserved from
total decay, a sufficient length of time, to admit of their slow
impregnation with lapideous or metallic substances. The ligneous
substance we have already seen, is of so indestructible a nature, as
to secure its long continuance, in various situations without under-
going any material change of appearance ; even after the other con-
stituent parts of the wood have been removed. This appears to be
the state in which light rotten wood, or touch- wood, exists : all the
constituent parts, excepting the ligneous substance, having been
removed, either by the long continued action of the air, or by some
morbid action of the vessels of the wood. If this species of wood,
therefore, be placed in situations, in which water holding earth in
solution can permeate it, there exists but little doubt that it may
become petrified. Another mode 03' which the mineralization of
vegetables may be secured, appears to be, that of decaying, but
comparatively, recent vegetables, becoming impregnated by some
saline, metallic solution, of iron, for instance, whilst a precipitated

309

oxide of the metal fill up the interstices, and involves the whole
in a confused mass, as may be seen in the bog-iron of Shropshire,
and many other parts.

But, even admitting these instances of variation, I trust you will
perceive that the grand agent in the mineralization of vegetables,
is the process of bituminization ; which readily melts down the lig-
neous substance — that substance which yields to hardly any other
process, natural or artificial, and which resists almost every power,
but that of fire. The examination of the vast variety which vege-
table fossils yield, and the attempt to explain the circumstances,
on which their different appearances depend, will best serve to show
the degree of solidity possessed by this theory, which thus sup-
poses the process of bituminization, to be the basis, as it were, of
the petrifactive process by which the greater part of vegetable fos-
sils have been formed.

The earths which are most frequently found to be the chief con-
^stituents of vegetable fossils are silex, lime, and alumine ; and, ac-
cording to the preponderance of eitheir of these earths, may the fossil
be distinguished by the term silicious, calcareous, or aluminous.
Unwilling to take liberties with the mode of expression which com-
mon usage has authorized, unless able to demonstrate a positive su-
periority, in the mode which is proposed to supersede that which is
already adopted, I will not urge the adoption of such expressions,
as pyritified wood, silicitied wood, &c. which point out the circum-
stance, 'of the substance having been once wood, but having now
assumed an entirely different nature. ' I cannot, however, omit to
observe here, that such words as do imply a real transmutation,
may frequently be employed, without meriting that degree of cen-
sure, which we have already seen is bestowed on themv by M.
Daubenton ; since, although the stony nature of such substances is
admitted to be merely the result of an earthy impregnation, the
substances thus impregnated will, I believe, in general, be found to

310

have suffered an actual transmutation — a total change in its nature ;
that which was ligneous having at least become bituminous.

As the fossil wood, which appears to exist most abundantly is
that which has undergone a silicious impregnation, and as the for-
mation of this species of fossil wood appears to be the most diffi-
cult to be explained, we will take it first' into consideration. But
as its impregnation is here assumed to have been accomplished by
a solution of the silex, in some aqueous menstruum ; a circumstance
of which no positive proof can, perhaps, be adduced ; it is neces-
sary, previous to entering into a particular examination of this
substance itself, to determine what degree of force is possessed,
by that collateral evidence, to which we are necessitated to have
recourse.

So regularly does the earthy matter appear to have been diffused,
through every part of the changed wood ; and so intimate is the
union which has taken place, that its deposition from a solution
appears to be obvious. That it has chiefly been deposited in minute
crystallizations, which, by their regular apposition to each other,
have formed that continued silicious substance, of which these fossils
are composed, may be inferred from the circumstance of most of
these specimens having their surface invested with a crust of ex-
tremely minute crystals ; and from a similar investiture, even, sur-
rounding, in some specimens, every distinct compages of fibres, and
lining the sides of every cavity, without obliterating them ; whilst,
in other specimens, similar cavities, and fissures, proceeding from
a deficiency of wood, or biturhinous matter, are filled with a trans-
parent quartzous mass. These circumstances are so plainly indica-
tive of a slow deposition, from a solution in some aqueous men-
struum, that here we might have rested our proof; if it had not
been asserted, that all these effects might have been produced by
the injection of silex, rendered fluid, by simple fusion, by heat. This
renders it, therefore, necessary, that we should first endeavour to

311

ascertain, whether corresponding impregnations of other substances
with silex, are attributable to the influence of water, or of fire.

Yours, &c.

LETTER XXXI.

SILICIOUS PEBBLES. ...CONJECTURES AS TO THE TIME, AND MODE
OF THEIR FORMATION. ...CRYSTALLINE FLUID OF REAUMUR....
AGATINE NODULES. ...THEORY OF THEIR FORM ATION.... OPI-
NIONS OF DR. HUTTON AND MR. PLAYFAIR.-.. AQUEOUS ORIGIN
SUPPORTED.

1 HERE is hardly any one of the combinations into which silex
enters, but displays some wonderful phenomenon. The sand and
pebbles which we tread upon, and which so seldom attract the
attentipn, are fraught with mystery. Henckel, with mingled per-
plexity, and wonder, exclaimed, " O Caillou ! Caillou ! qui est ce
qui t'a engendu ? Est ce done qu'il ne seroit possible de se faire
quelque idee de la maniere que cette formation se fait ?." ,

Almost without a hope of adding to what is already known,
respecting these substances, I shall lay before you a few thoughts
on the formation of silicious pebbles ; hoping, that I shall thereby
at least, make some advancement in a knowledge of the circum-
stances, on which the silicious impregnations of wood depend.

Various opinions have been entertained as to the aera of the for-
mation of pebbles: some believing their existence to be coeval

312

with the creation; others supposing them to have obtained their
present forms at the reformation of the world, after the deluge ;
whilst others conjecture, that their formation is going on at the pre-
sent day. That many of them have been formed, at periods later
than the creation of the world, is rendered indisputable, by the
various impressions of organized substances which they bear. The
strongest evidence which has been adduced as to their more recent
formation, is that of Dr. G. Gardner, of Aberdeen, contained in a
paper published in the Philosophical Transactions* ; he relates,
that, " upon the river Don, a little below the bridge, upon the
river's mouth, there is a bank, the face of which is broken down ;
and it is full of stones, which one would think were in fieri ; they
are all either round or oval, of different sizes ; the faces of most of
them are broken off, they are soft, and will easily rub down with
your hand ; they are of different grits and colours, and are made
up of different sands and clays mingled together ; the clay is soft,
both to the hand and taste ; in some of them, white, in others, grey,
though, in some places, the clay and sand are hardened to a very
considerable degree/' Dr. Gardner proceeds to remark, that they
bore a very near resemblance to such oval stones, as we see in the
fields ; and that where they were softest, the bed which each stone
laid in, was always hard, and of another grit and colour. It is
however by no means improbable, that the pebbles here described
might be in a state of decomposition. The pebbles of which the
pudding-stone is chiefly formed, generally yield such an appearance,
as may be supposed to have been the effect of pressure, whilst they
existed in a soft state ; and we have a curious instance, related by
the celebrated Bergman, illustrative of this circumstance — a moun-
tain of pudding-stone, in the lower strata of which, the pebbles
shewed evident marks of having suffered compression; being re-

* Philosophical Transactions, Vol. XV. N» 175.

313

duced to little more than the thickness of half-a-crown. Little
margaceous nodules, the mineral bezoars of some, composed of
various lamina? of soft earth, of different colours, may be frequently
found in the gravel-pits in England, and in large heaps in several
parts of Italy ; appearing to differ from silicious pebbles, only in
not having been impregnated with silicious matter. That such an
aggregation of particles of clay and sand, as may form a fit sub-
stratum of pebbles, may even now take place, and that these bodies
may attain the forms of pebbles by attrition and the action of water,
is very probable. In what manner that process, on which their
induration depends, is accomplished, is not, however, easy to ascer-
tain.

The opinion of Mons. Reaumur, as to the manner in which this
part of the operation, in the formation of pebbles, is accomplished,
appears to be not only perfectly consonant with the appearances
which pebbles yield ; but also with those which are yielded by the
several silicious petrifactions, which are more particularly the ob-
ject of our inquiry *. He remarks, that, by a coarse operation, emery
is reduced to powder, and suspended in water, for several days ;
but, he observes, Nature may go much further ; for the particles
which water detaches from hard stones, by simple attrition, are of
an almost inconceivable degree of fineness. Water, thus impreg-
nated, he supposes, contributes to the formation of pebbles, by
petrifying of stone, as it were a second time : stones, already formed
but remaining of a spongy nature, acquiring a flinty hardness by
an impregnation with this crystalline fluid. Thus impregnated,
masses of different clays, chalks, marles, and boles, become flinty
stones ; and thus, he remarks, this crystalline fluid, filtering through
a porous lime-stone, will deposit its very minute particles, in all
the interstices, existing between the particles of the stone, which

* Memoires de 1* Academic des Sciences, &c. 1721, p. 241.
VOL. I. S S

314

at last they will quite close up. All the spaces between its mole-
cules being thus filled with silicious matter, which serves to ag-
glutinate the molecules in a compact mass, the stone, he concludes,
will possess a flinty hardness; and will exhibit nothing of a gra-
nular appearance in its fracture.

From such an impregnation of masses of various earthy matters
proceed Egyptian pebble, various-coloured jaspers, agates, &c. and
by such an introduction of silicious matter, in aqueous solution, or
in a state of extreme division, into moderately soft, and rounded
nodules, of different combinations of the earths, variously coloured
by metallic oxides, and chiefly by those of iron, are formed those
pebbles, whose external coat, differing from their internal sub-
stance, distinguish them from the small boulders of porphyry,
jasper, agate, cornelian, marble, lime-stone, £c. which, detached
from the rocks, and forcibly agitated by the waters of the sea, be-
come rounded by attrition against each other.

In the present advanced state of chemistry, it is unnecessary to
dwell on the opinion which has been entertained by M. Patrin,
M. de Carosi, and others, that chalk undergoes a conversion into
flint, except for the sake of remarking, that all those apparent
transmutations, which have given rise to this opinion, are easily
explained, by supposing a partial introduction of a silicious fluid,
in various quantities, into porous calcareous earth.

The numerous impressions of organic substances, such as shells,
coralloids, spines of echini, &c. discoverable in the substance, and
on the surface, of pebbles, prove these to have existed in a soft
state ; and render it probable, that these bodies became involved
ia them whilst the pebbles were yet forming among the exuviae of
marine animals at the bottom of the water. By the concentric line
observable in many pebbles, the accumulation of successive coats,
whilst in a soft state, is sufficiently proved ; and the various plum-
pudding stones clearly point out the infiltration of a silicious

315

fluid, which has perfectly cemented together the several pebbles,
which had before been connected, by interposed particles of sand,
clay, &c.

Frequently the external surface, or coat, of the pebble, will be
formed by a hard silicious crust ; a small part of which being re-
moved, shows that the remaining substance of the pebble is a soft,
pulverulent, sometimes argillaceous, and sometimes calcareous,
matter. In this instance it appears that the silicious matter has
introduced itself only to a certain depth in the substance of the
pebble ; the rapidity of concretion, or crystallization, having pre-
vented any subsequent introduction of the fluid. A pebble, now
before me, seems plainly to show, that the process, by which the
induration of these pebbles is accomplished, is not suddenly per-
formed. A part of this pebble is covered with a crust similar to
that with which these pebbles are commonly invested, which termi-
nates by a strong defined ridge, within which is a substance, the
appearance of which marks it to have been the soft internal
substance, which had been deprived of its crust, previous to the
thorough penetration of the silicious matter. In this are stuck
about twelve small black silicious fragments, which, by a subse-
quent infiltration of silicious liquor, are now firmly connected in
one solid mass, with the original soft internal substance of the
pebble, a depression existing in one part, formed by one of these
fragments, which has since separated.

Organic remains, which originally contained a considerable pro-
portion of calcareous earth, are frequently found imbedded, or en-
veloped, in these pebbles ; and are often so thoroughly pervaded,
in some parts, by the silicious impregnation, as to be absolutely
silicious ; but sometimes, the calcareous earth is, in other parts of
the same stone, still so predominant, and is united with so much
carbonic acid, as to effervesce strongly on the application of even
vinegar. Strong evidence of the slow accretion, and of the long-

continued application of the indurating matter, in a state of solution,
to these pebbles, during, and even subsequent, to their having as-
sumed the general form which they now possess, may be found in
a variety of the silicious pebble, which appears to have derived its
shape from an organic body, apparently a species of coral, which
it has invested. In this pebble, the holes are fequently left,
through which some parts of the contained body have projected ;
but frequently it will also be found, that these holes are filled up,
in various degrees, by silicious matter, showing the strongest marks
of its deposition, from an aqueous solution, subsequent to the for-
mation of tjie stone ; sometimes it surrounds and penetrates the ex-
traneous body itself, and at other times fills Up the hole, so exactly
as to leave externally only a circular seam ; not much differing from
the appearance of a cicatrix. Another proof of the subsequent
addition of silicious matter, in solution, to pebbles, offers itself in
the junction of the fractured parts of the boulders of sand-stones,
for instance, by the interposition of silicious matter ; thus, fre-
quently, will the fragments be seen to be united by a very minute
seam ; not such as might be supposed to have originally existed in
the rock of which this stone is a boulder ; but a slight crack pass-
ing through its substance, and which yields to different degrees of
force in different pebbles, according to the various degrees of ag-
glutination it has experienced. Haying laid before you some of
the circumstances which the pebbles, forming the vast beds of
gravel so frequent in this island, offer in proof of the influence of
water in the process of silicious impregnation, it becomes neces-
sary, in the next place, to determine, whether agates, and agatine
nodules, derive their formation from the influence of the same
agent; since it has been eagerly contended, by Dr. Hutton and
Mr. Playfair, that their formation depends on the injection, in a
state of fusion by heat, and subsequent cooling, of silicious matter.
This examination is rendered the more necessary, by the latter gen-

317

tleman's considering it to be impossible, that the igneous origin of
fossils could be recorded in plainer language, than by the pheno-
menon displayed in the formation of the agate. Concluding, as
every appearance, indeed, warrants, that the progress of consoli-
dation, both in the solid and hollow agates, has been from the cir-
cumference inwards, he says, " Now it must be considered that
these coats are highly consolidated ; that they are of very pure sili-
cious matter, and are utterly impervious to every substance which
we know of, except light and heat. It is plain, therefore, that
whatever, at any time, during the progress of consolidation, was
contained within the coats already formed, must have remained
there as long as the agate was entire, without the least probability
of escape. But nothing is found within the coats of the agate,
save its own substance ; therefore no extraneous substance, that is
to say no solvent, was ever included within them. The fluidity of
the agate was therefore simple, and unassisted by any menstruum.
In this argument, nothing appears to me wanting, that is necessary
to the perfection of a physical, I had almost said of a mathematical
demonstration *".

To determine the degree of force with which this argument op-
Poses the opinion, that these, and similar bodies, have originated
from a solution of silex, in an aqueous menstruum, will, I trust, be
best done, by endeavouring to point out those which appear to be
the most probable modes, in which these bodies may have been
formed.

Silicious and agatine nodules are formed by a solid silicious mass,
or the silicious matter is confined to a crust, varying in its thickness.
This latter kind is termed a geode, and is either hollow and empty,
or contains substances different from the crust itself, such as sand,
indurated clay, and even water. If a loose hard stone is contained

* Illustrations of the Huttonian Theory, p. 79.

318

within a stone thus formed of a silickms crust, it is the stone
named by the ancients JEtties, from its being supposed to be fre-
quently found in the nests of eagles; the contained stone being
termed the callimus. If the crust is empty, or contains loose sand,
or other earthy substances, pr is filled by any other kind of earth, it
is termed simply a geode : but it it contains water, it is then dis-
tinguished by the name enhydros.

It cannot have escaped your observation, that the absence of
water from the interior of these silicious nodules is a circumstance,
on which Mr. Playfair chiefly founds his hypothesis ; but the fact
really is, that water is very frequently found in these nodules; and
that the stone, thus termed enhydros, is very frequently mentioned
by lithologists. The German mineralogists speak of them in such
a manner, as by no means to imply their being of rare occurrence.
In Germany, indeed, from the abundance in which silicious and
agatine nodules there exist, they might be expected to be met with :
but even in our own country they are also frequently seen. They
are found, I am informed, in and about the neighbourhood of St.
Vincent's rock, near Bristol ; and in no crystalline geode, which I
have seen from St. Vincent's rock, is there a single circumstance to
lead to a doubt as to their having contained an aqueous fluid. Dr.
Plott, in his History of Staffordshire, relates, that among the best
sort of iron stones, called mush, are frequently found round, or oval,
blackish and reddish stones, sometimes as big as the crown of one's
hat, hollow, and like a honeycomb within, and holding a pint of
sweet liquor ; which, according to the colour of the comb within
(whatever the stone be without) is either red or white ; and whether
the one, or the other, of a sweet sharp taste, very cold and cutting,
yet greedily drank by the workmen. It is especially found in that
sort of mine, the country people call the white mine, which yields
the best iron-stone, where the workmen commonly, upon breaking
a stone, find it enclosed in the centre, sometimes to the quantity

319

of a hogshead, in one cavity, of a sweetish taste, but accompanied
with a vitriolic, or iron-like twang*.

Dr. Woodward, speaking of some specimens of enhydri, says-f,
" they were found, amongst many others, in sinking the wells in
Caen-Wood, whence that water, which we call the Hampstead water,
is derived. — I was down only in one of the wells, which they were
then in digging ; but I saw several of these enhydri, with a pretty
many pyrites, amongst the earth that was flung forth .of the other
wells. They are of several sizes, from the bigness of a walnut, to
about two feet in breadth. They are generally of a compressed
shape ; and lessen, or grow thinner, towards the edge, or ambitus,
of them. Those that I saw, lay about fifteen or sixteen feet deep,
in a stratum of sandy clay. The surfaces of that stratum, and the
flats or larger plains of the enhydri, lay parallel and level: they
were all hollow, and usually divided into several cells ; but these
were uncertain, in their number, figure, and capacity. The parti-
tions of the cells were rarely very thick. The outer coat was in
some double, in others triple, and in a few quadruple; as consist-
ing of two, three, or four strong crusts, involving and carrying one
another. The cavities or cells were generally near full of an insipid
coagulum, or liquor, about the consistence of cream, though in
here and there one, it was a little thicker. Twas most commonly
of a greyish colour ; but in some few 'twas of a bluish, and in
others of a blackish hue."

Whether it be believed, that these several bodies owe their exist-
ence to fire or water, it will, I conceive, be equally admitted, that
they have been formed in cavities, previously existing in the matrix,
in which they are contained. I suppose, then, that one of these
cavities becomes filled, by some small aperture, with a liquid hold-

* The N tural History of Staffordshire, by Robt. Plott, LL. D. 1686.

t ATI Attempt towards a Natural History of the Fossils of England, by J. Woodward, M. D.

ing silex in solution ; that silicious crystals form all round the ca-
vity, except at the aperture, where there is nothing to attach them-
selves to ; and that an aperture in some other part allows a regular
escape of the fluid, by which a correspondent supply is demanded
from the first-mentioned aperture, until, after, perhaps, the lapse
of ages, the crystals fill up, from the bottom and sides, to the aper-
ture by which the fluid was admitted, and form a solid crystallized
mass, from which the water is excluded. Nor does it even appear
necessary for the formation of a solid crystalline mass, that there
should be more than one opening, that which admits the fluid into
the cavity ; since the calibre of the opening bearing a proper pro-
portion to the cavity to be filled, it will remain open until the mass
of crystallization is completed ; it being reasonable to suppose,
that the fluid containing the silex would, in consequence of its su-
perior gravity, be continually supplying the place of that, which,
having been deprived of its silex by crystallization, would of course
tend upwards ; and thus might the cavity become entirely filled by
crystallization, to the total exclusion of the solvent. The sections
of agatine nodules indeed show complete and uninterrupted con-
centric coats, without any such departure from the circular form
as would point out the opening by which the cavity had been filled ;
but then it is to be considered, that it is only in one particular
direction, that this could be shown, in a section ; in every other
direction, the concentric coats will appear perfect and regular. But
when the laws on which crystallization depends are considered —
it being a process in which the suspended molecules are united to-
gether, by their particular attractive forces, according to certain
laws regulating their aggregation, and directing the forms which
they assume, to the exclusion of water, except so much as enters
into chemical union in their crystals — surely it is not contrary to
reason to suppose, that a cavity may thus be filled by crystallization,
to the total exclusion of the solvent. Thus, then, I conceive, solid

321

agatine and other silicious nodules may have been formed, to the en-
tire exclusion of the solvent.

But this assumed process being even allowed, it must be ad-
mitted, that the following variations of it must be liable to occur.
The aperture, by which the cavity is supplied, may be closed by the
crystals at its sides meeting, previously to the filling of the cavity
by crystallizations : or, instead of the liquid being admitted by one
aperture, it may percolate through numerous small openings into
the cavity. It is therefore necessary to see how the process will be
affected by these variations.

The aperture may become closed, under two circumstances : there
may, or there may not, exist some small fissures, or pores, by which
the fluid remaining in the cavity, after the supply has failed, may
drain off. If the former be the case, the hollow, empty, crystalline
nodule remains ; and if the latter, the water is inclosed, and the
enhydros, so often mentioned by lithologists, is formed.

It now remains to inquire, what would be the consequence of
the fluid infiltrating, through the substance forming the top and
sides of the cavity, instead of entering by one aperture only. Here,
as in the other instances, condensation would commence at the cir-
cumference, or sides of the cavity ; but would go on so slowly, as
to admit the further infiltration of the fluid, tor a considerable time ;
and the same porosity of the substance forming the bottom of the
mass, would likewise allow the gradual exit of the superfluous fluid.
The process which is thus carried on, in this small cavity, will be
found to agree, almost in every respect, with that, which we shall
soon see has taken place, in caverns adorned with calcareous
stalactites. As in those, so the surrounding substance in these
smaller cavities differs, in closeness of texture, in different parts;
opposing more resistance to the infiltration of the fluid, in some
parts than in others : hence the fluid oozes in a partial and irregular
manner, according to the resistance it meets with. In some parts,

VOL. I. T T

322

where the adherence of the particles is loosest, the fluid, loaded
with suspended earthy particles, slowly collects, drop after drop,
and deposits its earthy matter in a stalactitic form; whilst, from
those parts, where the resistance to the admission of the fluid is
greater, the more closely filtrated fluid deposits only a coat of drusy
crystals. The examination of a polished section of one of these
crystalline geodes shows the opaque crust, in the closest continuity
with the transparent silicious mass ; the crust being more opaque,
as it extends to the circumference, and the internal crystals ac-
quiring a greater degree of pellucidness, as they reach towards the
centre. A similar gradual departure from opacity to clearness,
effected much in the same manner, may be observed in the familiar
instance of the crystallized mass, which sometimes forms on the
external surface of a flannel strainer, which has been employed for
the filtration of a saturated saline solution. This circumstance is
particularly observable in the fossil fruits of Mount Carmel, of
which we shall have again to speak more fully ; the external sub-
stance of these is generally of a light fawn colour, marked in some
parts by a dark ochrous tinge ; but the more internal part is white,
and is generally completely transparent toward the centre. These
bodies also, almost always, contain the above described internal
stalactiform projections, which are covered by a drusy crystalliza-
tion. In these crystalline, as well as in the other geodes, water is
frequently found, forming another species of the enhydros ; and
where it has not been found, very minute, and almost impercep-
tible, fissures or pores, may, during a long space of time, have
allowed the liquid gradually to escape. A careful examination of
these crystalline and agatine nodules, and long reflection on the
circumstances, of their formation, oblige me, in opposition to the
opinions of Dr. Hutton, and of Mr. Playfair, to believe, that they
must have derived their origin, from silicious matter in a, crystal-
line form, deposited from its solution, in a fluid menstruum, filtrat-

323

ing into cavities, previously existing in the bed, in which these
bodies have been formed.

Whilst endeavouring to trace the operations of nature in these
processes, imagination, it must be acknowledged, has sometimes
prompted the judgment; but for this, I trust, I shall obtain an ex-
cuse from you, as well as from Mr. Playfair. In inquiries, respect-
ing operations performed in very distant ages, and where the ma-
terials from which- our information is to be derived, are really so
few, and so unconnected ; being snatched, either from the wrecks of
a deluge, or' the ashes of a conflagration, conjecture must, if ever,
be allowed to lend its aid, in the inquiries of science.

Yours, &c.

LETTER XXXII.

SILICIOUS WATERS OF CARLSBAD. ...OF ICELAND. ...OF BATH.*..
SILICIOUS TUFA OF THE G EYSER.... VEGETABLE CALCULI....
FLINT IN THE EPIDERMIS OF PLANTS.

SEEING reason to conclude, from this circumstantial evidence,
that the silicious matter deposited in secondary fossils, as well as
in pebbles, &c. has been held in solution, in some aqueous men-
struum, it next becomes necessary to inquire, by what solvent this
solution has been accomplished.

Subsequent observations have shown, that the opinion of Mr,
Reaumur, in favour of the agency of a silicious fluid, is established
on a much firmer foundation, than was for a long time supposed.
The celebrated Bergman first determined the solubility of silex in
simple water; ancl demonstrated its existence, in a state of solu-
tion, in the Geyser, and other boiling springs of Iceland. Mr.
Klaproth, in the year 1789> first ascertained the existence of sili-
cious earth in the boiling mineral waters of Carlsbad, in Bohemia ;
his experiments proving, that in 1000 cubic inches of the main
spring, 25 grains of silex were contained, in a state of actual solu-
tion. The quantity of silex contained in the water of the Geyser,
is even in a much larger proportion, than that which is found in the
waters at Carlsbad. Mr. Klaproth found, on subjecting the water
of the boiling spring at Rykum, in Iceland, to his analysis, that a
hundred cubic inches of it contained,

Gr.

Carbonate of soda . . . . 3
Sulphate of soda .... 5

Muriate of soda 8.50

Silicious earth 9

25.50
Being the powder left after evaporation.

Dr. Gibbes has discovered*, that 10 pints and a half of the Bath
waters contain about 20 grains of silex, being in the proportion of
about 15 grains and a quarter to the gallon. This discovery of
silex, where it was not expected, is shown, by Dr. Saunders, in his
excellent Treatise on Mineral Waters, to be of great importance, in
explaining some apparent errors in former calculations respecting
these waters.

* Nicholson's Journal, vol. iii. p. 403.

325

Bergman had at the first, accounted for the presence of silex, in
a state of solution, in such waters, to the natural solvent power of
simple water, aided by heat ; and this he thought, was alone suf-
ficient to account for this effect. Dr. Black, who made an analysis
of the waters at Rykum, which very nearly agreed with that of
Mr. Klaproth, thought that the alkali was the efficient cause of
this solution of silex in water, and that the heat was merely the
means of promoting it. But the quantity of pure soda con-
tained in these waters is so small, when compared to that of the
silex, as could not be sufficient to maintain the solution of the
latter. To obviate this difficulty, Dr. Black suggested, that the
silex had originally been united with a much larger portion of alkali ;
and that, after this solution had been completed, part of the alkali
might have become neutralized by acids, which had entered into
combination with the fluid. But, to effect the solution of the silex
by the means of the alkali, the alkali should exist in a pure, or
caustic state, of which not the least proof has been adduced ; be-
sides, as it is now rendered evident, that water alone possesses the
power of dissolving silex, it is entirely unnecessary to seek for the
aid of an alkali. The great degree of heat of these waters may,
however, be considered as promoting their solvent powers ; since,
according to the relation given by Uno Von Troil, in his account
of the Icelandic springs, the waters of the Geyser, thrown by this
immense jet of 19 feet in diameter, to the height of 90 feet, are
still found, when they fall to the ground, perfectly boiling hot.
As part of the heat must have been lost during the spouting, con-
sequently the water must have been some degrees hotter, in the
subterranean reservoirs. Thus, Mr. Klaproth observes, Nature here
affords us an instance, in the large way, of what Art performs in the
small, by Papin's digester; namely, of confined water, even while
in its unelastic, dense, liquid state, acquiring a degree of heat,
surpassing that of its boiling point. But, notwithstanding he ad-

326

/

mits the power in heat, of promoting the solution ; yet he remarks,
that experience has shown, that an actual solution of silex in sim-
ple water takes place, not only in springs, the natural temperature
of which is much inferior to the ebullient heat of those in Iceland,
but also in several other mineral waters : and even that some com-
mon sweet-water springs contain dissolved silicious earth.

In corroboration of the opinion, that the induration of various
substances may have been derived from the deposition of silicious
matter, from its solution in water, I must call your attention to the
silicious tufa which is deposited by the Icelandic hot-springs ; in
the same manner as the calcareous tufa is deposited by mineral
springs impregnated with lime, as in those of Matlock. A bason
of 60 feet in diameter, the outer border of which is 9 feet above
the opening of the pipe, as well as the pipe itself, which is 19 feet
in diameter, and which, from its depth being unknown, is consi-
dered by the Icelanders as the gate of hell, are entirely formed by
deposition from the boiling water of the Geyser, which is sometimes
thrown out, from this enormous opening, to above the height of 100
feet. This tufa having been analysed by Mr. Klaproth, was found
to consist of.

Gr.

Silex 98

Alumine 1.50

Oxide of iron . . 0 .50

100*

M. Gensanne relates, that in the mines of Cramaillot, in Tranche
Gompte, stalactitic concretions of silex form on the vaults of the
works, from the transuding water ; and that they are sometimes
found on the timbers of the mine +.

* Analytical Essays, p. 408.

f Histoire de Languedoc, torn. ii. p, 28.

In addition to the proofs, already adduced, of the solubility of
silex in water, we may notice the circumstance of its having been
found, in the proportion of 14 grains to 20 ounces, of the water
collected in the cavities of basaltic columns. Its having circulated
in the vessels of the animal body, and having been separated by
the vessels of secretory organs ; and thus forming, though rarely, a
part of the human urinary calculus, may also be regarded as evi-
dence of some weight. But its presence in different plants affords
still more powerful proof of its solubility, since we cannot conceive
its absorption, its transportation through the substance, and, lastly,
its deposition in certain parts of plants, but in a state of actual
solution in the* water, with which the plant is nourished. Its pre-
sence in the ashes of plants is well known. Rumphius relates *,
that in the island of Celebes, near Macassar, stones are frequently
found, naturally formed in the wood, and fruits of different trees:
and that they are worn by the natives, being supposed by them
to possess extraordinary powers; particularly that of defending
them from the injuries of any weapon. These, however, will not,
alone, afford us any considerable support ; since, although the
learned author describes them as flint-like stones, he mentions that
they do not give sparks, and that they effervesce on being placed
in an acid liquor. Mr. Macie has, however, found a pebble in the
joint of a Bamboo cane, which was so hard as to allow it to cut
glassf . Mr. Davy has ascertained, most clearly, that flint enters
into the composition of the epidermis of bonnet-cane, and indeed,
of all cane of this kind. He found that when pieces of this kind
of cane were rubbed together, strong sparks of white light were
produced ; and that, when forcibly struck together, the sparks were
as vivid as those from a gun-lock. The cause of this was ascer-
tained beyond all doubt, by his finding that 22 grains of the epi-

* D'Amboinsche Rariteit-Kamer. Ill Bock. LXVIII Hoofsdeel.
t Philosophical Transactions, 1791, p. 385

328

dermis of the cane yielded 9 grains of silex. He also found it in
English reeds and grasses, and in oats, wheat, barley, &c. in a suffi-
cient quantity to yield glass with the blow-pipe ; a* straw being thus
converted into a fine globule of glass : the epidermis of the equisetum
hyemale, or Dutch rush, appearing to consist almost entirely of
silex *.

Presuming, therefore, that the silicious induration of various
substances will be allowed to have proceeded from a deposition of
silex, from its solution in water, I shall, in my next, proceed to
apply this principle, whilst endeavouring to account for the forma-
tion of silicized wood.

Yours, &c.

LETTER XXXIII.

PETRIFIED WOOD. ...DIVIDED INTO SILICIOUS, CALCAREOUS, ALU-
MINOUS, &C SILICIOUS DIVIDED INTO SILICIZED WOOD AND

SILICIZED BITUMINOUS WOOD. ...THE LATTER, INTO CALCEDO-
NIC, AGATINE, JASPERINE, AND OPALINE.

-T OR those substances which bear the nfarks of having originally
existed as wood, but which now possess a' stony hardness, from the
introduction of different earthy matters, it seems proper to retain

* Nicholson's Journal, May, 1799.

329

the term, which long usage sanctions, of PETRIFIED WOOD, LITHOXY-
LOX of oryctologists. This may be divided into different classes,
according to the predominance of the different earths with which it
is impregnated : thus petrified wood may be subdivided into sili-
cious wood, calcareous wood, aluminous wood, &c.

The nature of these several fossil woods we shall now proceed
to examine, pointing out the different kinds into which each may
be again subdivided, and the several species and varieties which
demand particular observation. Fossil wood, which has been mine-
ralized by an impregnation with silex, HOLZSTEIN of the Germans,
and which we may term SILICIOUS FOSSIL WOOD, may be divided
into two kinds. The first is that, in which the wood had suffered
no real change in its nature, during its existence in a subterranean
situation, previous to that produced by the silicious impregnation.
The second is that, in which bituminization had wrought its peculiar
change on the wood, previous to its impregnation with silicious
matter. Of the former kind 1 know but one instance,, and that of
rather rare occurrence : which is, where the wood, previous to
having been buried, had undergone that change, which we fre-
quently see take place ; every part of the wood having been re-
moved but the mere ligneous fibre ; the light mass which is left
being in that state which is designated by the term rotten-wood.
The wood having been impregnated, whilst in this state, with silex,
yields an appearance exactly resembling that of rotten-wood ;
but occasions no small surprise to any one who, taking such a spe-
cimen in his hand, expecting from its appearance to find it ex-
ceedingly liglit, discovers it to be possessed of considerable weight,
from the great quantity of silex it contains. The specimen figured
at Plate II. Fig. 1. is of this kind, it having the peculiar light ap-
peara'ue of rottenwooJ, whilst its impregnation with silexhas
been to such a degree, as to have allowed it at one end to have
assumed a very high polish, from the lapidary's wheel. Since this

VOL. i. u u

330

specimen has been engraved, I have obtained other specimens of
this fossil wood, in which the loose and shivery texture of rotten-
wood is still more decidedly manifest. This kind of fossil wood
appears to be that to which the term of SILICIOUS WOOD may be
most appropriately applied. The second kind of silicious fossil
wotod is that which, previous to its impregnation with silex, had
undergone the change which the bituminous fermentation induces ;
this kind of fossil wood may be termed SILICIZED BITUMINOUS
WOOD ; and its several species will be found to have depended
much, for their general appearance, on the degree to which the
bituminizating process had proceeded, in the wood, previous to its
lapidefaction.

Bituminous wood, we have seen, may exist in two states ; in one,
the fibres, although rendered bituminous, and perhaps softer than
in their original state, have not been so far changed as to run toge-
ther and destroy the natural separation which exists between them.
A specimen of bituminous wood in this state, dug up at BJackwall^
is represented at Plate I. Fig. 1. In the other state, the bituminous
fermentation appears to have proceeded so far, as to have occasioned
such an approach to fluidity, in the bituminized wood, as to have
allowed it to run together in a mass, by which the ligneous texture
and fibrous appearance have been lost. The Bovey-coal, of which
we have already spoken, and which has been figured in Plate I.
Fig. 3. is an example of bituminous wood, which has existed in this
state. In specimens of this wood, its state of softness, nearly ap-
proaching to fluidity, may be inferred from the fibres, in one part
of a specimen, being disposed in various distorted directions, very
different from those which naturally belong to the woody fibre,
whilst, in another part, they seem to have run together in one mass,
in which every trace of fibrous texture is obliterated.

SILICIZED BITUMINOUS WOOD may, therefore, agreeable to these
two different states, in which bituminous wood has existed, be

331

divided into those, in which the bituminized fibres, having re-
tained their solidity at the time of being impregnated with silex,
have not allowed any diffusion of the matter, of which they were
constituted, in the surrounding silicious fluid, which has merely
penetrated and involved the bituminous fibres, and filled up all the
interstices, without having been itself affected by the bitumen ;and
into those, in which the bituminous mass has been in so fluid a
state, as to have allowed its intimate mixture and union, with the
permeating lapidific fluid, which has thereby assumed, with other
peculiar properties, a lustre similar to what might be expected,
from a mixture of silex and of bitumen. The species into which
silicious woods may be divided, appear to be, 1st, CALCEDONIC
FOSSIL WOOD; 2dly, AGATIZED; 3dly, JASPERINE; and 4thly,
OPALINE FOSSIL WOOD. These several species we will now proceed
to notice, in the order here observed.

Yours, &c.

LETTER XXXIV.

CALCEDONIC WOOD...AGATINE....JASPERIZED.

fossil wood appears to be the most simple form, in
which silicized bituminous wood is found to exist ; and, therefore,
serves to show, most clearly, the nature of the impregnation of
solid bituminous wood with a solution of flint. In this wood, the

332

colour and general appearance of which manifests very plainly its
previous bituminization, the silicious impregnation, in those spe-
cimens which I possess, has been such as to have given to them suffi-
cient hardness to dispose to the conchoidal fracture, approaching
in some parts to the shivery ; and to occasion them to yield sparks,
by percussion with steel. Their external surface has sometimes the
whiteness of wood which has been long exposed to the air ; but a
section of them shows the internal substance to be of the colour of
dark brown bituminized wood. The character of this species of
fossil wood is, that although the silicious fluid has pervaded every
part of -it, it has entered into no other union with it, than that of
penetrating every fibre, and filling up every minute interstice,
without entering into such chemical union with the bitumen, as to
allow it to manifest the least trace of bitumen, in its lustre, transpa-
rency, or colour, in any of those parts where the silex has been
allowed to transude, and separate from the general mass of the im-
pregnated wood : the silicious matter assuming, generally, in those
situations, the mammillated surface, and that degree of transparency,
which is in general displayed by silicious matter, in that form which
is termed mammillated calcedony. In PL II. Fig. 10. is represented
a specimen, showing the whitened surface, beautifully invested with
transparent mammillated calcedony, appearing as if it had perco-
lated through the substance, and had hardened on the surface of
the wood. Plate VIII. Fig. 9- represents another specimen, in
which the circular cavities, which had been formed by the teredo
navalis, are filled up by the transudation of the uncoloured, pellucid
calcedony. At Plate II. Fig. 11. a specimen is depicted, which
appears to have suffered a higher degree of bituminization, in conse-
quence of which the filtered silicious matter, with which it is every
where beset, in the form of yellow semi-pellucid globules, appear to
have derived some slight tinge from the bitumen ; which, in conse-
quence of the more perfect state of bituminization, in which it had

333

existed, may be presumed to have been in a more fluid state, than
the bituminous wood which had helped to constitute the two before-
mentioned specimens. Specimens of this kind of fossil wood are, I
believe, rather rare; but the separation of silicious matter, with
which solid bituminous wood has been saturated, may be very fre-
quently seen in specimens, in which the whole silicized bituminous
substance is covered with resplendent drusy quartz crystals. In-
stances of this kind are so numerous, as to render an illustration of
this appearance, by a Figure, unnecessary.

AGATINE fossil wood. This term may be appropriated to such
fossil wood as possesses a glassy lustre, breaks with rather a con-
choidal fracture, gives sparks freely with steel, and is either marked
by spots and illinitions of a bright crystalline matter, with which its
vacuities have been filled, or has its several surfaces and cavities
lined with quartz crystals. The blending of the characters of agate,
and of fossil wood, seems to have been generally effected, by the
accumulated investments of the drusy crystals, just mentioned,
formed by the transudation of the clear silicious fluid, into the in-
terstices, and round the surface of the saturated bituminous wood.
The substance and opacity of the altered wood will, however, ge-
nerally prevent that transparency, those linear marks, and those
other appearances, which generally characterize the modifications
of silex to which the term agate is given. In one specimen, how-
ever, now before me, such appears to have been the tenuity and the
smallness of quantity of the bituminous wood, as to have allowed
the silicious matter, with which it is involved, to possess a consi-
derable degree of transparency ; and in the specimen depicted at
PL VIII. Fig. 3. and 5. of the starry stone of Chemnitz, the tubuli
are filled with agatine matter, conspicuously displaying those .marks
which characterize, what is termed, the fortification agate.

JASPERIZED wood is never of itself transparent, nor has any crys-
talline iilinitions, except such as sometimes appear to have been.

334

produced by the filling up of little cracks in the stone, by a sub-
sequent infiltration of a. silicious fluid. Its fracture is conchoidal,
very rarely splintery ; its lustre is dull, and its hardness varies with
its proportion of silex. The general characters and properties are
such, as readily lead to a knowledge of the nature of its composi-
tion. The veined or cloudy appearance of these stones rnay, in gene-
ral be very easily traced to the introduction of fine earthy particles,
between the detached masses of bituminized fibres of the fossil
wood, which have been all consolidated together by a subsequent
infiltration of a solution of silex. The specimen, of which the po-
lished section is figured at Plate II. Fig. 8. will serve to point out
how much this opinion is favoured by the appearances yielded by
this species of wood. The examination of jaspers has shown that
they generally contain silex and alumine, and even other earths, in
different proportions ; whilst the, folio wing experiments corroborate
the idea of bituminous matter entering, in a small proportion, into
the composition of this species of fossil wood.

Sixty grains of jasperized wood, reduced to powder, were mixed
with double the quantity of purified pot-ash, purified by Mr. Allen,
to which was added a sufficient quantity of distilled water, to dis-
solve the pot-ash. The powder which settled, and which was nearly
white when dry, but became darker on being wetted, in about four
or five days, showed a line of darker matter on the surface of the
precipitate ; which, during a month, continued to increase, when it
seemed to constitute, in bulk, about one fourth of the whole preci-
pitate. Half this precipitate, added to colourless sulphuric acid,
evidently darkened it : but willing to avail myself of the kindness of
my friend Mr. W. H. Pepys, whose well-known abilities would stamp
unquestionable authority on the results of his experiments, I re-
quested that gentleman to subject the remainder to an examination,
for the purpose of ascertaining the presence of carbon. According
to his obliging communication — the separated precipitate, after

335

having been washed with distilled water, and dried at 212° Wedg-
wood, weighed 1.3 grain. Upon projecting a small portion in colour-
less sulphuric acid, nearly boiling, sulphureous gas was evolved, and
the acid slightly blackened. On projecting of another portion
in boiling nitrate of pot-ash, gas was liberated, without sparks, or
scintillation. There are undoubtedly, Mr. Pepys remarks, difficul-
ties in ascertaining from what source the carbon may have been
derived ; the purest, and most caustic, alkali obtaining carbon in its
treatment with alcohol, which mechanical means alone have yet
been able to separate. Willing to obtain some more information
with respect to these volatile matters, w"hich might have escaped at
212° Wedgwood, I made the following experiment.

One hundred and eighty grains of jasperized wood, taken from a
part where the ligneous form was most apparent, were placed in a
glass retort, over the naked coals. When the bottom of the retort
became red hot, a vapour became visible in its upper part, and the
neck became discoloured by a light brown tinge, several small drops
of water collecting in it at the same time. The bottom of the retort
beginning now to run, the process was stopped. Upon examina-
tion, when the vessels were cold, the matter which had coloured the
neck of the retort, appeared to be in too small a quantity, to de-
termine its nature with any approach to precision. The water had
very little taste : but both the retort and receiver yielded a very
pungent, empyreumatic bituminous smell ; which the latter retained
for several days. This experiment, though imperfectly performed,
seems to be sufficient to establish the fact, that some remains of
bituminized vegetable matter were still present in the jasperized
wood.

However great is the variety in which jasper is presented to our
observation, there is hardly any appearance which it bears, which is
not exactly borne by fossil wood. In one specimen of fossil wood,
now before me, the fibrous texture of the wood is evident, whilst it

336

at the same time displays all the characters of the jaspis sanguinaris,
or blood-stone. Jasper, indeed, manifests so frequently the indu-
bitable traces of wood, as to give room to believe that its origin
has been derived much more often from vegetable composition, than
has ever been supposed. It has often occurred to me to notice, in
a specimen of polished jasper, appearances which, though striking,
conveyed no idea of vegetable remains ; but which obviously did
so, after the judgment had been aided by the examination of ano-
ther specimen, which at the same time that it possessed the same
general features, and characters, of the former specimen, manifested
more plainly the marks of vegetable origin. Specimens of jasper,
which excite no suspicion of their dependence on vegetable decom-
position, in the minds of those unused to such inquiries: but which
display indubitably such an origin, to those who have been in the
habit of examining specimens of fossil wood, are very frequent ; so
frequent, indeed; and so strongly do I find that observation extends
the right of their claim Jo such an origin, that I can hardly help
concluding, that many of the jaspers owe something in their com-
position, to changed vegetable matter.

Yours, &c-

33?

LETTER XXXV.

OPALINE WOOD... .THE RESULT OF THE UNION OF SILICIOUS AND

SOFT BITUMINOUS MATTER.

\V E shall now proceed to the examination of that kind of sili-
cious wood, in which the influence, and, indeed, the presence, of
bitumen appears to be still more apparent.

Opaline wood, Holz Opal of the Germans, Quartz-resinite xyloide
of Hauy, or silicized bituminous wood, is characterized by a peculiar
waxy, or rather, resinous lustre. Its fracture is conchoidal, and it
generally shines with the particular lustre just described. Sometimes,
the fibrous structure of the wood which remains will so direct the
fracture, that the fragments will be linear, or laminated. Its specific
gravity is from 2.045 to 2.675 ; and its hardness is such, that it will
frequently yield sparks freely, on collision with steel.

In this, as well as the other kinds of petrified wood, we are asto-
nished at discovering the nice state of preservation, in which the
fibrous structure of the wood exists, whilst it has undergone so vast
a change in the nature of its substance'. This, it has been already
remarked, appears to have been accomplished by the bituminiza-
tion of the wood itself; and in this kind the bituminization appears
to have been more perfect than in the preceding kind. By this
process, although the disposition of the fibres is frequently not at
all altered, its nature is changed ; and it is rendered susceptible of
an impregnation, with a fluid holding earth in solution.

The specimen depicted at PL II. Fig. 7- appears strongly to cor-
roborate this opinion respecting the conversion of the ligneous into a
bituminous substance, and its subsequent impregnation with silici-
ous particles. In that specimen is a knot of the wood, which differs,

VOL. i. xx

338

not in the least, in its appearance, from the knot in a piece of
recent wood, but is perfectly impregnated with silicious matter*
Is it possible, that the change, which this knot has suffered, could
have been effected, by an abstraction of the greater part, or, of the
whole, of its original constituent parts, and a substitution of par-
ticles of a totally different nature ? Its hardness,- and its closeness
of texture, must oppose an insuperable bar to the supposition;
whilst the mysteriousness of the change is entirely dispelled, by
admitting the7 softening operation of bituminization, and the conse-
quent admission of silicious matter.

But another circumstance, peculiar to this species of fossil wood,
requires a particular inquiry ; the result of which cannot but affect
the opinion just noticed. This circumstance is the peculiar lustre
which this species of wood displays : its fracture, in general, exactly
resembles that of newly-broken resin; and, generally, the lustre of
its external surface approaches, as near as possible to that which
would have been produced by pouring over it a thin coat of melted
resin, or of fine varnish.

In the specimen of a petrified root, represented in PI. II. Fig. 2.
this kind of coating, thinly spread, covers and softens down all the
asperities of its surface : and in Fig. 3. of the same Plate, the larger
pores seem to have been diminished, and some of them obliterated,
by the diffusion of this matter. The rough edge of the specimen,
Fig. 4. of the same Plate, also derives a bright gloss from this seem-
ing resinous varnish.

Struck by this appearance, the celebrated Hauy terms it, as we
have seen, quartz resinite xyloide*; and Mr. Walch's attention was
particularly excited by this peculiar resinous or waxy gloss, which he
endeavoured to account for, by supposing that this petrified wood
had. been impregnated by a peculiar spathose matter; which had

* Trait6 de Mineralogie, torn. ii. p. 139.

339

0

been deposited, whilst in a fluid state, and afterwards congealed.
There appears, he says, commonly, in this wood, something which
resembles amber, or resin; and which has, by some, been actually
supposed to be so, and to have assumed a stony hardness. This
he, however, concludes is not the case ; but believes that this sub-
stance, as he had already asserted, must actually be a particular
species of spar*.

Nothing certainly, as far as the evidence of the eye can be ad-
mitted, can more strongly favour the opinion, that the formation
of this species of fossil wood has depended on a combination of
silicious and bituminous matter, than the peculiar lustre which
it possesses ; which is precisely such as might be expected from
the mixture of these two substances. Different specimens, indeed,
seem to display the bituminous Wood in all its several degrees of
change ; from its first assumption of a bituminous nature, to the ac-
quiring of the state of pure translucid bitumen; and evince its hav-
ing obtained, in these several states, its present degree of hardness,
from the introduction of the silicious matter. In such varieties of
this fossil wood, as manifest evident and strong traces of the original
fibres, there seems to be reason for supposing, that the wood had
not undergone the bituminizating operation, to such a degree as to
have been thereby rendered a fluid bitumen. But that the wood,
previous to its impregnation with silicious matter, had been so far
affected by its bituminization, as to have been rendered soft and
yielding, is evident from the appearances which specimens of this
kind of fossil wood generally yield. Their fibres will generally be
seen disturbed, and thrown out of their natural direction ; not as if
broken, but as if displaced whilst in a yielding state, and thrown
into gentle contortions and undulations. An idea of what is here
meant may be furnished by a view of PI. II. Fig. 7.

* Recueil des Monumens dcs Catastrophes, &c. torn. iii. p. 32 and 39.

340

In Plate I. Fig. 1. is represented a specimen of bituminous wood
dug up at Blaekwall ; whilst digging for the purpose of forming the
East-India docks. This specimen, as is often the case, displays no^
very decided traces of its original form : the fibres are irregularly-
grouped, and seemingly agglutinated together; leaving proporti-
onate vacuities between them. Allowing imagination to fully imbue
this mass, with silicious matter, a substance resembling the common
silicious wood will be formed. The collected bundles of fibres
will manifest its origin ; and the silicious matter, preserving its pel-
lucidity in their intervals, will testify the nature of the impregna-
tion, where the original arrangement of the fibres is almost lost.
Thus may be illustrated the formation of such specimens as are
represented at PL II. Fig. 8. and PI. III. Fig. 9-

In many beautiful specimens of opaline fossil wood, the fibrous
substance may be seen passing through various gradations of change.
On the external surface, as at PI. II. Fig. 9. and at PL III. Fig. 8.
may frequently be seen the silicized fibre, nicely preserved, still
retaining its natural colour, and not partaking at all of the resinous
gloss, observable on the other parts of the same mass ; whilst, as the
same fibrous appearance enters into the substance of the mass, its
lines are softened down, by its assuming this resinous-like appear-
ance, and a much greater mellowness of colour ; and it is at last
entirely lost in the prevalent colour of the whole mass. Instances
of this kind are frequently met with, and may be particularly
noticed in the two specimens to which you have been last referred.

This appearance of the ligneous structure, on the external part
of a specimen, and its gradual disappearance, on the internal part,
is frequently to be perceived : sometimes also* whilst the external
part thus preserves the appearance of wood, this appearance will
almost suddenly be lost in the internal part, which will have ac-
quired a very high degree of transparency. This circumstance is
particularly observable in PL III. Fig. 8. where the external surface

341

is formed by a thin cortical coat, exactly resembling that of the
inner cortical investment of recent wood. Another form, which, in
these instances, the external surface sometimes, bears, is that of ap-
parently dried, and withered wood, as at Plate II. Fig, 9. Both in
this, and in the other specimen the seeming cortical surfaces are per-
vaded by silex, but appear to be but little changed by bituminiza-
tion. This may assist, in accounting for their not possessing the re-
sinous lustre, which distinguishes the rest of the mass: numerous
observations seeming to point out, that the bark, and dry withered
wood, are not so susceptible of bituminous change, as those parts
in which the woody fibre was unimpoverished.

Another circumstance, hitherto inexplicable, demands next to be
noticed. In many specimens of silicious fossil wood, are found
disposed, in and about it, distinct masses of a substance, bearing
so exactly the appearance of bitumen, as would leave no doubt of
its being of that nature, were it not that examination discovers it to
be a substance, containing a considerable proportion of silex. The
explanation of the formation of this mysterious substance is, un-
doubtedly, accompanied with considerable difficulty. After having
examined it in every point of view, I discover no mode of explain-
ing its formation, but by supposing it to have been actually a fluid
dark bitumen, which, by the medium of the water, we have already
seen it contains, has become impregnated by silicious earth.

The general appearance of this seeming bituminous substance
appears strongly to point it out, as having existed in a soft state:
some pieces of it appearing as if their eminences had been rounded
off by slight friction. In the specimen figured at Plate II. Pig. 4.
which has very much the appearance of a piece of fossil deal wood,
this black bituminous-like matter almost covers one end, and pe-
netrates into the substance of the wood, as may be seen by the
section of the same specimen, at Fig. 5. of the same Plate: the
wood having split at the end, as if from dryness ; and the bitumen,

in a fluid state, having apparently filled the rifts thus produced.
This section, being polished, serves also to show, that both of the
substances, which enter into the composition of this specimen, are
thoroughly penetrated by the silex : both having acquired the same
brilliant polish, from the lapidary's wheel.

Another circumstance may be mentioned, in addition to those
which have been already adduced, in confirmation of the opaline
woods being 'formed, by the combination of bituminous wood and
silex ; which is, that they sometimes are marked by depressions,
evidently from pressure against contiguous bodies; which depres-
sions have every appearance of having been made, whilst the fossil
wood was about the firmness of wax, or of tallow. In a specimen
which I obtained, since the Plates intended for this Work were
finished, a circumstance occurs, which seems to prove irrefragably
thfe facility with which bitumen and silex may thus unite. One side
of this specimen presents the ordinary appearance of bituminous
wood, although the whole is well impregnated with silex. On the
other side, part of the wood had begun to suffer a change into jet,
and is also covered, in detached spots, with a substance possessing
that particular varnish-like lustre which has been so often mentioned,
but is of a jet black. Many parts of the specimen are sprinkled
with drusy crystals of quartz, which, in the neighbourhood of the
jetty part of the wood, are also of a jet black, evidently from the
intermixture of the fluid black bitumen with the silex, of which
the crystals are chiefly composed.

As silicious, and even opaline wood, has been found in almost
every part of the world, and as mention has already been made of
many places where it is particularly abundant, all that remains ne-
cessary appears to be, to give a slight sketch of the differences
which have been remarked, in the silicious woods of various parts.
Silicized wood has been discovered in various parts of England,
but seldom any which displays any thing of the opaline lustre. A

343

specimen, however, which I possess, from the neighbourhood of
Wooburn, in Bedfordshire, has it in a considerable degree.

The petrified wood found ii> the neighbourhood of Lough-Neagh,
which has been spoken of in a former part of this volume, is evi-
dently wood, which, having suffered bituminization, has afterwards
been impregnated with silex, partially or totally, and in various
degrees ; and has also, in some instances, become invested by the
lapidified surrounding matrix. On examining a handsome specimen
of the Lough-Neagh wood, in the British Museum, being of that
kind which has been described as possessing the unchanged, conti-
nuous with the petrified wood, I was convinced of its being bitu-
minized wood, in some parts involved in, and in others adherent
to, a coarse, hard, argillaceous matrix. Mr. Barton himself says,
" The smell (of the woody part of these stones) is not resinous, yet
it is a strong smell, when it is burning in a large quantity; and a
faint smell of the same kind, when only the stone is burning; per-
haps, he says, this is the scent of bitumen*." The other kinds of
Lough-Neagh wood are undoubtedly of the silieious- kind; he says
of them, " They cleave like wood ; they contain abundance of fire,
as may be proved by using them as flints, and by rubbing them one
upon the other, even when they are wet; and they bear the fire
surprisingly ; for although they are easily made red hot, yet they
neither burn to lime, nor vitrify/'

In Switzerland, and particularly in the neighbourhood of Bayern^
beautiful specimens of the silicized bituminous wood are found^
bearing a very close resemblance to. the recent wood in colour and
figure. In Lithuania a rare kind is found, in. which, though it ma-
nifests no disposition to the transparency, which the opaline wood in
general shows, it possesses, in some parts, the opaline lustre, and has
obviously, from the soft state in which it has existed, had its fibres

* Lectures in Natural Philosophy, &c. by Richard Barton, B.D. Dublin, 1751, p, 89, &c.

344

so blended together, in a confused mass, that were it not for the
knots, which are very evident, its ligneous origin would not be
detected. Switzerland, various parts of Germany, Saxony, Hun-
gary, and Bohemia, have indeed hitherto produced the most beau-
tiful specimens. From the chain of mountains, formerly named
Taurus, in Natolia, from the neighbourhood of Pergamo, and from
some of the mountains of Italy, very interesting specimens are ob-
tained. The fossil wood of Coburg, in the Circle of Franconia, is,
in general, very beautiful ; since it equals any in hardness, and is,
consequently, susceptible of as fine a polish as any ; and, at the
same time, displays, very determinately, the ligneous texture. Bam-
berg also furnishes a fossil wood, very nigh approaching, in beauty,
that of Coburg. The wood which is dug at Rockenhausen, and
from the mountain at Kyfhausen, is eminently conspicuous for its
beauty; its hardness almost equalling that of agate, and its in-
termixture with a white earth giving it also the character of jasper:
an oxide of iron, frequently of a bright red, tints it very beautifully
in various parts ; whilst a few, but decided traces of wood, deter-
mine the wonderful change which it has sustained. The fossil wood
of Chemnitz seldom displays very clearly the characteristic marks
of the wood; it giving rather the idea of agate, or of jasper, which,
in hardness, it fully equals.

That Saxony and Hungary, whence the noble opal is chiefly ob-
tained, should abound in those silicious woods which nearest resem-
ble the opal in their lustre, is a circumstance which here demands
our particular attention, since it will yield us some additional evi-
dence, whilst determining on the question which will next require
to be agitated.

Yours, &c.

345

LETTER XXXVI.

EVIDENT AFFINITY BETWEEN SILICIZED BITUMINOUS, OR OPA*
LINE WOOD, AND PITCH-STONE. ...ANALYSIS OF OPALINE WOOD
....OF PITCH-STONE. ...SIMILARITY INFERRED.

A.S that particular character, a waxy, or resinous lustre, is evi-
dent in those substances which, though now chiefly formed of
silex, display the most evident marks of their having been wood ;
and as nature does not multiply her agents unnecessarily ; it does
not appear to be unreasonable to suppose, that particular appear-
ance has been derived, in every other stone which possesses it, from
the same source, as that which has furnished it to the fossil wood.
You will already have perceived, that I am leading you, with as
little abruptness as I can, to the consideration of an opinion, which
I suspect must demand some little management to secure it a
favourable reception. That many of the pitch-stones, the semi-
opals, and perhaps the noble opal itself, derive their peculiar cha-
racters from certain portions of the vegetable matter, which, having
been buried at very considerable depths, have undergone a parti-
cular change in the combination of their constituent principles ;
and in that state, has been intimately united with silex. We will
now proceed to examine, how far this position is supported, by the
physical and chemical properties of these substances.

Among the most beautiful and frequent specimens of the opalized
woods are those which, from their near resemblance to pitch-stones,
mineralogists have termed LIGNIFORM PITCH-STONES, the QUARTS

VOL. I. Y Y

346

RJSSINITE xYLoiDEof Hauy» In these the characters of wood are
so distinctly marked, that no one can entertain the least doubt of
their having originated from wood. The resinous, or waxy lustre,
which they manifest, has been already examined, as to the degree
of evidence it affords of the wood having existed in a bituminous
state. Their fracture, perhaps, serves also to further prove their
ligneous origin ; since although this is in general conchoidal, it will
frequently, when longitudinal, be splintery, and even fibrous, in the
direction of the fibres of wood. Their colours vary very much,
from milk white, through all the shades of brown and yellow, to
green, red, and black; but their most frequent colours are those,
which approach so near to that of the original wood, blended with
that of common resin, as to corroborate strongly the idea of the
wood having been softened down, into a resiniform substance, pre-
vious to its impregnation with silex. Their transparency, which is
sometimes such as to admit light through them freely, and even,,
when in thin slices, such as to allow objects to be seen through
them, is a circumstance which it is impossible to account for in
any other way so well as by supposing the wood to have been ren-
dered a clear bitumen during its first change. A specimen of this
kind of pitch-stone, or fossil wood, possessing in its internal part a
considerable degree of transparency, whilst the external part bears
the appearance of recent wood, is figured in Plate III. Fig. 8.
These fossil woods are also characterized by a circumstance which
has excited the admiration of mineralogists, and which at the same
time seems to manifest the intermixture of some substance with the
silex which does not seem to exist in any other stone of the silicious
genus— although they appear, from their peculiar kind of lustre, to
be little harder than resin, and sometimes give fire with steel with
difficulty, they yet are more difficult to be scratched than many
that do this more freely.

The combination of bitumen and silex, in these specimens of

347

pitch-stones, and fossil wood, is rendered still more probable, and
even certain, by the chemical properties they exibit when subjected
to the action of fire, and of other appropriate re-agents. 120 grains
of opaline wood, from the specimen at Plate II. Fig. 4 and 5, were
reduced to a coarse powder, and digested without heat, for two
months, with 180 grains of pure pot-ash, and half an ounce in mea-
sure of water, when the whole of the silicious matter became nearly
dissolved, forming a thick liquor silicum ; whilst the sediment which
remained was considerably darkened, and became exceedingly light
and flocculent ; bearing the appearance of carbonaceous matter.

But to render the knowledge of the constitution of opaline wood
quite perfect, I again had recourse to the abilities of Mr. Pepys ;
whose excellent report I here subjoin.

SPECIMEN OP OPALINE WOOD*,

Of a splintery fracture — gives fire with steel — a fine polish — of a brownish

yellow colour.

o

= «

'A portion digested with alcohol, at ebullition, yielded no precipitate,
nor cloudiness, on mixture with water.

8 S Pulverized, and digested, with concentrated sulphuric acid, nearly boil-
ing, blackened the acid slightly.

i Projected, with nitre, into a red-hot silver crucible, produced no defla-
* I gration, nor appearance of carbonaceous matter.

Digested with the acids — sulphuric, nitric, and muriatic-— it produced
no change, except, as before noticed, with the concentrated sul-
phuric.

Heated with caustic pot-ash, in a silver crucible, it dissolved, and ran
per deliquium, on exposure to the atmosphere.

* Plate II. Fig. 4. and 5.

•c
o

I

"o

CO

348
THE ANALYSIS.

100 grains of the pulverized substance was heated with 200 grains of caustic
pot-ash, in a silver crucible. The mass was then dissolved by 12 ounces of
distilled water, and filtered.

B

To the solution A, nitric acid was added, as long as a pecipitate formed.
It was then further diluted, boiled, and filtered. The precipitate obtained
dried at 212°, weighed 126 grains Cheated to redness, 110 grains.

As the precipitate B might contain a small portion of the pot-ash, it was
boiled with 200 grains of marine acid, diluted, and filtered; when heated to
redness, weighed 94 grains.

The filtre of the process A contained no extraneous matter. The solution
of nitrate of pot-ash B, being completely neutralized, was crystallized ; and
from the mother liquor a precipitate of silex was obtained : weighed 1.5 grain.

E.

The solution of muriatic acid c was neutralized by carbonate of pot-ash,
and boiled, and proved free from precipitation.

100 parts of opal wood contain

Grains.

Silex ... c 94

D 1.5

Loss . 4.5

100

. Anxious to have the presence of carbon, in the opaline wood, still
more plainly manifested, I again troubled Mr. Pepys; the result of
whose obliging and ingenious labours I shall give you, in his own,
words; only omitting his well-adapted contrivance, for conducting
bis experiment with security and effect.

DEAR SIR,

CONCEIVING that a portion of the opaline wood being mixed
with twice its weight of purified nitre, and exposed to heat, if carbon was
present in the stone, it would unite with the oxygen of the nitre, and produce
carbonic acid gas, I proceeded to the following experiment.

Into a coated glass retort, with a conducting tube entering a bottle of lime-
water, 50 grains of fossil wood, and 100 of nitrate of pot-ash, were introduced ;
and it was then surrounded with heated charcoal. After the expansion of the
atmospheric air, an absorption took place, from the fusion of the nitre; this
was guarded against, by lifting the conducting tube from the water ; as soon
as gas was liberated, it was again immersed, and a copious precipitation, and
cloudiness of the lime-water, ensued. This continued for some minutes j it
was then succeeded by the liberation of oxygen gas, with nitrous gas, occa.
sioning no precipitation in fresh lime-water. In 36 minutes the retort was
perfectly white hot, and slight absorption began to take place : the retort was
then removed, and when cool was broken : the mass was found strongly agglu-
tinated, possessing a tinge of pink.

I am, with sincere respect, yours,

W. H. PEPYS, jun.

The presence of carbon having been thus proved, my next eager
wish was to endeavour to discover the nature of this substance,
which thus contained carbon as a principle ; entertaining an ex-
pectation, that some evidence would appear, that it was vegetable
matter, which had undergone the biturhinizating process, or fer-
mentation : 1 therefore requested Mr. Pepys, without mentioning
my conjecture, to submit a portion of similar fossil wood, with that
which had been employed in the foregoing experiments, to simple
distillation, over a naked fire. This request was kindly complied
with, and the result appears in the following letter.

SIR,

AGREEABLE to promise, I have made the experiment you requested.

250 grains of the opaline wood were pulverized, and placed in a coated

glass retort ; to which a tubulated receiver, with a conducting pipe, leading

into a bottle of lime-water, was luted. Gradual heat being given, rarefied

the atmospheric air in the vessels, which passed through the lime-wafcer ; in

350

15 minutes this ceased, and the retort being red .hot, a small quantity of
water dropped from the beak into the receiver ; and, as it there collected, an
oily, or sublimated film, appeared on its surface. The strongest heat of this
furnace was continued about an hour ; when evident absorption taking place,
and the distillation ceasing the operation was stopped. Upon opening the
receiver, a strong empyreumatic smell was observed. The liquor obtained has
a dull yellow colour, with small scales on its surface, and in quantity about
20 drops ; the greatest part of the scaly substance adhered to the receiver on
pouring out the fluid. The substance in the retort was still pulverulent, but
much more white than when introduced. The liquid shows no acid properties,
by the test of litmus paper, or violets.

I am, with much respect,

W. H. PEPYS,jun.

The oily, or sublimated film, and the strong empyreumatic smell,
afford some reason for believing in the presence of bitumen in this
opaline wood ; but anxious, only for the discovery, and communi-
cation, of the truth, I wish you to suspend your opinion, until your
judgment has been aided by other corresponding experiments,
which I shall now adduce.

Common pitch-stone, that which displays no obvious trace of
wood, hols-opal of Emmerling, and, from its resinous or pitchy
lustre, the pierre de colophane of De Lisle, and the pierre de poix of
Daubenton, differs in no respect from the former kind, except in
the absence of those marks which give to that a resemblance to
wood. Believing this to depend merely on the bituminous wood,
which enters into the composition of this latter substance, having
become so fluid as to have had the remains of its fibrous structure
quite melted down, whilst in the former some of the fibrous struc-
ture remains, I conceive it not entitled to be considered as of a dif-
ferent family from the former, as has been done by the celebrated
Mr. Kirwan, and other mineralogists. In proof of this opinion, we
often see, in the same specimen, in one part, distinct fibrous appear-
ances ; in another part of the same substance, the fibrous appear-

351

ance, we perceive, is quite lost ; and, in the intervening part, the
gradual departure from a striped, to quite a plain appearance, may
be observed : whilst frequently the existence of the soft bituminous
state will appear, from the wavy and contorted directions of fibrous
stripes, which are indubitably of a ligneous origin. Nor does any
difference of physical properties exist between this and the ligni-
form pitch-stone already described. With respect to their chemical
properties, there exists a very close agreement, as will appear from
the following experiments.

Mr. Pepys exposed 50 grains of pitch-stone, and 100 of pure
nitrate of pot-ash, to the same treatment as he had subjected the
same quantities of opaline fossil wood and nitrate of pot-ash, and
reported that the phenomena which resulted were precisely the
same.

At Menil le Montant, also at Saint Ouen, near Paris, and in
several other parts of France, have been found a stone which is
of a greyish colour, sometimes mottled with blue on its surface,
opaque, generally of a tubercular form, and showing at its fracture
a slight lustre of the greasy kind. It was first described by Delabre
and Quinquet, who very properly considered it as- a new kind of
pitch-stone; its hardness, specific gravity, and fracture, as well as
its kind of lustre, warranting them in this opinion *. It was named,
from the place where it was first found, Menilite, and was consi-
dered as a variety of the pitch-stone, being therefore termed, by
some, blue pitch-stone ; but it has been supposed by others to be-
long rather to the magnesian genus of stones, such as the pot-stone,
steatites, and serpentine.

The experiments of the justly celebrated Klaproth, which induce
him to consider this fossil, as a variety of the semi-opal, approach-
ing to flint (feuerstein) serve strongly to corroborate the opinion I

* Journal de Physique, Sept. 1787, p. 21$.

352

have offered, of substances possessing this peculiar lustre, deriving it
from an impregnation with bitumen, and are in full accordance with
the experiments of Mr. Pepys. Mr. Klaproth introduced 100 grains
of this substance into a small glass retort, inserting its neck into a
bottle containing lime-water. The retort was placed between the
coals, or in open fire, and the heat gradually increased to the igni-
tion of its contents. At the very beginning there passed over some
drops of water, and soon after the lime-water in the receiver became
turbid. In this last, when the receiver was removed, a bituminous-
empyreumatic smell was perceived, which at first also seemed to be
somewhat ammoniacal. The pieces of the stone, in the retort,
were rendered Wack, and resplendent like jet ; but by a still longer
ignition, in an open crucible, they lost that black colour, and be-
came at first bluish; then grey white, losing, at the same time, three
grains more of their weight *.

The result of this operation, and particularly the bituminous-em-
pyreumatic smell, afford pretty strong evidence in favour of the
supposed nature and constitution of the substances of this genus.

Yours, &c.

* Analytical Essays, by M. H. Klaproth, p. 452,

35.3

LETTER XXXV1L

SEMI-OPAL EXPERIMENT OX SEMI-OPAL OF TKLKEBANY

OPAL. ...ITS WONDERFUL PROPERTIES.... A NA LYSIS BY KLAP-
ROTH.... HORN-STONE AND FLINT.

1 HE SEMI-OPAL is the next substance which, possessing this
kind of lustre, demands our attention : but, previous to making
any remarks on the nature of its constituent parts, it will be neces-
sary to determine the propriety of placing it among those substances
that possess the peculiar lustre, which I have supposed to belong
to those substances, which are formed by an intermixture^ of bitu-
men with silex. The reason for instituting this inquiry is, that
Mr. Kir wan describes the lustre of the semi-opal, and of the opal
itself, as being of the glassy kind; which, being admitted, would pro-
hibit both these substances from preserving the rank, which is here
allotted them. This character, however, a glassy lustre, 1 believe,
with the utmost deference to Mr. Kirwan, is not the legitimate lustre,
at least, of the real external surface of the opal, or of the semi-
opal. The lustre of its fragments, indeed, may be, and that which
it receives from the polish of art generally is, of that description :
but in an hyclrophanous opal now before me, which, when dry,
resembles a piece of white wax, and when in water is transparent,
and resplendent with purple and a vivid green, the lustre, even of
its polished surface, is decidedly resinous ; and, most undoubtedly,
the lustre of the actual external surface of the opal, that which was
in contact with the matrix, is almost always of the waxy kind. The
matrices, also, both of the opal, and of the semi-opal, frequently pre-
sent appearances, very strongly indicative of the presence of bitumen :
VOL. i. z z

354

detached spots will be frequently seen on them, in the neighbour-
hood of the opal, presenting an appearance, very nearly resembling
that which would be produced, by the spread of a fine resinous
varnish. I should have been much more disposed to hesitate, in
thus opposing Mr. Kirwan, on a mere object of sense, if I had not
been supported by one of the latest authorities, on such a point,
the Abbe Hauy, who places the opal, the semi-opal, and the hy-
drophanous opal, among those substances which, from their lustre
resembling that of newly-broken resin, he distinguishes by the ge-
neric term of quartz-resinite.

The analysis of Mr. Klaproth having been made, chiefly, with a
view to the ascertaining of the nature, and proportion of the earths,
contained in the substances he examined, the first part of his opera-
tion was, generally, ignition, in an open crucible; by which the water,
and other volatile matters, must have been indiscriminately dissi-
pated. Such was the mode in which he made an examination of
the brown-red semi-opal of Telkebanya ; and even thus a circum-
stance occurred, which did not escape his nice observation, and
which tends strongly to evince the probability of this semi-opal
containing a portion of that matter, on which I presume the pecu-
liar lustre of substances of this class depends. Mr. Klaproth was
surprised to find, on igniting this substance in the clay-crucible,
that its whole surface was covered with a fine scaly ferruginous crust,
of a metallic lustre, and attractible by the load-stone. This, Mr.
Klaproth says, is, indeed, an unexpected phenomenon; and is the
more remarkable, from the iron, so strongly oxided, as it is in this
fossil, being thus reduced to the reguline state, so as to obey the
magnet ; and this, without any admixture of charcoal, or any other
substance of a nearer affinity with oxygen*. If I were constrained
to rest the support of the opinion I have formed on any single ex-

* Analytical Essays, p. 449.

periment, 1 hardly know any which I should prefer to this of Mr.
Klaproth's. According to the opinion offered, this substance should
contain bitumen, into the composition of which carbon enters, in
an abundant proportion — and, by the experiment, an effect is pro-
duced which excites the astonishment of this excellent chemist;
because it is that effect, which he would have expected from the
presence of charcoal ; which he had no conception entered into
the composition of the substance which was the subject of his
experiment. Having obtained this satisfactory evidence, from the
analysis of the semi-opal ; the task remains to ascertain, whether
any traces of the substance are to be discovered, in the opal itself.

The OPAL, opal edler, gelber opal, Werner, the noble opal of
some, and the oriental opal of thjk jewellers, in addition to the
general characters which distinguish this class of fossils, possesses
the astonishing property of displaying, in a strong light, the most
vivid and beautiful colours, which continually play on the eye, with
varying splendour, on the least change of position. From that
spot which, the instant before, showed a beautifully bright green,
or purple, a rose-cotoured flame suddenly darts forth, forming what
the amateurs of this stone term, the jire of the opal. But descrip-
tion can furnish only a very imperfect idea of the brilliant display
of colours yielded by this admirable, and inestimable jewel. Our
admired poet Thomson, indeed, appears to have succeeded, as far
as the powers of language could enable him. It is in his address
to the Sun, where he thus speaks of the wonderful properties of this
highly elaborated work of nature.

The unfruitful rock itself, impregn'd by thee,
In dark retirement forms the lucid stone:
The lively Diamond drinks thy purest rays,
Collected light, compact, that polish'd bright,
And all its native lustre let abroad,
Dares, as it sparkles on the fair one's breast,

356

With vain ambition emulate her eyes.

At thee the Ruby lights its deepening glow,

And with a waving radiance inward flames.

From thee the Sapphire, solid ether, takes

Its hues coerulean; and, of ev'ning tinct,

The purple streaming Amethyst is thine.

With thy own smile the yellow Topaz burns:

Nor deeper verdure dyes the robe of Spring,

When first she gives it to the southern gale,

Than the green Emerald shows: but ALL

Thick through the whitening OPAL play thy beams,

Or, flying several from its surface, form

A trembling variance of revolving hues,

As the site varies in the gazer's hand.

SEASONS, Summer, 1. 140.

Cto

Mr. Klaproth, having subjected the noble opal, both in its ordi-
nary, and in its hydrophanous state, to the test of his accurate
examinations, is induced to conclude", that the difference bet\yeen it,
common flint, and rock crystal, is only that which depends on a
difference in the state of aggregation*. From this same examina-
tion, I am led to make a widely different inference ; and to con-
clude, that the same bituminous matter, which has been assumed
to be present in the other stones of a waxy lustre, is also present
in J:he opal; and that it is by its admixture with the simple, pure,
silicious earth, that the opal is produced. In two of Mr. Klaproth's
experiments, which being made merely to ascertain the nature of
the earth existing in this stone, prove the quantity only of its vola-
tile parts, the real constituent parts of the opal are shown to be,

Gr.

Silex ....... 90

Water, and other volatile matters ... 10

100

* Analytical Essays, p. 44O.

357

Another experiment was made on one of those varieties of the
opal which are known by the names hydrophones, changeable opal, and
oculus inundi, which, besides possessing the remarkable property of
becoming transparent in water, and other Maids, are eminently
distinguished by manifesting, in that situation, the beautiful play,
or change of colours, peculiar to the opal. This analysis was made,
under those circumstances, which were calculated to yield some
knowledge of the nature of those constituent parts, which had been
dissipated, without examination, in the two experiments just men-
tioned ; and therefore is the experiment, on which we might, almost,
be allowed to depend the decision of the question — whether any
thing of a bituminous nature enters into the composition of the opal.
The result of this experiment is strongly affirmative of this fact;
and, indeed, seems to confirm the opinion I have ventured to ad-
vance, in a most striking manner. You must have perceived that I
have been regularly led on to the supposition of the presence of
bitumen in opal, by first noticing the impregnation of bituminous
wood with silex, by which was formed silicized bituminous wood ;
then tracing this into the opalized wood and the pitch-stone ; thence
to the semi-opal, and at the last to the opal itself: you will there-
fore readily conceive the satisfaction yielded by the analysis made
bv Mr. Klaproth, which afforded au result at once so unexpected
and decisive ; and so precisely accordant with the experiments of
Mr. Pepys, on opaline wood'.

One hundred grains of the hydrophanous opal of Saxony were
coarsely divided, or bruised, and ignited upon red-hot coals, in- a
small glass retort. At the end of this process there appeared, in
the receiver, an einpyreumatic water, covered with a thin greasy pel-
licle. The loss of weight arising.from this was 51 grains. Pursuing
the analysis, Mr. Klaproth was enabled to ascertain that 100 parts
of the hydrophanous opal, from Saxony, contain,

358

Gr.

Silex . . .............. ..... 9

Alumine ..... ............... 1.625

Volatile inflammable parts, and water . . . 5.250

100*.

The Opinion which I have ventured to offer, respecting the tran-
sition, if I may be thus allowed to employ the term, of bitumen;
into the noble opal, appears to be corroborated, and the fact to be
illustrated, by another modification of bitumen and silex, in which
the union of these two substances appears to.be incontestable. In
the specimens in which this combination occurs, and which evidently
are of vegetable origin, the external surface presents evident marks
of wood, which appears to have undergone but a slight degree of
bituminization. This ligneous coat is, in some parts, not more than
a sixteenth of an inch in thickness, and in some parts is so thin, as
merely to give the appearance of a film ; adhering to a flinty mat-
ter, of which the substance is formed. This substance differs in no
respect, in its appearance, from COMMON FLINT (gun-flint, feuer-
stein), except in being more dull and opaque ; as if it contained a
portion of dark-coloured bitumen, or petroleum : this appearance
being rather more conspicuous, towards the external surface ; it
gradually assuming the appearance of common flint; and, acquiring
a greater degree of pellucidity arid transparency, as it reaches
the. interior surface; and, in one specimen, it there assumes the
form and -appearance of a calcedonic stalactite.

The film, or coat, bearing indisputable marks of ligneous origin,
whilst the rest of the mass appears to be formed by the blending of
bitumen and silex, offers an appearance, not to be explained, without
some difficulty. An analogous circumstance is frequently observ-

* Analytical Essays, p. 444.

359

able in pieces of asphaltum and jet ; the bituminous change being
entirely completed, except at the surface, where the texture, and
sometimes the colour, with the other characters of the wood, will
be manifest. This ligneous appearance, as in the case above men-
tioned, is generally merely superficial ; although sometimes, indeed,
the fibrous appearance will extend for a quarter of an inch, or more,
into the mass of bitumen. The explanation which will be satisfac-
tory in the one instance, will also suffice for the other. We are, in
the first place, necessarily led to the conclusion, that, by the influ-
ence of some adequate cause, the surface of the wood had been
rendered less susceptible of the bituminous fermentation, than the
other part of the wood, and has therefore remained unaltered, whilst
the other part has completely undergone the bituminous change.
The causes to which this may be attributed, are either, first, a na-
tural disposition in the exterior surface of wood, and particularly in
the bark of trees, to resist the influence of the bituminous fermen-
tation : secondly, the previous impregnation of the external sur-
face, with some earthy, or metallic saline substance, which might
render it incapable of undergoing the bituminous change, so deep
as that impregnation might extend itself. This opinion is strength-
ened by the specimen, Plate III. Fig. 8, in which the internal part
is opalized, and rendered nearly transparent, whilst the external
part has the appearance of wood itself, and is marked externally,
in several parts, of a blue colour, as though it were impregnated
with carbonate of copper.

In the specimens above mentioned, in which the combination of
dark-coloured bitumen and silex is apparent, analysis appeared to
be unnecessary to prove the presence of the bitumen, it was there-
fore omitted, especially as it could not have been accomplished
without injuring two valuable specimens.

The examination of specimens of this kind, and of their transi-

360

tions in such a manner as to ascertain what volatile matters enter
into their composition, would, perhaps, sometimes evince the un-
expected presence of bitumen both in horn-stone and flint.

Yours, &e.

LETTER XXX VIII.

CALCAREOUS WOOD. ... DIM E FREQUENTLY HELD IX SOLUTION, IN

WATER VARIOUS FORMS OF DE POSIT ION.... CONFETTO DI T1VOL1

....QUARRIES OF TUFACEOUS STONE... .STALACTITIC CAVERNS.

•

1 HE mineralized wood, of which we shall treat in this Letter, is
of such a nature as will not oppress us with such difficulties, whilst
endeavouring to ascertain its mode of formation, or the nature of
its constituent parts, as were opposed to our inquiries, respecting
the same subjects, whilst examining silicious wood ; ^ince the na-
ture of the mineralizing matter is such as to allow of its removal by
such agents as will not act-so destructively on the vegetable matter,
which forms the substratum of the fossil.

CALCAREOUS WOOD, wood impregnated with lime, is neither so
hard nor so heavy, as silicious wood ; it may be scratched by a
knife even in its hardest parts ; and in some parts will allow of
being cut, almost like recent wood; its hardness and its gravity,

361

depending on lie degree of its impregnation with earthy particles,
are of course variable and indeterminate. If exposed to tr"> action
of the mineral acids, its stony parts are dissolved with effervescence,
and the vegetable parts are left : by the action of fire the stony
parts are reduced to pure lime, whilst the vegetable matter is con-
sumed.

As in the silicious, so in this species of fossil wood, it is evident,
that the lapidifying matter has been deposited from a fluid holding
it in a state of solution. Pursuing, therefore, the same course as
was chosen, whilst endeavouring to determine the mode in which
silicious wood had been formed, we will endeavour to discover the
source of this impregnating matter. But little difficulty, however,
presents itself here, since in almost every part of the world, springs
and rivers exist which contain a considerable proportion of calca-
reous earth, which is deposited in the form of that species of car-
bonate of lime, which is termed tufa, on the sides of the channels
through which these waters flow ; and, indeed, on every substance
they meet with in their current.

In England the waters of this kind are very numerous, particu-
larly in the counties of Derby, York, and Somerset; but indeed
their occurrence is much too frequent to allow of being particu-
larized ; a few only of the most remarkable circumstances respect-
ing them can be noticed.

Dr. Plot relates* that, in Oxfordshire, there are incrusting waters
at Somerton ; at North-Ashton, in a field north-west of the church ;
in the parish of St. Clement, in the suburbs of Oxford ; about a
a quarter of a mile distant, on the right hand of the first way that
turns eastward, out of Marston-lane. But much better for this
purpose, he observes', is the water of a pump at the Cross Inn, near
Carfax, in the city itself.

* The Natural History of Oxfordshire, p. 34.

•

VOL. I. 3 A

362

The Doctor also mentions several springs of this kind in Stafford-
shire, and remarks that lapidescent springs deposit thin earthy
matter on some plants, and not on others, though growing together
in the same group. Mr. Wallis* also speaks of a brook at Simon-
bourn, where, he observes, the mosses and liverworts become stony ;
whilst the primroses and geraniums hold up their heads, and retain
their native hue.

Dr. Plot also relates -f-, " that at Daulton, on the south side of
Mendip, the workmen saw out of great blocks of stone, of four
or five ton weight, which have been dug from the quarries there,
large pieces of fair cleft oak included in the midst of them/'
Speaking of the growth of stone, the Doctor proceeds to say,
" This is as indisputable a proof as any I have met with, except
one at Newcastle-under-Line, in this county; where, at a place
called the Gallows-tree (the ancient place for the execution of the
malefactors of that town), there was found, within memory, in a
firm block of stone, dug out of the quarry there, an entire skull of
a man, with the teeth in it, &c. whereof Mr.Weever, an alderman of
that town, told me he had one, long in his possession : which place,
when used for executions, 'tis like might be nothing else but sandy
land, wherein they used to bury the executed bodies, which in pro-
cess of time has thus turned into stone/' The deposit of lapideous
matter from the waters in the neighbourhood of Mendip has been
lately instanced, according to a very interesting paper on the sub-
ject, by its having thus partly filled up a cavern, and having in-
crusted, in a Tery curious manner, human bones, which had been
there deposited.

.Near the western bank of the Derwent, at Matlock, is a spring,
well known by the name of the petrifying spring, and by the va-
rious substances, which accident and contrivance has occasioned to

* The Natural History of Northumberland, p. 24.
t The Natural History of Staffordshire, p. HI.

be invested with the calcareous m'atter which it deposits, such are
twigs of wood, moss, birds-nests, &c. Even old wigs and hair-
brooms are subjected to the power of these waters, to furnish sub-
jects of amusement to the visitors at this place.

The waterfalls of Italy used also to supply the light-hearted with
amusement ; small white oblong, or round concretions, being formed
by them, which have much the appearance of sugar-plums. These
are put up in boxes, which are ornamented in the mode usually
employed for boxes of sweet-meats, and thus offered to strangers,
who, being frequently thus deceived, become the subjects of a harm-
less laugh. Those concretions, which are thus employed at Rome,
are known by the name ot'Confetto dt Tivoli, from their being chiefly
obtained from the river Tiverone, the Anio, Anien, and Anienus, of
the ancients, which waters the charming town of Tivoli, the favourite
Tibur of Horace. The same name is, however, generally used for
such as are obtained from the other rivers.

A much more rational and pleasing application of this natural
process is made at the baths of St. Philip, in Tuscany. Dr. Leo-
nard Vegni has established there a manufactory, to precipitate this
fine tufa on medals and bas reliefs, and to get by that means the
finest impressions. He causes this hot incrustating water to fall,
from on high, into a large vessel, and to break upon a wooden cross ;
whereby it is separated into a fine spray, and directed against the sides
of the vessel, on which, all around, the medals or bas reliefs, or their
mouldings or forms, are hanging. The falling or breaking of the
water imparts a greater impulsion to its drops, and to its turfo or
tartaro ; which, without this manipulation, would be but farina-
ceous, friable, and spongy. Air. Ferber, from whose work the above
account of this process is extracted, says, that Dr. Vegni has suc-
ceeded already in casting busts of this tufo, and he soon hopes to
cast statues of a natural size*. Since the publication of the above

* Travels through Italy, p. 245.

364

account, I learn that Dr. Vegni has applied the waters at Tivoli to
the same ingenious purposes.

Pere Feuillee relates, that the petrifying waters near Guankaba-
lika are applied to similar purposes ; he having seen many very fine
statues and vases in the churches at Lima, which had been thus
formed in moulds, by earthy depositions.

Some waters are so replete with earthy particles, as soon to clog
up the channels through which they are conveyed. A remarkable
instance of this kind occurred at High Littleton, in the county of
Somerset, about midway between Bristol and Wells. A pipe- had
been erected to convey away the waters, which had incommoded
the workmen in a coal-pit ; it was formed of elm, in shape nearly
a long square, being about seven inches and a half one way, and
four inches and a half the other. Through this, placed perpendi-
cularly, the water was conveyed down to the level, or passage out,
the trunk being about fourteen yards in length.

This trunk, having thus been fixed up in the latter end of the
year 1766, was in about three years time, or rather less, found to
be much obstructed, and stopped up, so that, in August 1769, the
miners were obliged to take it up : and then, on examining it, and
taking it to pieces, they found the whole cavity, from one end to
the other, nearly filled with a sparry incrustation, somewhat softer
than marble, but harder than alabaster*.

Strabo relates that the waters of Hierapolis, a city of Phrygia,
possessed this property -f. Pliny also notices similar waters J.
About fifteen miles from the city of Lucca, in Tuscany, is a spring,
•which arises from a mountain named Corsena; the water of which,
being made to pass through pipes, soon clogs them by an accretion
of stony matter.

* Pilosophical Transactions, vol. Ixviii. p. 241.

f Strabonis de Situ Orbis, lib. xiii. p. 600. Basilae, 1549.

J Lib. ii. cap. 103. Lib. xxxi. cap. i.

S65

The river Elsa, which arises between Sienna and Volaterra, sur-
rounds the bodies, which its current seizes, with a lapideous matter.
A similar property is possessed by the fountains of Aponus, near
Padua. The Silarus, a river not far distant fr6m Sorrento, is thus
spoken of by Silius :

Nunc Silarus, quos nutrit aquis, quos gurgite tradunt,
Duritiem lapidum mersis inolescere ramis.

Lib. viii.

In no part of the world, perhaps, do waters of this kind so much
abound as in Italy :* and in speaking of some of those which remain,
I shall take the opportunity of pointing out, on how very large a
scale this process of lapidefaction is sometimes performed

The beds and banks of such rivers, but particularly those basons
which receive their falling waters, suffer a continual accretion of
this stony matter: thus diminishing the grandeur and beauty of
these waterfalls. Thus the Tiverone, which was the prceceps Anio of
Horace, is described by Misson^ as now forming a large and plea-
sant sheet of water; but the fall, he says, is not high* : and a more
modern traveller, the Count Stolberg, observes, that it has lost much
of its natural beauty, because its bed has been deepened, partly,
he says, to guard against its wild torrents, and partly to form mill-
streams : but the more cogent reason, perhaps, for thus deepening
its bed, will appear, on attending to the following curious account,
given by Mercatus, of the lake Velino, the waters of which pos-
sessed this lapidifying property, in a high degree. The river Velino
passing, in its course, the town of Reate, belonging to the Umbri,
spread over the neighbouring widely-extended marshes, and formed
the lake Velino, now called Logo pi6 di Luco ; then, overcoming its
lofty banks, its waters were precipitated down a considerable water-

* Misson's Voyages, vol. ii. p. 65.

366

fall ; and afterwards joined those of the Nera. But so considerably
had the stony matter filled up this cataract, as to shut up the
waters, though accumulated to a great depth, in the marshes of
Reate: threatening to swallow up the delightful fields of^ the
Reatines, in a permanent lake. To prevent this mischief, the
Roman Senate sent M. Curius, who drew off the river from the
lake, and led it into the Nera, through a new channel, cut be-
tween the mountains. The nature of the waters, however, occa-
sioned the- advantages derived from this expedient to be but of
short duration: for the accumulating stone had began to narrow
the channel so much, that the inhabitants of Terni (Interamnates)
foresaw danger to themselves ; they therefore complained against
the Reatines, whose cause was defended by Cicero. After this,
during the reign of Tiberius, when the danger, became more evident,
and the Interamnates had reason to complain, that all their posses-
sions might be taken from them by a single flood, they petitioned,
that access might be given from the river to the lake, by a channel,
leading back from the side of the aqueduct, formed by Curius.
This was ordered, by Tiberius to be performed; but the peculiar
property of the water resisted the endeavours of Tiberius, as well
as those of Curius. The straight, as well as the reverted channel,
became filled with stone ; and the river, possessing itself of the
course, which it had at 'first, emptied itself into the lake, which,
not being able to retain it, there being now no opening, it again
overflowed the Reatine marshes. The Reatines were therefore an-
xious to open the cataract which had first of all been closed up
by the stone ; but this alarming the Interamni, great disputes arose,
which would have terminated in a war between these people, if the
Pope, Paul 111. had not interfered. He directed the old cataract
to be opened ; and, lest its immense force should terrify the Inter-
amnates, he moderated its violence by making three additional

openings, thus carrying off the waters by four outlets. All these
four cataracts of Velinus, Mercatus describes* as much narrower
than when first opened, and alarming the Reatines, lest the increas-
ing stone should cause the lake to extend its bounds, and destroy
their charming country.

Nor is their overflow the only inconvenience which waters, pos-
sessing this property, occasion to those who live in their neigh-
bourhood ; since the continual deposition, and increase of stony
matter, in evqry crevice, and in all loose soil, in which they pene-
trate, and on every spot on which they rest, is also a source of dis-
. appointment ; those parts being thus rendered stony and barren,
which had perhaps been allotted to corn and pasturage. Thus the
passage of the water having been interrupted in the subterranean
passages of the Claudian aqueduct of Rome, the water, soaking into
the bibulous earth, and penetrating into the surrounding cavities,
formed an extensive quarry of this tufaceous stone -f. At Matlock,
is a remarkable stratum of this kind, which, according to the ac-
count given by Dr. Dobson, in 1774 1, was 500 yards in length, in
several places ; nearly 100 yards in width; and, in the thickest parts,
from three to four yards in depth. The manner in which this great
body of stone had been produced, Dr. Dobson remarks, is easily
ascertained. Within the memory, he says, of some persons now
alive, the waters of Matlock were not appropriated to the purposes
either of bathing, or of drinking. They issued from near the bottom
of the hill, which lies to the west, immediately behind the present
houses, and ran, at random, down a declivity of about 100 yards,
to the river Derwent. In their course they formed large petrified
masses, intermingled with great quantities of petrified moss, nuts,
leaves, acorns, pieces of wood, and even trunks of trees. This

* Metallotheca Vaticana, p. 252.

t Roma Vetus ac Recens, &c. Auctore Alexandro Donate, p. 400, 1725.

$ Philosophical Transactions, vol. Ixiv.

368

stratum affords very curious and beautifully varied petrifactions ;
the moss, in particular, exhibits great varieties ; for it is evident,
that the moss has continued to vegetate, after the roots and lower
parts have been enveloped by the stony particles; and thus having
stretched itself to a considerable extent, it has, in some places, been
mixed and interwoven with other substances. In some parts, snails
have been arrested, in their sluggish walk, and locked Up in the
stony concrete. In others, the petrifying matter has shot in dif-
ferent directions, and formed an intricate kind of. net-work. In
others, again, there are large masses, which on being broken asun-
der, are found hollow, and their cavities ornamented with branches
of petrifactions, somewhat resembling coral, but of a light grey
colour, and generally of a rough and granulated surface.

About four or five leagues from Tauris, in a plain called Roomy,
there are several springs of water that petrify wood, and I have been
informed, Mr. Bell says, even reptiles, such as lizards. One thing
is certain, that, after a stagnation of this water, for a certain time,
there is a substance like marble found at the bottom, which the
Persians cut into any breadth, or length, at pleasure. I have seen
them, he says, of two or three inches thick. It is easily polished,
and is diaphanous, but not transparent. After sawing it into slabs,
they fix them for windows in their bagnios and private apart-
ments*.

Mons. de la Hire states -f , that a river which passes by the city of
Bakan, in the kingdom of Ava, has, for the space of ten leagues,
the property of petrifying wood ; and that large trees have been
seen, petrified to the top of the water, whilst the rest has remained
in the state of dried wood.

* A Journey to Ispahan, with an embassy from his Imperial Majesty, Peter the First,
to Kamhi, Emperor of China, in the year 1719, p. 82.
t Mem. de 1' Academic des Sciences, torn, x. p. 140

369

Count Stolberg informs us, that immediately beneath the an-
cient city wall of Posidonia, Pcestum, or Pesto, a rivulet runs, which
has a petrifying quality, that was remarked as early as Strabo: Its
banks are reedy, and some little hollow pillars bear evident marks
of being themselves petrified reeds *.

The waters of the Solfatara, or Logo di Bagni, abound with cal-
careous earth in solution. Cardinal D'Este had a Canal dug, by
which the waters of this lake should be carried into the Anio, to
prevent their overflowing : but it is remarked by Breislak f, that
the calcareous deposition is so abundant, that if they did not clean
it every three years, it would be closed up, notwithstanding its
width and .depth. Its waters, like those already mentioned, cover
with a calcareous crust the rushes, and other bodies it finds in its
course. When the calcareous crust, thus formed, is only a conge-
ries of fistula, or pipes, possessing but little substance, the name of
sj/ringite's has been applied to them; but when they are of a "thicker
substance, and have their openings almost closed, they are some-
times named osteocollce.

It appears to have been by the formation- of a curious species of
incrustation, in this manner, that nature pointed out to art the ap-
plication of this property of these waters. This species of incrusta-
tion, represented Plate III. Fig. 2. is termed Lapis Sarnius ; it is
formed of a tufaceous incrustation of very small t\yigs, leaves, &c.
but bearing on its surface most correct impressions of the leaves on
which it had been formed. These stones have been termed Sarnian,
from a river in Campania (Terra di Lavoro) of which tl>e poet thus
speaks :

* Travels through Germany, Switzerland, Italy, and Sicily, by Frederic Leopold
Count Stolberg, vol. ii. p. 112.

f Voyages Physiques et Lythclogiques dans, la Campanic, par Scipion Breislak, torn. ii.
p. 262.

VOL. i. SB

370

• Videos lapidescere Sarni
Caeruleo sub fonte alnum, filicisque maniplos,
Et palese intortos lento cum vimine culmos.

PONTANUS.

But this name has not been confined to those substances, which
have been thus formed, by the waters of the Sarnus alone, but it
has been applied, in Italy, at least, to all similar tufaceous incrusta-
tions and impressions, which have been formed by the waters of
other springs and rivers.

The property which these waters possess, of thus filling up the
beds and contracting the channels, through which they flow, proves,
as we have seen, the source of considerable inconvenience to those
wbo inhabit the neighbouring lands ; exposing them not only to the
dangers which proceed directly from the overflowing water ; but to
the evils resulting from the accumulated masses of stony matter.
How strange and inexplicable is it, that a regular operation of na-
ture, so constantly going on, should be pregnant with so much evil !
— This may naturally be expected to be the exclamation of some,
at the first view of the phenomena, here described. But a more
attentive consideration will make it known, that this extraordinary
process is in pefect agreement with that beautiful symmetry and
order, which evinces the works of nature -to be directed by con-
summate wisdom. By this process, the finer parts of the loose and
coarse lime-stones are brought up in a state of solution, from the
deep recesses of the earth, and deposited at the surface in a firm,
coherent mass — that which, from the nature of its composition, and
its situation, is comparatively useless to man, is, by a chemical ope-
ration of nature, changed to a substance of the greatest utility,;
and is even brought, by the powers of the same operation, from
inaccessible depths, and placed immediately before him : impelling
him to the employment of it, in various ways, for the multiplication
of his comforts ; and particularly prompting him to exchange the

371

clay-built, or wooden hovel, for a more durable and pleasant mansion.
Thus we see, man is driven by a predestined, and apparently cruel,
necessity, to the exercise of those powers, and the invention of those
arts, by which his happiness and welfare is promoted ; and is forced,
by a most salutary, but mysterious, influence to make his destined
advances in the progress of civilization.

Thus we find that almost all the houses in the neighbourhood of
Matlock, and in some other parts of England, are built of this
kind of stone, which is found exceedingly durable. The mountain
of Tivoli, formed by this species of calcareous deposition, has fur-
nished, time out of mind, the greatest part of the stones which
have been used at Rome. This stone is usually called Travertin, a
corruption of the word Tibertin. The front of St. Peter's Church is
built with it; and the Colosseum, according to Misson*, is covered
all over with it. Count Stolberg also observes, that its upper part is
formed of a light porous stone. Breislak says-f-, at the foot of the
mountain of Tivoli, where the Anio enters the plain which reaches
to Rome, are the quarries of Travertin. Independently, he says,
of the immense quarries, dug by the ancients, there are others of
such a vast extent, as will be sufficient to supply the demand of a
great number of ages.

Nor is this deposition, of stony matter confined to the surface,
since this petrifying process is likewise carried on. in immense ca-
verns, at some depth in the earth ; where immense quarries of stone
are thus formed, and laid up in store for man's future use. Through
the roofs of these caverns, the pellucid solution of carbonate of
lime filtrates, and deposits, from the moisture left of every falling
drop, the spar it contains : forming, by the growth of ages, innu-
merable stalactites, which depend, like icicles, from different parts

* Misson's Travels, vol. ii. p. 66.

t Voyages Physiques et Lythologiques dans la Campanie, par Scipion Breislak, torn. ii.
p. 262.

372

I

of the ceiling, in various sizes and forms. On the floors of these
caverns, also, the repeated drops as they fall, deposit their solid
matter in sta'lagmitic heaps ; which rising by the gradual, but con-
stant accretion of fresh matter, acquire frequently a considerable
degree of magnitude, and assume various fantastic forms. On every
part of the sides, also, the trickling drops deposit innumerable mi-
nute crystals i and here also, from the same source, numerous sta-
lactites become disposed in an arrangement, more approaching to
regularity.

The entrance to a cavern of this kind, is, jn general, by a narrow
opening, beset on every side by stirice, formed by the exuding spa-
those matter; -and which, if not interrupted in its accumulation,
would entirely close the opening. On passing this, and arriving at
the cave itself, the mind is almost overpowered by astonishment
at the novel scene. The ceiling appears to be supported by columns
of the most pleasing colour and elegant shapes, formed by the union
of opposite stalactites and stalagmites : whilst others are seen in
various degrees of approximation to each other, and assuming the
most strange and uncouth shapes. Some hang from the roof, in the
form of an inverted cone ; some spread out in branches, not much
unlike those of a chandelier ; whilst others form in slender and al-
most transparent tubes, reaching nearly to the bottom. From the
floor numerous rugged pyramids arise, intermingled with various
figures, to which fancy attributes some strange and unexpected re-
semblance, such as to altars, animals, trunks of trees, &c. The
ornaments on the sides render the effect on the mind, of this seeming
magic scenery, complete. The light of the torches employed in
these subterranean explorements is reflected in myriads of bril-
liant sparks, from the crystalline surface with which the walls are
covered; whilst globular excrescences of yellow spar give the ap-
pearance of balls of gold, projecting from a white, and sparkling
ground of diamonds. Frequently the slender stalactites, mentioned

as adhering to the walls, will be so arranged, as to resemble the
pipes of an organ ; and, on being struck by any hard substance,
will contribute to the delusion by sending forth a dull, bu.t ringing,
musical sound. The grotto of Antiparos ; the Baumannian cave in
the neighbourhood of Blankenberg ; the caves in the Hercynian
forest ; the grottoes of Arcy, in France ; of Chaumont, in- Nor-
mandy; those astonishing natural excavations in Derbyshire, and
various others, may be considered as so many laboratories in which
nature is discovered, in her deep and secret recesses, unintermittingly
employed, separating, from the rude materials, the finer species of
stone, and amassing it in vast and inexhaustible stores.

To ascertain the circumstances, on which the deposition of the
calcareous earth from different waters, immediately*depends, would
require a careful analysis of the separated matter, .of the waters,
from which the deposit is directly made, and of the different tribu-
tary streams ; as well as an examination of the strata through which
they pass, and the various circumstances under which they flow.
But, in this place, it will be sufficient to point out to your notice,
those properties of this earth, by which its solubility in water, and,
consequently, its precipitation, will be chiefly affected.

Lime, in its pure state, is soluble in about 700 times its weight
of water, at the temperature of 60°, and thus forms Common lime-
water; but if to this a small portion of carbonic acid be added, it
unites with the lime, forms a carbonate of lime, and precipitates in
an insoluble state. If, on the contrary, such a quantity of car-
bonic acid be added as will completely saturate the lime, it is again
rendered soluble in water; and it is thus that carbonate of lime,
held in. solution, by an excess of fixed air, not in actual combina-
tion with the lime, but contained in the water, and acting as a
menstruum, is commonly found in all waters *. A separation of

* Analysis of Mineral Waters, p. 1 5.

374

carbonate of lime from waters holding it in solution may therefore
result from two opposite causes ; an absorption of carbonic acid,
from the atmosphere, or for some subterranean source ; and the
loss of that part of it, which exists in excess, and which may be
driven off by heat, or forced into other combinations, by the com-
bined agency off different affinities. A farther investigation of the
circumstances on which these 'depositions depend, does not appear
to be necessary, it seeming to be sufficient to have ascertained that
water, saturated with carbonate of lime, is not only flowing over
various parts of the earth's surface, but is also transuding its sub-
stance in almost every direction. That it should therefore impreg-
nate with its earthy particles, any substance, which like bitumi-
nized wood, or Ay decaying organic substance, might be fitted to
receive it, appears to be highly probable ; and that calcareous fossil
wood may have been formed by such an impregnation, and under
such circumstances, every character which it possesses, eithr phy-
sical or chemical, serves to demonstrate.

Yours, &c.

LETTER XXXIX.

CALCAREOUS FOSSIL /WOOD.... WHERE FOUND. ...CALCAREOUS WOOD
OF OXFORDSHIRE. ...DORSETSHIRE.... SOMERSETSHIRE.... AN A LY-
SIS....MIXTURE OF SPAR AND BITUMEN. ...C ALC AREOUS WOOD
OF NEW SOUTH WALES. ...ALUMINOUS WOOD, &C.

AT has been said, that calcareous wood is found, in various parts
of the continent, and particularly in the neighbourhood of Arund-
see in Brandenberg ; near Joachimsthal, in Bohemia ; at Schem-

375

nitz, in Hungary ; and in several parts of Wirterriberg, Franconia,
Lower Saxony, £c. But from the very few specimens of this kind
of wood, which we obtain from the continent, and, indeed, from
their being so little dwelt on by the French and German writers on
fossils, it seems that they exist more plentifully in this- island, than
elsewhere. The specimens which are in most repute, for their
beauty and preservation, are those which are found in Dorsetshire,
in the neighbourhood of Charmouth ; in Somersetshire, particu-
larly in the neighbourhood of Bath ; handsome specimens have also
been found in Derbyshire, Dorsetshire, Oxfordshire, and in many
other counties of England.

The appearance of the wood, in this species of fossil wood, as
well as in the silicious, shows that the wood, which has been thus
petrified, existed previously, either in a dry and shivered, or in a
bituminous state. A specimen, from Oxfordshire, is figured in
Plate VI. Fig. 16. It is of a pale ash colour ; and the light and
fragile woody fibres may yet be seen very plainly, although much
broken, intersected, and separated by the crystallizations of the
calcareous spar, which has pervaded every part. The substance of
this fossil is rather tender; yielding sometimes, even to the force
of the fingers. Its gravity is of course considerably less than that
of silicious wood. Although the greater part, by far, of its bulk
is formed by the spathose matter, yet the form of the wood is tole-
rably well preserved ; the natural direction of the fibres of the wood
seeming to have directed, for the most part, the crystallizations
into striae, converging towards the centre of the wood, as may be
observed in its section, shown at Fig. 2. of the same Plate. Distinct
masses of crystallizations and veins of spar may frequently be ob-
served to penetrate its substance in various parts.

A specimen of the Charmouth fossil wood is represented in Plate
III. Fig. 9« The colour of this kind of fossil wood is darker than
the former, it being of a deep brown colour. It is harder than that

376

which has been just described, from its possessing hardly any
vacuities. The texture of the wood is very evident, and even
the knots of the wood are frequently perceptible : but, as in the
Bovey-coal, so in this fossil, the woody fibres are distorted in
various directions, in such a manner as could not have taken
place, if they had not been in some degree softened. The calca-
reous spar, which permeates the wood through every part, marks
it in many places with streaks of a beautiful pearly white,
formed by the deposition of the spar from its infiltrated solution ;
and when this happens to have been the case in a cavity rather
larger than the others, such an arrangement of the particles of the
carbonate of lime will sometimes take place, as is -observed in cavi-
ties large enough to allow of the formation of stalactites, and the
cavity will be found to be filled with striated or fibrous carbonates,
or alabaster. Thus, under one or the other of these forms, will the
carbonate of lime be found to fill every cavity and rift in the wood
which had been produced by the mechanical action of the water
in which it had lain, or by subsequent shrinking of the wood.

The calcareous fossil wood which is found in the neighbourhood
of Bath, and of which a specimen is depicted in Plate V ill. Fig. 4.
resembles very much in colour that of Charmouth ; but is harder,
and retains, still more perfectly, the form of the wood. In the par-
ticular specimen, described in the Plate, the spar so penetrates the
mass, as to accompany the fibres, in all their directions, in threads,
so minute as to be discovered, in many parts, only by tl^e aid of a
lens, of no small power. It is also pervaded through its whole
substance by a mass of spathose matter, about half an inch in width ;
and yet the fibres of the wood are nearly as evident, on the polished
surface, as if they had undergone no change.

Whilst inquiring -into the nature and origin of silicious fossil
wood, I ventured to attribute its formation, to the impregnation of
wood, chiefly, in different stages of bituminization, with silK,;<>«i-

37?

earth ; but was unable to adduce any direct, and positive, evidence,
in favour of this opinion, owing to the refractory nature of the
silex, which 'demanded such agents to effect its separation, as would
not fail to occasion a decomposition of the vegetable, or bituminous
matter, with which it was combined. In calcareous fossil wood,
which I suppose to differ from the former, merely in the nature of
the earth thus introduced, the same difficulty does not exist; since it
will yield to the action of less destructive agents, and will allow of
the complete separation of the superadded, from the original matter.
Thus, by the addition of the mineral acids in a state of dilution, it
might be expected that the carbonate of lime would be decomposed,
and that the interposed particles of earth might in this manner be re-
moved, leaving the vegetable or bituminous matter, in that state, in
which it existed, when its particles were first, perhaps some thousands
of years since, involved in this stony mass. The result of such an
experiment might also afford some elucidation of the question, re-
specting the formation of silicious wood; since if the original matter
could be plainly made out, in the case of calcareous fossil wood,
the inference would undoubtedly be admitted, that it was the same
in the silicious fossil wood, and that in both cases the lapidifying
change had been effected by impregnation, and not by substitution.

A piece of the light-coloured fossil wood of Oxfordshire, already
described, was immerged in nitric acid, diluted with about four
times its bulk of water; a considerable degree of effervescence en-
sued, which lasted several hours ; at the end of which time, the car-
bonate of lime being completely decomposed, the original matter
of the wood had fallen to the bottom, in the form of a dark, fine,
umber-coloured, flocculent sediment; the carbonate of lime having

o

been so thoroughly diffused between these light particles, as to have,
been their only bond of connection. A portion of this sediment,
after having been washed and dried, was placed on a red-hot iron,
when it directly inflamed, and was quickly consumed.
VOL. I. 3 c

3? 8

A piece of the Charmouth fossil wood being immerged, in similar
diluted nitric acid, a violent effervescence took place, during which
some light particles were detached ; and at the end of twelve hours>
the effervescence having ceased, the fluid was poured off, when a
dark brown, friable, but coherent mass, bearing every appearance
of bituminous wood, was found. This being repeatedly washed,
and afterwards dried, was exceedingly light and brittle, but still
retained the form and colour of bituminized wood. On being ap-
plied within an eighth of an inch of the flame of a candle, or of
any substance heated red-hot, it caught fire, and burnt like touch-
wood, without inflaming ; but., if brought into contact with the
flame, it yielded a white flame. The appearance it made, whilst
burning, from the spread of the fire through its substance, from its
phosphoric glow, and from its brilliant white lambent flame, resem-
bled very much that which is yielded by the burning of pyrophori.
In whichever way the combustion was directed, a strong bituminous
odour was experienced. A piece of the Bath fossil wood being ex-
posed to the same trials, furnished exactly the same results.

The residuum thus obtained from calcareous fossil wood, fur-
nishes us with considerable information, not only respecting the
state in which it existed, previous to its petrifaction, but also in
regard to the mode in which this process has been accomplished.
After considering its properties, we must surely conclude, not that
— the more fixed, earthy parts, deprived of their oily, and volatile mat-
ters, had been combined with the lapidiftc matter; nor that — a SUB-
STITUTION of stony, in the place of organized matter* had taken,
place; nor that — the lapidifying matter had been injected, whilst
melted by heat, into the interstices of the combustible substance : but,
we must rather infer, from the high degree of combustibility, and
even of inflammability, possessed by this residuum; and by the
form it retains, that the original woody substance, previous to its
envelopement with stony matter, underwent a change by which it

379

became much more susceptible of the action of fire ; or, in a word,
acquired a bituminous nature : in which state it now presents itself
on being freed from its stony impregnation.

One circumstance, however, was wanting to render the analogy
between silicious and calcareous wood complete. In that species
of silicious wood, which has been distinguished by the term opa-
lized wood, appearances were observable, which seemed to warrant
the conclusion, that some of the bituminous wood had existed, at
the time of its impregnation with silex, in a softened, and, perhaps,
fluid bituminous state; and that the waxy lustre, which this species
of wood displays, proceeded from the intimate union of the silex
and bitumen, whilst each was in a fluid state : but no analogous
appearance to this had offered itself, to my observation, in any
specimen of calcareous wood. It happened, however, that, a few
days before this sheet was sent to the press, I met with a piece of
calcareous spar, imbedded in blue lime-stone, which, at its fracture,
displayed somewhat of the resinous lustre; and on its polished
surface, exhibited a beautifully clouded appearance, resembling
tortoiseshell, yielding, in fact, exactly such an appearance, as might
be expected, from the intermixture of petroleum and spar. By the
aid of a magnifying glass, somewhat of a fibrous texture, like that
of wood, was observable in the lighter-coloured parts, but not in
the least in the dark, apparently bituminous parts, which had just
so much transparency as to allow the transmission of light at its
edges. A small portion of this spathose matter, about 50 grains,
was added to an ounce and an half of water slightly acidulated with
nitric acid. During the effervescence, several small fragments, evi-
dently of bituminous wood, were detached ; and, on the subsiding
of the effervescence, these sunk to the bottom, leaving the fluid still
turbid, and of a dark brown colour: but, in about twelve hours,
the liquid became clear ; the less completely changed wood sunk to
the bottom, and a light bituminous matter swam at the top. That

380

calcareous spar may owe its colour, in some instances, to bitumen,
must therefore be admitted : nor do I in the least doubt but inves-
tigation will discover, that the influence of bitumen is much more
extended, among the class of calcareous stones, than has been
hitherto supposed.

The appearance which the above-mentioned fossil wood from
Oxfordshire yielded, previous to its exposure to the action of the
acid, was such as to lead me to suppose that it must have existed,
in a dry and withered state, at the time of its lapideous impregna-
tion, it being of a very pale colour, nearly resembling that of de-
cayed wood. But, on the removal of the stony matter, by the
action of the acid, it resumed the dark brown colour of bituminous
wood, which it retained, after it had been dried by the fire. The
light colour, which had thus deceived me, evidently proceeded from
the abundance of the white, spathose matter, with which it had
been penetrated ; and which had been in so considerable a propor-
tion, that, on its removal by the acid, the vegetable or bituminous
matter no longer held together, but subsided in a flocculent sedi-
ment to the bottom of the vessel.

This kind of fossil wood is frequently found inclosed within the
solid lime-stone ; and it happens most frequently, that when suffi-
cient carbonate, in solution, has not percolated through the coarser
carbonate, or lime-stone, to impregnate the whole of the inclosed
wood, the latter remains soft and yielding, and exactly like bitu-
minious wood ; and what carbonate has entered, is formed into cry-
stalline septa, which, by intersecting each other, necessarily divide
the inclosed wood into small polygons: the whole yielding an ap-
pearance, which would not be badly represented by Fig. 5. in
Plate I. only substituting the brown bituminous wood, for the jet:
nor would a very dissimilar idea be formed of it, by conceiving its
divisions to resemble those of the Septarium, Ludus Helraontii, or
Waxen Vein.

381

It would be improper, whilst treating of calcareous petrifactions
of vegetables, to omit noticing those of Preservation Island, in New
South Wales. These are thus described by Mr Collins, in the sen.. id
volume of his account of this colony. "Amid a patch of naked
sand, upon one of the highest parts of the Island, at not less than
100 feet above the level of the sea* within the limits of- a few hun-
dred yards square, were, lying scattered about, a number of short
broken branches of old dead trees, of from one to three inches in
diameter, and seemingly of a kind similar to the large brush wood.
Amid these broken branches were seen sticking up several white stony
stumps, of sizes ranging between the above diameters, and in height
from a foot to a foot and a half. Their peculiar form, together with
a number of prongs of their own quality y projecting in different
directions from around their base, and entering the ground in the
manner of roots, presented themselves to the mind of an observer,
with a striking resemblance to the stumps and roots of small trees.
These were extremely brittle, the slightest blow with a stick, or with
each other, being sufficient to break them short off; and when taken
into the hand, many of them broke into pieces with their own
weight. On being broken transversely, it was immediately seen, that
they were divisible into interior or central, and exterior or cortical.
The exterior part, which in different specimens occupied various
proportions of the whole, resembled a fine white and soft grit-stone ;
but acids being applied, shewed it to be combined with a consi-
derable portion of calcareous matter. The interior or central part
was always circular, but seldom found of the same diameter, or of
the same cemposition, on any two stumps. In some the calcareous
and sandy matter had taken such entire possession, that every frag-
ment of the wood was completely obliterated ; but yet a faint cen-
tral ring remained. In others was a centre of chalk, beautifully
white, that crumbled between the fingers to the finest powder:
some consisted of chalk and brown earth, in various quantities ;

382

and some others had retained a few frail portions of their woody
fibres, the spaces between which were filled up with chalky earth."
Mr. Bass, who acted as Surgeon on board the Reliance, and from
whose accurate examination the above account is taken, was told,
from good authority, that when the trees were in a complete state,
the diameter of the dead wood of the stem, that rose immediately
from the stony part, was equal to the diameter of that part ; and
also that a living leaf was seen upon the upper branches of one of
them. Mr. Bass was induced to place these altered vegetable subr
stances amongst petrifactions, although, he says, no strict analogy
could be discovered between them and the subjects usually met
with of this kind : this gentleman acknowledging, at the same time,
the great difficulty of accounting for this wonderful change which
had taken place in the lower parts of the stems of these trees.

If this ingenious and intelligent observer found himself incapable
of explaining the mode in which this change had been accomplished,
it is not to be expected that even the attempt should be made by
one not possessing the advantage of examining the substances them-
selves, nor of ascertaining their relative situation with the surround-
ing substances.

In the Philosophical Transactions is the description of a pheno-
menon which seems to bear some slight resemblance to that which
has been just described, and which also is not capable of being
explained, by any of those laws on which the various processes of
petrifaction appear to depend. It is thus related :

" In a close of Mr. Purefoy, near his house, called Wadley, a mile
from Farringdoji, in Berks, there grows an elm, which hath now lost
the top, and is grown hollow, containing near a ton of timber. From
the but of the same tree, one of the spreading claws, having been
formerly cut off with an axe ; that part of the but, from whence the
same was severed, being about If foot above ground, and inward
within the trunk of the tree, hath contracted, a petrified crust, about

383

the thickness of a shilling, all over the woody part with the bark ;
the marks of the axe also remaining very conspicuous, with this
petrified crust upon it. By what means it should thus happen
cannot well be conceived, in regard there is no water near it, the
part above the ground, and out of the weather; the tree yet grow-
ing ; unless being cut at some season, when the sap was flowing, the
oozing of the sap might become petrified by the air, and the tree
grow rotten and hollow inward since that time ; which how long
since is not known.

" A piece of that part cut was presented, together with this ac-
count, to the Royal Society, for their repository *."

Aluminous fossil wood is mentioned by several authors : Mr. Walch
describes it as being of a brown colour, of a light weight, and pos-
sessing sufficient of its vegetable structure to demonstrate its origin ;
he also relates, that when considerable quantities of it are exposed
to the air, that it will take fire spontaneously. Besides being found
in various parts of England, it is found in considerable quantities
at Commadau and Altsattel, in Bohemia : near Hainfield, in Lower
Austria; at Weisner, in Hesse; and near Duben, in Saxony.

The spontaneous inflammation of this species of wood, and the
use to which it is applied, the fabrication of alum, manifest that it
is a pyritous wood blended with clay. The chief component parts
of alum (the sulphate of alumine) are the acid of sulphur and the
earth, alumine; the former of which is derived from the sulphur
contained in the pyrites ; and the latter from the clay, of which it
constitutes by far the greatest part.

What other earths enter into the composition of fossil woods,
and in what proportion, must be determined by future analyses.

Philosophical Transactions, No. 19, Nov. 1666.

384

LETTER XL.

METALLIC FOSSIL - WOOD.. ..BOG IRON ORE.. ..FOSSIL WOOD, IM-
PREGNATED WITH IRON. ...WITH COPPER, &C.

BESIDES the pyritous fossil woods, already treated of, there exists
a great variety of metallized fossil woods the peculiarities of which
we shall now endeavour to ascertain ; but which could not have
been so well done, until the influence of bituminization in the pe-
trifaction of vegetables had been displayed.

As iron is the metal which is most generally diffused in the earth,
so it is also most frequently found in combination with fossil wood.
The most remarkable specimens of this kind of wood have been
found in Siberia, and in various parts of Germany. In the year
1710, a wonderful metamorphosis of a tree into iron ore, to use the
words of the author*, was discovered in the neighbourhood of
Solms Laubac. In digging a well, the workmen first found, at the
depth of a few feet, an urn, from which, and some other circum-
stances, it was supposed to have been a spot on which the remains
of the dead had been consumed. When the diggers had reached
the depth of 70 feet, their progress was checked by a vast impene-
trable mass, which appeared to be the trunk and branches of a large
tree. Finding this mass to resist their hatchets, and other instru-
ments, they proceeded to remove this impediment to their labours
by force; breaking, but with great difficulty, the metallized tree
into fragments, which they threw about, without any further notice.
Chance, however, having brought some of these fragments to the

* J. J. Liehnecht, Discursus de Diluvio Magno, page 206. 1714,

notice of Liebnecht, he subjected them to the necessary examina-
tion and clearly ascertained, that, although the texture was indu-
bitably that of wood, the substance was an ere of iron. In tLe
iron mines of Montrouge, beyond Martis-see, the greatest quantity
of the iron ore, which is dug from the depth of from seven to eight
toises, is said to be wood of the birch, and of the beech tree, changed
to iron, A similar ore is also dug at Orbisau, in Bohemia ; and very
handsome specimens of this kind of wood are found, according to
Bertrand, in the canton of Berne, in Switzerland. Near the lake
Langelmo, in Finland, parts of trees are said to be found, which
appear to have suffered a conversion into iron.

Almost every specimen of wood, mineralized by iron, except those
of the pyritous kind, seem to owe their change to the introduction
of particles of the red oxide of iron, or that oxide which precipi-
tates with an excess of its base, from a solution of the oxy-sulphate
of iron. What is here said, will be better understood, by calling to
your recollection a phenomenon, which occurs in the neighbour-
hood of springs impregnated with iron, held in solution in the
sulphuric acid. In every little puddle or swamp, in which this kind
of mineral water is collected, a yellow precipitate is discoverable,
which has been deposited from a yellow crust which is continually
forming on the surface of the water. On a similar deposition of
oxide, in situations, which, from their proximity to the surface ; or
from rifts in the superincumbent strata, which admit a communication
with the external air, the formation of these various kinds of speci-
mens depends. An egress is here allowed to the separated gaseous
matter, on the confinement of which the formation of pyrites and
coal, &c. seem to depend ; a constant separation of red oxide, or of
oxy-carbonated iron, goes on, which fills every interstice of the
loose bituminous wood; whilst the dissolved sulphated iron, per-
meating every more solid part, cannot but be affected by the strong
reductive powers, possessed by those principles of which the bitumen

VOL. I. 3D

S86

is constituted, and will be likely to deposit, in its substance, an
oxide, so nearly at its minimum of oxidation, as to approach nigh
to the hardness, gravity, and lustre of a metal. Such, indeed, ap-
pears to be the constitution of those specimens of ferruginous wood
to which I here allude. That part which was originally ligneous
appears to have become the most solid and metallic, whilst the
cavities appear to have been filled by a rust-like precipitate.
Among the boggy iron ores, are frequently found specimens which
illustrate the manner, in which this kind of metallized wood is
formed ; and also show that it has been by an operation carried on
near the surface. In these, which are often in large masses, broken
twigs of trees, grass, and other vegetable matters, are found, consi-
derably changed, and indurated, and connected together by a fine
yellow, or yellowish brown, oxide of iron. But the following account,
from an intelligent observer, will serve to give you a more correct idea
of the^effects resulting from this important natural process.

Mr. Tooke, remarks, that one of the principal curiosities, among
the mountains of Russian Lapland is in the martial waters of Us-
sona, Muun-ozero, &c. Here are seen, he says, a vast quantity of
stems, branches, twigs, leaves, and roots of birch trees, and other
exuviae of vegetables, entirely mineralized by iron, with the diverse
texture of the rotten wood plainly visible ; in which mineralizations
the tender white rind, known to be in the highest degree incorrupt-
ible, is preserved quite in its natural appearance ; the soil is changed
into a rich ferruginous earth, and the grassy sod into iron ore. The
like transmutations are seen in all the low spots and pits that incline
towards the Muun Lake, but particularly near the Martial Waters,
and over against the village Buijova. Here lies the iron ore in a
wide extended valley, forested apart with birch-trees, and with
gently-rising hills on both sides. In this valley, though not in its
deepest bottom, issue the Martial Springs, which, in 1716, by com-
mand of Peter I. were fitted with accommodations for public use.

387

The well is sunk about three archines and a half below the surface,
in a hole in the ground, consisting of parts of roots both of trees
and herbs (which are partly mineralized), and intermingFed with
flakes of stones, then an archine and an half in a clayey kind of
stone, mixed with a great quantity of sulphur pyrites. In the deep
points of the valley, under the forementioned, there is a layer of
vitriolic earth, which is a mixture of iron earth and swampy iron
ore (bog ore). It is easily got, and is then taken to the vitriol
works, and there boiled *.

According to the degree of change which the vegetable matter
has undergone, and the quantity of metal introduced, must of course
its gravity vary ; hence the range of variation of gravity in different
specimens of fossil iron wood is very great. The specimens in
which the change has been considerable, will in general be found
to be of pretty high specific gravity. These are chiefly formed of
a brown rust-like metallic substance, sometimes marked by spots
of a red colour, approaching to a crimson; the form and texture
of the mass readily leading to a recognition of its original mode
of existence. By far the greater part of some specimens, is evi-
dently composed of pyrites, the rust-like substance appearing only
on the surface ; but in these, there is great reason to suppose, that
this covering has proceeded from a partial decomposition during
exposure to the air.

It is necessary to observe, that, independent of those specimens,
which, from the very large proportion of iron which they contain,
deserve to be distinguished as metallic, there is scarcely any speci-
men of fossil wood on which the indurating effects of iron does not
appear to have been exerted. Jt is evident, that to the different
precipitates of this metal, may be attributed many of the various
beautiful colours which the several specimens of silicious fossil
wood are found to display.

* View of the Russian Empire, by WUliam Tooke, Esq. vol. i. p. 86,

388

Among the more beautiful of the fossil woods are those which
owe their metallization to copper; the finest specimens of which
are found in Siberia. The most accurate account of this species of
fossil wood is furnished by M. TAbbe Chappe 'd'Auteroche, who
travelled, in the year 176*1, into Siberia, where it is found in very
considerable quantities, in the copper mines of the Ryphean moun-
tains, and in the neighbourhood of Cazan. He describes different
kinds of specimens. The first kind he speaks of as copper mine-
ralized in sand and wood. In this mine he observes that blend,
which he at first took for iron, is distinguishable, mixed with wood,
sand, and copper. Those parts which contain the blend and the
sandy part, form a very hard and compact stone ; but the vegetable
parts which it contains are so friable, as to be very easily detached ;
the copper being discoverable in large spots of a beautiful grass-
green colour. The wood is black, and resembles charcoal, whose
parts are united together by some tenacious matter. The copper is
crystallized in many parts of the vegetable substance ; its crystalli-
zations forming small cells. These are sometimes of a clear dark
or blackish green colour, and possess so much brilliancy, as to give
the idea of vitreous crystallizations. The copper is blended through-
out with a calcareous earth. The mine from which this mineral
was obtained is to the north of Souxson.

Another mine, to the south of Souxson, he found differed from
the one just mentioned only in being more rich, and in the sand
and the blend being in a less quantity. In this mine were many
parts of an azure blue, sometimes in layers, and frequently in
patches. Speaking of copper mineralized in wood, he says, It may
be discovered, by the specimen which I brought, that it belonged
to a tree which was at least a foot in diameter. The internal part
is reduced almost to charcoal, being very friable, although the parts
are held together by a tenacious matter. The copper is sometimes
crystallized in little cells, resembling those of an honey-comb ; but

389

these crystallizations are, in general, only among those filaments
of wood which have entirely lost their original nature. The bark
is distinguishable, being about four lines in thickpess. There are
two layers, one of which is of an azure blue, the other of a pale
green, approaching to verdigris. This wood was taken from the
mines in the neighbourhood of Souxsons. Mons. D'Auteroche was
informed, on the spot, that they sometimes found, in the strata of
these mines, entire trees. The specimens he brought home, he took
from a collection which occupied the greatest part of a room, which
was more than twenty feet long. This wood, he observes, contains
more or less copper, according to the places where it has been
found ; and displayed various appearances, with respect to colour,
but always possesses either green, or azure blue*.

An examination of the several specimens of fossil copper wood,
which I am happy in possessing, shows that the impregnation is
made by a carbonate of copper, which appears in several places in
its most beautiful form, that of malachite. The brilliance of their
colours, the completeness of the transmutation, and the perfect
preservation of their original forms, place these specimens among
the most beautiful and interesting of the vegetable secondary fossils.
One small specimen, described at Fig. 19 in Plate VI. is highly inte-
resting, on another account. On its surface, the charred wood, and
spots of malachite, are discernible, in several parts, whilst a trans-
verse section shows its substance is formed of copper pyrites, of a
metallic lustre, displaying, by the striae and circles with which it is
intersected, an indisputable ligneous structure.

Whilst speaking of the impregnations of fossil wood with iron, I
spoke of those, which, although evidently containing that metal,
did not hold it in that proportion as to admit them to be distin-
guished by the epithet metallic. A specimen of fossil wood, which

* Voyage en Siberie, en 1761, par M. 1'Abbe Chappe d'Auteroche. tome i. 2* partie,
p. 671.

390

I have lately obtained, yields a beautiful instance of this sub-im-
pregnation with copper. The ligneous form and texture, with even
the knots, are perfect. The colour in some parts differs but very
little from that of decayed wood, whilst the central part demon-
strates the strongest marks of its having undergone the bituminous
fermentation ; and the surface, tinged, more or less, of a greenish
hue, is marked by a few spots of malachite : the whole demonstrat-
ing, that an impregnation, with a solution of carbonate of copper,
had taken place, and had arrested the progress of the bituininizat-
ing process.

The combination of the other metals with fossil wood is not very
frequent. Some authors, and particularly Volkman, have spoken
of wood impregnated with silver. That this may have been the
case is by no means improbable ; at the same time, it is not to be
positively concluded, that the specimens, of which they speak, were
impregnated with this metal ; since it is not said that they had been
submitted to any chemical test ; and the brilliance of some pyrites
is such, that, although they do not contain the least particle of
silver, they frequently exhibit the splendour, and the whiteness of
that metal.

The respectable author of Outlines of an Attempt to establish a
Knowledge of extraneous Fossils on scientific Principles, and of Petri-
Jlcata Derbiensiat informs us in the former of these works, p. 150,
that he has seen specimens of fossil wood, thoroughly impregnated
with lead, or rather galena. A specimen is now before me, from Lord
Bute's Museum, which is evidently thus impregnated.

Yours, &c.

391

LETTER XLI.

VARIETY OF PETRIFIED WOODS. ...PROCEEDING FROM ORIGINAL
NATURAL DIFFERENCE. ...FROM THE LABOURS OF MAN.

1 HE resemblance between the recent and fossil woods is some-
times very close, with respect to colour. The bituminous willow,
found by Capt. Perry, near Dagenham-breach, he describes, as hav-
ing suffered little or no alteration in its colour; and, in a specimen
resembling mahogany, and in various others, now before me, there
appears to be the strongest reason for supposing, that, from the
absence of certain mineral or saline 'agents, the bitumen has retained
the colour of the vegetable substance, to which it was indebted for
its origin.

So perfectly do the masses of petrified wood sometimes retain
the characters which belonged to them in a recent state, that it
frequently happens that, although so considerably changed in their
naturr, it is not difficult to determine to what species of wood the
petrified mass originally belonged. Thus, in Plate II. Fig. 4, and
Fig. 5, is a specimen which bears an exact resemblance to a piece
of deal, which, having split at one end, has had the rifts, thereby
occasioned, filled up by a dark coloured bitumen, as is depicted in
Fig. 4 ; and which, as is shown in the section of the same piece, at
Fig. 5, has insinuated itself to a considerable depth into the sub-
stance of the wood. Volkman describes a similar specimen, as
having a black crust, like resin or pitch ; and which he supposes to
have been the resin of the fir or pine ; which had been caused thus
to exude, by the influence of subterranean heat. The "fir, which in
a petrified state is known by the terms Elatites, Peucites, and Li-

392

thoxylon Abietis, is said to be found less frequently in a petrified
state than many other trees ; at the same time that it has been
found in a bituminous state, much more frequently, than any
other. But the supposed frequency of its occurrence, in a bitumi-
nous state, is very likely to exceed the fact ; since the high degree
of inflammability, which bituminous woods possess, has led to the
suspicion, that all such woods, especially if their fibres ran straight,
were of the fir or pine kind ; their inflammabilitybei ng attributed
to the resin, or turpentine, which they were supposed to contain.

That they are frequently found in subterranean situations, in this
island, is indubitable. Dr. Leigh, speaking of the subterranean
trees found in several of the morasses in Lancashire, says *, " Not
only fir-stocks, but fir-apples, are likewise found in these morasses ;
and these, I hope, gentlemen will allow me could not belong to
any other tree, but to the fir : besides, the grain of the wood, and
the turpentine which upon burning drops from it, sufficiently de-
monstrate it to be really fir/'

Mr. Daines Barrington informs us, that he happened to see,
near Loch Rannoch, and in other parts of the highlands of Scot-
land, subterraneous firs which had been lately dug up. On cutting
them he found that they smelt strongly resinous, and he concluded
that they were firs, the grain of the wood further warranting this
opinion. The poor people, he observes, in those parts, use small
pieces of this wood, instead of candles. He, therefore, thinks that
there is little doubt that the fir was formerly an indigenous tree,
ki the northern parts of this island. Dr. Plot argues, that Cresar,
not having seen the northern parts of this island, where the pines
most probably grew, might easily be mistaken in that, as well
as wi¥h respect to the beech which he asserts was not in this
island, though the contrary has been found to be the fact. Whilst

* The Natural History of Lancashire, Cheshire, &c. by Charles Leigh, M, D, 1700, p, 59,

393

some have relied on Caesar's account, and have believed that at the
time of his visiting this island no fir-trees grew here, others have
supposed that they have been subverted, with the vast forests,
which were filled by the Roman soldiery ; and others report that
the remains of considerable forests of this tree have been seen
within the memory of man. But their subversion, most probably,
took place, at an epoch much more distant than that of the in-
vasion of this island by Julius Caesar.

A specimen of the petrified larch-tree (Laricites), from Mount
Krappe, in Hungary, is represented at Plate II. Fig 6., purchased
by Mr. Strange, from the Butean collection. Plate II. Fig. 8. repre-
sents a specimen of petrified hazel (Corylites), described, in the
Butean catalogue, as from the Kiesengeberg in Bohemia. The
petrified oak (Dryites) is said to be very frequently found ; it pos-
sesses a darker hue than the recent wood : a specimen, from the
neighbourhood of Vienna, bears strong characters of its original
state. The same observation applies to a specimen of the ash
(Melites) ; of the petrified alder (Chtrites), from Bohemia; and
of the box-tree (Bucites), also from Bohemia. The fossil wood
of the beech-tree (Onytites Syssites, °vel PhcgitesJ, of the laurel
(Daphnites), of the sandal-tree (Sandalites), of the willow (Sali-»
cites), of the mulberry-tree (Moricites), of the vine (Vitites), and
several others, have been described by different authors. But ima-
gination, in many instances, has so much assisted conjecture, re-
specting the kind of tree from which the fossil wood has originated,
that opinions respecting this circumstance should be received with
great caution; since very frequently the supposed resemblance is
founded on colour, and on direction of fibres, which may have un-
dergone considerable changes, and have even owed those particular
appearances, to the influence of circumstances dependent on a sub-
terranean situation. Whilst in some their vague and indistinct marks
are insufficient to allow of any opinion being adopted, respecting

VOL. i. 3 E

394

their primitive form ; in others, appearances offer themselves dissi-
milar to those of any known recent tree. The specimen at PL II.
Fig. 3. has been supposed, by some, to be of this kind ; whilst
others have supposed it, from its large pores, to have belonged to
some tree allied to the cabbage-tree. , The petrified wood of the
linden-tree (Philyrites) is said to possess generally a clear white
hue. Mr. Walch describes a white petrified wood found in Hungary,
which he supposes may have been of this tree ; but he says, that it
contains a stony substance, resembling a resin ; but which it cannot,
however, have been, since this tree yields no resin ; nor does resin,
although it hardens very readily, ever petrify. Besides, he remarks,
that it exceeds in quantity the remaining ligneous substance, and
manifests no mark of its being of a resinous nature, even when ex-
posed to the fire. He therefore concludes this matter must be of
the nature of spar, approaching to horn-stone; but which, like all
spar, does not give sparks with the steel. The substance here de-
scribed, was doubtless similar to that which has been before noticed,
as having been described by Mr. Walch, and as most probably
being a variety of the pitch-stone or serni-opal ; and, perhaps, a
combination of clear bitumen and silex. In a most beautiful spe-
cimen of fossil wood, of this kind, lately obtained from the collec-
tion of Mr. Forster, and which is more than a foot in length, and
a foot and a half in circumference, almost the whole of its substance
is formed of a semi-opaline substance, possessing the clear white
hue, mentioned by Mr. Walch, mingled with a dark brown semi-
pellucid pitch-stone : the surface only presenting the real appear-
ance of wood, and that in a withered shivery state, but yet impreg-
nated with silex.

Those substances which, though now in a petrified state, are sup-
posed to have derived their forms from the art of man, previous to
their undergoing the change from wood to stone, will be examined
with propriety, in this place, whilst considering the varieties which

395

occur, in petrified ligneous substances. The instances which have
been given of any fossil substances which had derived their form
from the labours of the inhabitants of the world, at any distant
period, are remarkably few, and do, indeed, all appear under cir-
cumstances which render the actual existence of such petrifactions
highly problematical.

The substances which have been most frequently mentioned, as
being of this description, are those which bear the form of logs,
billets, posts, and planks. But, surely, when it is considered, that
a rude resemblance may have been frequently sufficient to have
given rise to this opinion, and that wood, long exposed to the
weather, to alternate sunshine and wet, to agitation in water, and
afterwards buried by some violent convulsion, must be broken into
a great variety of forms, it is not at all improbable, that it should,
in some instances, assume an appearance, that may lead to the
suspicion of its having been subjected to the operations of art.
The same observation must apply to many of those substances
which have been supposed to have been stakes, posts, and piles,
which have been driven in the beds of rivers, &c. Of this descrip-
tion are the pieces of wood which have been frequently dragged
up from the bottom of the Thames, and which have been supposed
to have been placed there by the soldiers of Julius Caesar. One of
these was in the possession of the late Duchess of Portland, and
was purchased at her sale, for nine guineas, by the late John Hun-
ter, Esq. and is in the matchless museum, which, by the death of
that gentleman, is now in possession of the Royal College of Sur-
geons of this city. An examination of thifrbody tends to confirm
my suspicion, that substances of this kind do not owe any thing of
their forms to the labours of the Roman soldiers. This piece of
wood, about three feet in length, the surface of which is broken
into flakes, by drying, has exactly the colour, and general appear-
ance, of bituminous wood. Now from the observations, already

396

noticed of Capt. John Perry, made during his labours, so ingeni-
ously adapted to the stopping of Dagenham-breach, it is evident,
that the Thames intersects a vast bed of bituminous wood (moor-
log) ; pieces of which must be perpetually separating from the
banks of the river, and falling to its bottom ; and which, being re-
peatedly dragged up, have been supposed to have been planted
there, for the purpose of facilitating the Roman army in fording
this river. Indeed, wherever similar pieces of wood have been thus
found, in rivers, &c. near to which history informs us Julius Caesar
has ever been, the much altered appearance of the wood seems to

x *

have led to the attributing of it to the labours of that distant pe-
riod. Thus it is related, by Mr. Swinburne, that " The workmen,
in clearing the channel of Brindisi, drew up many of the piles, that
were driven in by Caesar. They are small oaks, stripped of their
bark, and still as fresh as if they had been cut only a month,
though buried, above eighteen centuries, seven feet under the sand*/3
But a later, and equally intelligent, observer remarks, that, " Dur-
ing the civil wars, Caesar ruined the haven of Brundusium, by cast-
ing up dams, and sinking vessels. He says nothing of staking it
up; neither do I think that there is any good ground for the opi-
nion that the oak piles, which were found there, were of Caesar's
driving-)-." With respect to the partial petrifaction of one of the
timbers belonging to Trajan's bridge over the Danube, already men-
tioned, there are, I acknowledge, certain circumstances in the rela-
tion respecting it, which render a more particular account necessary
before it should be regarded as a true petrifaction. The Abbe Re-
villas relates, that the handles of hammers and of hatchets have
been found in a petrified state J. Agricola also states, that in an

* Travels in the Two Sicilies, by H. Swinburne, Esq. vol. ii. p. 301.
t Travels of Count Stolberg, vol. ii. p. 162.

J Ragionamenti della Filosofia Pastorale, in Memoria sopra la Fisica et Storia Natu-
rate di diversi Valentuomini, torn. i. p.l 12.

397

old mine, were formerly found several buckets, and other wooden
vessels, which were changed into stone. That these substances
might, in these situations, acquire a certain degree of induration
from the impregnation with various metallic substances, but parti-
cularly with iron, is more probable than that they should have thus
become really petrified. The influence of iron in thus forming an
apparent petrifaction, is rendered sufficiently evident by the follow-
ing account, by Mr. Edward King*.

" In the year 1745, the Fox man of war was unfortunately stranded
on the east coast of Lothian, in Scotland, and there went to pieces ;
and the wreck remained about three and thirty years under water:
but this last year a violent storm from the north-east laid a part of
it bare; and several masses, consisting of iron, ropes, and balls,
were found on the sands near the place, covered over with a very
hard ochry substance, of the colour of iron, which adhered thereto
so strongly, that it required great force to detach it from the frag-
ments of the wreck. And, upon examrnation, this substance ap-
peared to be sand, concreted and hardened into a kind of stone/' —
The specimen which was laid before the Society, " contained a piece
of rope, adjoining to some iron ring, and probably had been tied
thereto. The substance of the rope was very little altered ; but the
sand was so concreted round it, as to be as hard as a bit of rock,
and retained very perfectly impressions of parts of the ring, just in
the same manner as impressions of extraneous fossil bodies are often
found in various kinds of strata.

" Now, considering these circumstances," Mr. King says, " we
may fairly conclude, in the first place, that there is on the coasts
of this island, a continual progressive induration of masses of sand,
and other matter, at the bottom of the ocean, somewhat in the
same manner as there is at the bottom of the Adriatic sea, according
to the account given by Dr. Donati.

* Philosophical Transactions, vol. Ixxix. part i. p. 35.

398

" In the next place (which is what more particularly deserves our
attention on this occasion), it should seem, that iron, and the solu-
tions of iron, contribute very much to hasten and promote the pro-
gress of the concretion and induration of stone, whenever they meet
and are united with those cementing crystalline particles, which
there is reason to believe are the more immediate cause of the
consolidation of all stones and marbles whatsoever, and which do
very much abound in sea- water."

The same conclusion, he also thinks, may be drawn from another
incrustation. " Some fishermen, sweeping for anchors in the Gull-
stream (a part of the sea near the Downs), drew up a very curious
old swivel gun, near eight feet in length. The barrel of the gun,
which was about five feet long, was of brass; but the handle,
whereby it was to be turned or traversed, which was about three
feet in length, and also the swivel and pivot on which it turned,
were of iron ; and all round these latter, and especially about the
swivel and pivot, were formed exceeding hard incrustations of sand,
converted into a kind of stone, of an exceeding strong texture and
firmness: whereas round the barrel of the gun, except where it was
near adjoining to the iron, there were no such incrustations at all.
The incrustation round the iron part of this gun was also the more
deserving of attention, because it enclosed within it, and also held
fast adhering to it on the outside, a number of shells and coralline,
just in the same manner as they are often found in a fossil state;
much resembling in colour- and appearance some of the masses of
fossil bodies found near Chippenharn, in Wiltshire. — It is to be ob-
served, notwithstanding the iron was, by some means or other, the
cause of this induration, it was very little dissolved, although the
gun must have remained in the sea above 200 years, and probably
a good deal longer.

" Dr. Fothergill, on passing through the streets of London in his
walks, before the sign-irons were taken down, perceived that,

399

on the broad stone pavements, whenever he came just under any of
the sign-irons, his cane gave a different sound, and occasioned a
different kind of resistance to the hand, from what it did elsewhere;
and, attending more particularly to this circumstance, he found,
that every where, under the drip of those irons, the stones had ac-
quired a greater degree of solidity, and a wonderful hardness, so as
to resist any ordinary tool ; and gave, when struck upon, a metallic
sound : and this fact, by repeated observations, he was at length
most thoroughly convinced of. This observation of the Doctor's
was illustrated by some experiments, in which he ascertained, that,
by thus washing frequently pieces of Portland-stone with water im-
pregnated with rusty iron, they acquired a very sensible degree of
the hardness here described, and on being struck gave the metallic
sound. — Part of a horse-shoe was seen by the Doctor, on the sea-
coast, near Scarborough, incrusted with sea-sand ; and, although
the sand was but little tinctured with an ochry colour from the iron,
it had acquired the hardness of common grit-stone/'

Part of a ladder, with some of the steps, which Mr. Baillou, of
Florence, presented to the Emperor, and which was placed in the
Imperial Museum at Vienna, was most probably merely an incrus-
tation ; similar incrustations of ladders, &c. frequently occurring
at the incrustating springs in this kingdom : and Italy, from whence
it appears this cabinet specimen was sent, as we have already seen,
abounds with waters possessing this quality. Several authors relate
that formerly the handles of hatches, &c. were found in a petrified
state. But it should be considered, that formerly, also, the arrow-
heads and stone hatchets of the aborigines of some parts of Ger-
many, not very dissimilar from those we now receive from the South
Seas, were regarded as thunderbolts. Thus Lachmund says, the
names of CERAUNIA, Ceraunius Lapis, Donnerstein, and Donnerkeil,
were given to those stones which had fallen from the clouds at the
time of thunder, and which resemble hammers, hatchets, wedges, &c.

400

being perforated in the thicker part. He particularly mentions
one, which, he says, had been driven, by the force of the thunder,
twelve ells deep in the ground, in a wine-cellar ; another, which
had split a large oak, near lleburg ; and another, which had been
struck into a tree, by the power of the thunder, in a field near
Torga*. Thus also Wagner and Langj place the stony dice,
TESSERA LVSORIM FOSSILES LAPIDEM, among the petrified figured stones
assuming a regular form. These little white cubic, and exactly
marked stones, they describe as being found in the neighbourhood
of the city of Baden, being frequently turned up by the moles.
The considerable numbers which have been found encourage, they
think, the opinion of their having been the work of nature; but
finding it difficult to ascertain, whether they have really been pro-
duced by the labour of man, and strewed about this spot;. or whether
nature, eager to imitate the works of art, has formed them in her
sportive moments ; they satisfy themselves with exclaiming,

Natura certe

Multa tegit sacra involucra, nee ullis
Fas est scire quidem mortalibus omnia!

acknowledging that even the medicinal use of these fossil dice is
hitherto unknown ; but asserting that they were equally fit for play
with those which had been made by artj.

Yours, &c.

* Oryctographia Hildesheimensis, a D. Friderico Lachmund. 1659.

f Historia Natural. Helvet. fol. 329. Historia Lapidum Figuratorum Helvetia Ca-
roli Nicolai Langii, p. 68.

$ Tesserarum fossilium usus medicus hucusque incognitus est, praeterquam quod ad
Uisum non minims ac arte factae quadrant. — Hist. Lap. Fig. p. 69.

401

LETTER XLII.

VARIETIES OF PETRIFIED WOODS CONTINUED. ...THOSE PROCEED-
ING FROM THE OPERATIONS OF INSECTS. ...STARRY STONE OF
CHEMNITZ. ...TEREDO MARINA.

AMONG the numerous subjects of the mineral kingdom, which
manifest traces of having derived their original forms from the
energies of vegetable life, there are none whose ambiguous appear-
ances occasion more perplexity, than the substances to which the
present Letter is chiefly appropriated, the STARRY STONE (staaren-
stein) OF CHEMNITZ.

These stones, representations of which will be found in Plate
VIII. Fig. 1, 2, 3, &c. are chiefly found in the neighbourhood of
Chemnitz, and particularly near to Hillersdorf. Specimens of this
kind of stone have been said to have been also found near Belgrade :
and, in particular, one specimen has been mentioned, which was
reported to be one of the piles belonging to the bridge, which the
Romans had erected over the Danube. The general appearance of
most specimens of this stone convey the idea of its being fossil
wood; but those marks which dispose to this opinion, although most
evident in some, are, however, hardly, if at all, discoverable in
others. The hardness of these stones, in general, appears to be
nearly that of jasper, whilst in others it even seems to approach to
that of agate. The general colour of their ground is mostly of a
dark brown, sometimes inclining to a brick-dust red ; but, in dif-
ferent specimens, most of the common colours of fossil wood will
be found to form that of their several grounds. The circumstances,
however, which constitute the difference between these substances,

VOL. i. 3 F

402

and all the other different species of fossil wood, are the appearance
of oval or circular spots, from the size of a crow-quill to that of a
goose-quill, filled with a substance generally of a more crystalline
appearance, and of a different colour from the ground. The sub-
stances with which these spots are filled, are sometimes evidently
calcedonic ; sometimes they resemble cornelian ; and sometimes they
are complete onachyne agate. The margins of these spots are, com-
monly, well defined, by a circular or oval line ; in some instances
this line is hardly perceivable, but in others it is so thick, that be-
ing continued through the substance of the stone, it describes a per-
fect tubule. In the centre of these spots may be mostly discovered
starred bodies, differing in colour from the rest of the spot : the
stars varying in the number of their rays; some having only four,
whilst others have five, six, seven, and even eight rays. These stel-
lated bodies pass through the substance of the stone, so that the
Same star will be seen on the upper as on the under side. The
variegated surfaces of these stones give them a very curious ap-
pearance: the spots, which are of various colours, red, brown,
bluish white, &c. are generally quite distinguishable from the
ground ; whilst the central star is also, frequently, plainly distin-
guishable, from its differing again from the colour of the spot which
surrounds it. Thus a most pleasing mottled surface is formed,
such as cannot be described, and such as cannot well be copied
by art.

No inquiries which have been made, respecting these stellated
substances, have as yet terminated satisfactorily. Mr. Walch ob-
serves, that, in some of these stones, their ligneous origin is ren-
dered indubitable ; the fibres of the wood being discoverable in the
transverse, as well as in the longitudinal section of the fibres;
whilst in others, he allows it is by no means evident. But, as he
remarks the grand difficulty exists in determining the nature of
those substances which assume this stellated form, and which possess

403

colours so various, and so different from those of the other parts of
the stone. Some, with Mr. Schultz, have been decidedly of opi-
nion, that these stellated appearances proceeded from the filling up
of the natural pores of the wood, by the infiltration of a stony
matter ; the wood being of some exotic, and unknown kind of
tree, whose pores were of a stellated form. Some have attributed
the tubular part to the labour of some insect of the tubularia or
teredo kind ; and which they have imagined has been afterwards
selected, by some zoophyte, for its habitation ; whilst others have
conceived that the tube, as well as the star-like figure, were both
attributable to the same zoophyte. M. Genzmer was of opinion,
that these curiously formed bodies were originally a species of stel-
lated coral. Mr. Walch, finding a closer resemblance between these
bodies and the pentagonal stalks of the pentacrinus, concludes them
to have been a species of cartilaginous zoophytes. Mr. Scultz, by
rutting a stone containing these substances, in various directions,
ascertained that they are continued columnar bodies, some of which,
he says, are angular, others cylindrical, and some pyramidal. That
they have been a species of columnar asteriae, he thinks, is proved
by their longitudinal section displaying stria3 of two or three co-
lours ; the colour of the stone, for instance, appearing in a dark line,
with a red or whitish line on each side of it, formed by two pro-
jecting rays.

Anxious to form a correct judgment respecting these bodies, I
have eagerly furnished myself with every specimen of the kind
within my reach ; and imitating the labours of Mr. Schultz, have
obtained sections of these bodies in almost every direction ; but,
as you will perceive, without obtaining much positive information
respecting them. With respect to the first-mentioned opinion, that
of these stellated forms being derived from the natural pores of the
wood, I have to remark, that they are seen in three states, so widely
different as could not at all accord with this opinion. In the one,

404

the stars exist without any surrounding containing ring; in another,
as in Plate VIII. Fig. 1, they are surrounded by circular, or some-
what oval lines, which have the appearance of the section of the
longitudinal vessels of the plant, but uncommonly large; and in
another, they are surrounded by a ring, as at Fig. 3, which there
seems no difficulty in considering, as the tube formed by the teredo
navalis, or some such insect. This want of uniformity, takes away
much from the probability of their form depending on the natural
pores of a plant.

The opinion of their having been coralline bodies, is opposed by
the material difference observable in their internal structure. In
corals, indeed, there is somewhat of a stellated appearance, formed
by very fine lamellae passing from the centre to the circumference,
the intervening parts bearing rather the appearance of the petals of
a flower with the points towards the centre ; the reverse of which is
the appearance which is yielded by these stars, the rays or points
all tending outwards. Two very forcible objections exist against
their being, as some have supposed, the stalks of pentacrinites, or
the plumose encrinus ; in the first place, the stalks of the plumose
encrinus are so generally pentagonal, that, perhaps, not one devia-
tion will be found in ten thousand of their joints; whereas the rays
of these stellae are so inconstant in their number, that on one spe-
cimen of this fossil, of the size of the palm of the hand, may be
seen several of five, and of eight, and of every intermediate num-
ber of rays. In the second place, these stellated bodies are per-
fectly continuous in their length, whereas the stalk of the encrinus
is divided into joints, at less than each quarter of an inch. In op-
position to the opinion of the surrounding ring, as well as the star,
being the work of a zoophyte, must be placed the undoubted fact
of the stellated column, being sometimes found in a tube, evidently
the work of the teredo, or some similar insect.

405

From all these considerations, I am induced to conclude — that
these bodies do not assume their form from any natural pores of
the wood — that they are not coralline bodies— that they are not
stalks of pentacrinites — and that the surrounding ring has not, in
every case, been derived from the same origin as the contained
column. Thus much, I trust, may be asserted, with respect to what
these bodies are not ; but as to any opinions, as to what they really
may have been, these have been formed under such doubts, as to
require that I should offer them with hesitation. There appears
to be every reason to conclude, with Mr. Walch and others, that
this columnar body was originally a zoophyte, totally different
from any which are now known to exist ; and in very few respects,
indeed, analogous with any of those which we see in a fossil state.
It also appears, that one of the habitudes of this insect was that of
forming a tube, for its domicile, in any appropriate substance ; and
that decayed wood was most frequently, if not always, selected by
it for this purpose.

No section or specimen, which I have yet seen, allows us to deter-
mine whether the complete animal was in one continuous straight
columnar body, or whether it separated into ramifications: nor can
it be ascertained, by any specimens I have examined, what is the
natural termination of the ends of this substance ; no change of its
columnar form hav-ing been yet seen, which would authorize the
suspicion of its divaricating, and forming a head in the manner of
the encrinus.

Plate VII. Fig. 1. represents a specimen which gives a very fa-
vourable view of the general appearance which this stone yields :
it is not, however, so rich in colour, as some specimens are. On
the lower edge very plain traces of its ligneous origin may be per-
ceived, and towards the other edge may be seen several of the stel-
lated bodies in the tubules, to which some are attached at one side,
whilst others are exactly in the centre ; the other part of the tubule

406

being in some entirely empty, and in others either partly or com-
pletely filled by siliceous crystals.

Plate VII. Fig. 2. is a view of one of the sides of the above spe-
cimen, which possesses a striated and variegated appearance, from
its showing the perpendicular section of the tubuli, the contained
starred body, and the fossil wood which is interposed between the
tubuli. A careful examination shows that the stellated bodies them-
selves are in this direction striated. Fig. 3. represents a specimen
in which the marks of wood are very decided. The tubules in this
specimen have every appearance of having been formed by tere-
dines : possessing, in general, the same size and form with those
which are produced by this animal; being also lined with a similar
coating. The substance filling the tubules is constantly silicious ;
and sometimes, and particularly in this specimen, it is perfect agate,
in some parts of a reddish, and in others of a bluish white : the
stellated body being frequently to be seen, either in the centre, or
at the side of the agate. Fig. 5, 6, and 7> represent these stellated
bodies, with their surrounding tubules magnified to about five times
their natural size. When magnified to this degree, their substance
is discovered to be intersected by several curved lines, which doubt-
lessly formed the canals through which the fluid of the living animal
passed ; but the spaces of which being now filled with silicious
matter, an appearance is yielded very much resembling the plates
forming the exterior part of some echini and asteriae.

As the animal nature of these bodies can hardly be doubted, their
examination in this department of our inquiry seems to be hardly ad-
missible ; but as by far the greater number of the specimens in which
they are contained, are evidently of vegetable origin ; and as all the
specimens which I have seen may be considered as varieties of fossil
wood, differing from other fossil wood, only by the accident of the
introduction of this particular substance, these observations may be,
perhaps, introduced here, without any considerable impropriety.

407

Influenced by almost similar reasons, I shall here introduce some
remarks on that fossil wood, which is so frequently found on the
shore of Essex, as well as on the opposite shores, which, being hol-
lowed out into tubular cavities, apparently by the labours of the
teredo, has been distinguished by the name of Lapis Syringoides.

Representations of specimens of this stone are exhibited at
Plate VIII. Fig. 8, 9, 10, where the devastating labours of this
animal are sufficiently apparent.

It may not be amiss to remind you, that, from the time of Theo-
phrastus, the lignivorous powers of this creature have been known
and dreaded. Linnaeus describes it as a terebella, possessing two
calcareous hemispheres for cutting out, and two for piercing ; its
round bending shell piercing into the wood. Dr. Baster describes
its head as being of a most wonderful structure, being covered with
two hard shell-like hemicrania ; but of a substance, in reality, nei-
ther osseous nor testaceous. These hemicrania, which are whiter
than the rest of their bodies, he speaks of as exceeding in hardness
the testaceous tube they inhabit: their inner surface, he describes,
as being hollow and smooth ; and the outer, convex and rough,
having three ranges of fibres, passing in different directions. These
two hemicrania, which are connected by strong ligaments, and, as
it were, by a small hinge, by which they are able to dilate, without
separating, besides defending the soft head, are the instruments by
which the animal procures its food : since being placed in a manner
similar to a double bit of that kind of borer we call an augur,
whichever way the head is turned, the raised and rough fibres,
either of one direction, or of the other, rub off some of the parti-
cles of the wood*.

In the year 1?30, the persons appointed to take care of the dykes
on the coast of Holland and Zealand, observed that the piles made

* Philosophical Transactions, Vol. XLI. Part I. No. 455.

of even the hardest oak, and placed for the purpose of defending
the coast of the Netherlands against the sea, were eaten through,
in a few months ; and so weakened, as to be broken by the slightest
force. Surprised at this alarming phenomenon, they inquired into
its cause, and found that, by the astonishing increase in the number
of these animals, the inhabitants were threatened with the greatest
danger. To this alarm we owe the account given by Dr. Baster;
the inquiries of Dr. Massuet*; and the diffuse and elaborate, but
truly learned work of Sellius-f .

That the fossil remains of wood, here depicted, have derived
their present appearance from the devastation of these same crea-
tures, there is very little reason to doubt ; since we find in them
most of those characteristics of the testaceous habitation of the
teredo, which Sellius has so accurately described. We here see the
external small opening, dilating as it penetrates the substance of
the wood — the same testaceous tube, its external surface bearing
somewhat of an annular appearance ; whilst its internal part pre-
sents a finely polished surface, except where invested with lapideous
matter; and, in one specimen, an appearance resembling the hard
testaceous cutting hemispheres may be seen, left in the wood, which
they have been excavating, and petrified with it. In these speci-
mens we also discover the frequent close neighbourhood of the
different dwellings of these animals ; and remark, with admiration,
the care and wonderful contrivance by which they have guided
themselves, so that they should not render inconvenience to each
other ; reminding us, that

parcit

Cognatis maculis similis fera.

Thus we rarely see an instance of their at all invading each other's
premises, whilst pursuing their frequently tortuous passage ; but

* Recherches interessantes 1'Origine, &c. des diverses Especes de Vers, a Turgeau.
t Historia Naturalis Teredinis Marine.

409

each one pursues its allotted path and operations : and, like the
locusts, as mentioned by the prophet Joel (chap. ii. v. 7, 8.), so
aptly quoted by Sellius, " they march every one on his ways, and
they break not their ranks ; neither does one thrust another, they
walk every one in his path." This curious circumstance will appear
evidently on a view of Plate VIII. Fig. 9-

As in the ordinary fossil wood we have perceived that its lapi-
deous impregnation may be either effected by the introduction of
lime, silex, or alumine, so also, in this variety of fossil wood, simi-
lar impregnations are met with* In PI. VIII. Fig. 8. is represented
a most beautiful specimen of silicized bituminous wood, in which
the ravages of the teredo are very manifest. In this specimen, the
filtrated silicious matter, having acquired a strong brown or yel-
lowish tinge, perhaps from the admixture of fluid bitumen, fills up
one of the cavities, left by the worm, with a transparent topazine
calcedony, giving an appearance exactly resembling that of the
larva of some insect. Its other cavities are filled with a substance
so strictly agatine, as to possess not only the colours, but even the
lines, which characterize that species of agate called the fortification
agate. Fig. 10. of the same Plate represents a piece of silicized wood,
which has the appearance of having suffered but little change from
bitumini/ .tion ; having rather the appearance of a dry withered
wood. In this specimen the cavities formed by the teredo are uni-
fotinlv filled by a white pellucid calcedony, apparently free from
any for- ipi intermixture. Fig. 9. of the same Plate is from a spe-
ciincn "liich is impregnated with carbonate of lime, which, in a
spathose state, has filled several of the tubes formed by the teredo,
and invested the internal surtace of others. Frequently particles of
pyrites may be seen intermingled with the calcareous spar: and
nrntly also wili the wood be so permeated by clay, as to allow
it to he termed alununous wood ; employing the term in that loose

VOL. i. 3 G

410

sense, in which it has been already applied to fossil wood, into the
interstices of which clay has freely penetrated.

On putting a piece of this wood, impregnated with lime, into
diluted nitric acid, the same effects were produced as when other
calcareous fossil wood was subjected to the same experiment. The
carbonate of lime was decomposed, and, on the earth being re-
moved, the fibres of the wood were found in a loose and detached
state; of a dark brown colour, and burning with a white flame, and
a bituminous odour, on being applied to the flame of a candle.

I have, in a former Letter, remarked that the process of bitumi-
nization seems to be inimical to animal life ; and that, after any
vegetable substance has been exposed to its influence, it appears to
be no longer fitted to become the aliment of any animal. Nature
having now destined this matter to undergo a peculiar chemical
change, the first step is to prevent its being subject to any other
kind of alteration, which might interfere with this arrangement.
This is confirmed by the appearance of these specimens, in which
the wood has evidently been exposed to the process of bituminiza-
tion, since it had been subjected to the ravages of the teredines*,
These pieces of wood, I, therefore, conjecture to have lain in the
sea, subjected to the devastating labours of these animals, until,
by some of those changes, of which a former letter has aimed to
give, at least, some slight notion, they became overwhelmed with
earth ; and that, while thus buried, and secluded from the atmos-
phere, they passed into the bituminous fermentation ; and after-
wards, from the infiltration of certain lapidific juices, obtained their
present form of existence*.

* It seems to be deserving of trial, whether slightly bituminized wood might not be ad-
vantageously employed for ship's bottoms, and for other purposes, in which the ravages
of the ship-worm are particularly required to be guarded against. It even seems desirable
that it shoui i be ascertained, how far wood which has been involved in hay whilst forming
in the rick, would be protected against these animals.

411

M. Walch observes, that it is very rare to find shells, or the re-
mains of any marine animals, among mineralized wood. He knows,
he says, of very few instances indeed *. Scheuchzer describes a
specimen of fossil wood, to which is also affixed a fossil oyster -f-.
Davila also describes a piece of fossil wood to which an ammonite
adherered. I have in my possession a very beautiful specimen of
fossil wood, imbedded in a piece of the rock from Charmouth, in
which is also fixed a very perfect spathose ammonite, and other
specimens in which ostracitce are thus attached. But the fact ap-
pears to be really this, that this junction of animal, with vegetable
substances, in a fossil state, is only rare in those fossils which are
actually silicious.

Yours, &c.

LETTER XLIII.

SECONDARY VEGETABLE FOSSILS.. ..IN SCHISTI....IN SAND-STONA
....IN CALCAREOUS STRATA.. ..IN ARGILLACEOUS NODULES.

IT gives me much pleasure to learn, that you purpose to extend
your tour into Wales. The visiting of .Dorsetshire, Devonshire,
Somersetshire, and Gloucestershire, those vast mines of secondary
fossils, and the traversing of Wales, with that pleasing and instruc-
tive companion, Aikin's 'I our, in my hand, are among those wishes
which frequently arise, but which, hupe, reluctantly, refusing to
cherish, perish even, perhaps, the moment they are formed. liow
delighted should I be to view the wild Cambrian scenes, and to
trace the mountainous bottom of the antideluvian waters Nor
should 1 be less pleased at viewing the various specimens of

* Recueil des Monumens des Catastrophes, &c, torn. iii. p. 30.
t Oryctogr. Helvet. p. 240.

413

slates, impressed with vegetable forms, which you will there find
in great abundance. These you will frequently perceive to be so
perfect, that our sceptical friend Wilton will no longer be able to
hold out : he must, at last, give up the opinion, to which he has so
long, and so pertinaciously, adhered, that these are the productions
6f the wanton and fanciful sports of nature ; and must admit them
to have derived their forms from antediluvian vegetable remains.
With the hope of securing a convert, and of augmenting the plea-
sure which you must all experience, in the contemplation of these
wonders of nature, I shall, in this Letter, offer you a few observa-
tions on their origin and formation.

In most of the strata which are found immediately above coal,
decided marks and impressions of vegetables may be discovered :
but it seldom happens, that any traces appear on the strata, on
which the coal lays. A considerable difference also exists, between
the several kinds of strata which lay immediately above coal, as to
the quantity of vegetables they contain, and the state in which they
are found. The strata which, most commonly, form the matrices
of these vegetable remains, are of the schistose kind ; sometimes of
a bluish grey colour, nearly verging on black; sometimes of a dark
brown, but most frequently of a jet black. In these schisti, the
impressions are often disposed as smooth and flat, as if the plants
had been carefully placed between the leaves of an herbarium.
Where this is the case, and the vegetable remains thus form a sepa-
rating medium of considerable extent between the laminae of the
schist, the complete separation of these laminae is easily effected,
by a small well-directed force ; and the impressions of the vege-
tables are thereby clearly displayed.

The most beautiful specimens of this kind, are those, perhaps,
which are found in the coal-pits of Lancashire. Dr. Woodward
describes several fine specimens which he obtained from the Canel
coal-pits, near Haigh in Lancashire. The colliers there, he says, call
the substance on which they are formed black-baft : the colliers

415

about Newcastle and Durham call it plate. The stratum of this is
about a yard thick, lying 120 feet deep, and SO feet above the
Canel-coal. One specimen he describes as a black slaty coal,
marked in a quincunx manner, &c. much like what might have
proceeded from the bark of common fir. Another he describes
as having the appearance of long striated leaves, having the ap-
pearance of joints, &c. upon a dark grey slaty stone. The stra-
tum of this, he says, lay at the depth of 25 fathoms, in Bransty-
cliff, by the Duke of Somerset's salt-pans, near Whitehaven. The
stratum, he says, was about a foot and a half thick ; and upon the
breaking of the stone, leaves of plants appeared very thick in all parts
of it, where the grain of the stone was thus fine and dense. But
where it happened to be more gritty, coarse, and lax, there was not
one leaf to be met with*. Specimens of schisti thus bearing impres-
sions of vegetables are displayed Plate I. Fig. 6. and 7. ; Plate IV.
Fig. 6. and 7. ; and Plate V. Fig. 1, 2, 3, 6, 7, 8, 9.

The impressions of leaves are much more rarely discovered in the
sand-stone strata, and are traced with much more difficulty ; owing
in part to the uncertain direction, in which these stones often split ;
and, in part% to the leaves being twisted, and to their laying in a
confused and irregular direction : hence the leaf is generally divided
with the stone, and its edge, or section, only exposed. Sometimes,
however, a very fair impression of a leaf may be seen, on sand-
stone ; but it will be found, in general, to differ very much in some
respects from the impressions on the argillaceous schists. Plate V.
Fig. 4. and Plate III. Fig. 3, 4, and 5. represent the impression of
vegetables on different kinds of sand-stone.

The occurrence of vegetable remains in lime-stone strata is un-
doubtedly much more rare than in the argillaceous, or schisti.
Schultzen suspects some error in those accounts which state their

* Catalogue of English Fossils in the Collection of J. Woodward, M.D. Part II. p. 16.

414

having been observed ; and M. Walch, who entertains the same
suspicions with Schultzen, accounts for the rarity of their being
met with in iime-stone, or marble, to the calcareous mountains
having been formed at the bottom of the sea, where vegetable mat-
ter'would be least likely to accumulate; but that they do occur in
lime-stone strata is indubitable.

The remains and the impression of leaves of trees are frequently
found in the fissile calcareous stone of Oeningen, and in the calca-
reous stones of other parts ; some of these may, perhaps, with pro-
priety, be supposed to owe their present situation, to the changes of
very distant periods ; but others, especially those which are found in
stones, apparently of a tufaceous origin, have been thus entombed
in more modern times. Indeed it is rather to be expected, from
the frequent falling of leaves on the soft margaceous, or tufaceous
matter, on the borders of lakes and rivers, that instances of such
preservations of their remains, should be frequently met with ; which
is the case in many places in Germany and Italy, as well as in
several other parts of the world.

Rounded nodules of argillaceous iron frequently contain in their
centre the remains of plants, the forms of which are preserved in a
state of wonderful perfection. The most particular account of these
substances has been given by Dr. Woodward ; and, as it appears to
have been the result of his own observations, I have here transcribed
it. " These nodules, with leaves in them, are called Cat-heads, and
seem to consist of a sort of iron-stone, not unlike that which is
found very plentifully at Robinhood's-bay, in Yorkshire, and in the
rocks near Whitehaven, in Cumberland ; where they call them Cat-
scaups, and are frequently melted with the softer iron ores. These,
perhaps, differ not much from those described by Dr. Lister, de Font.
Med. by the name, as I remember, of Minerce FerriPilceformis, called
Ball-mine in Staffordshire. These cat-heads are found only at Ken-
ton, which is about two miles to the northward of Newcastle; and

415

Newbiggin, about a mile to the westward of Kenton. Those of
Kenton attend the stratum of coal ; but lie in a bed of blue chiver,
about a fathom thick, and have another stratum of black chiver of
the same thickness lying under them. They are generally about six
or seven fathom from the coal. Those of Newbiggin are but three
fathom above the coal. They have not always leaves in them ; in-
deed, not above one in five or six. When fresh taken forth, they
break difficultly and irregularly ; but when exposed awhile to the
air, they split easily, and part at the leaves. They are of several
sizes, from the bigness of a walnut to that of a man's fist. They
are found pretty plentifully ; and at about the depth of 40 fathom*."

The specimens depicted at Plate I. -Fig. 8., Plate III. Fig. 6.,
Plate IV. Fig. 1, 2, 3, 4, Plate V. Fig. 5, 6, 10, 11, are all of this
kind. These specimens are, however, not confined, as appears by
Dr. Woodward's account, to the neighbourhood of Newcastle ;
being also found in Derbyshire, and in Wales ; and, I conjecture, in
most places where masses of iron-stone accompany coal. Shrop-
shire abounds in these fossils. Since the former edition of this
volume, I have been favoured with a very interesting series of the
remains of plants in nodules, by Thomas Botfield, Esq. of Hopton
Court, Cleobury-Mortimer, Shropshire, in whose extensive works
they are very abundant.

The only specimens in which I have seen the impressions of leaves
insilicious stones are such pebbles as are figured at Plate III. Fig. 7.
which are, I believe, but rarely found. The pebble appears to have
been partly inveloped, whilst in a soft state, in a piece of a leaf, by
which it has acquired the marks which it bears on its surface.

Yours, &c.
* Catalogue of English Fossils, Part II. p. 14.

LETTER XLIV.

GREAT DIFFICULTY OF ASCERTAINING EVEN THE GENERA OF
THE PLANTS WHICH ARE THUS PRESERVED. ...DORSIFEROUS
PLANTS AND CACTI MOST COMMON.

AWARE of the difficulty of determining, from little more than the
outlines of a leaf, the species, or even genus, of the plant to which
it belonged ; and also well knowing that the greater part of the
remains of plants, thus preserved, have been acknowledged to have
belonged to plants not known to botanists ; I anxiously sought,
and was happy in obtaining, the aid of a gentleman* whose general
botanical knowledge has given him high rank among the disciples
of Linnaeus; and whose particular knowledge, respecting the dorsi-
ferous plants, would stamp considerable authority on any opinion
he should offer respecting this order, which comprehends by far the
greatest number of the objects of our present inquiry. But, though
possessing all the knowledge within the reach of an European
botanist, the close examination which he kindly made of the vege-
table remains depicted in Plate IV. and V. would only allow him to
give an opinion, on very few of them. These fossil remains of
vegetables are, he observes, a sort of botanical riddles ; and, with,
respect to those which appear to be ferns, the difficulty of deter-
mining to what species the several impressions may be referred,
is augmented by there being so many things which they may
be, and so many things which they nearly resemble, without
being the same. Of the figures represented in Plate IV. he was

* Dr. James Edward Smith, President of the Linnean Society, &c.

417

of opinion, that Fig. 1, 2. seemed to be a Pteris; Fig. 5. could not
be safely referred to any known species — but was most like a
Dicksonia. Of Fig 6. he observed, it might be an Osmunda ; but ac-
knowledgd that he knew nothing like it. Fig. 7- he observed, had
the habit of a Polypodium. Of the Figures in PL V. he was of opi-
nion, that Fig. 2. was probably an Adiantum ; and that Fig. 6. and
Fig. 9- were species of Polypodium. he also conjectured that they
were all foreign, and productions of a warm climate.

I cannot thus pass this kind communication, without more parti-
cularly pointing out to you, that the paucity of the information
thus gained results, not from want of kind exertions of those powers
of investigation, which this distinguished botanist possesses; but
from the absolute impossibility, at present, of further removing the
veil of mystery which time has placed over these substances. In
confirmation of this opinion it must be mentioned to you, that
Dr. Woodward joined to his own, the judgment of four gentlemen,
eminent for their knowledge in botany, Dr. Plukenet, Mr. Stone-
street, Mr. Buddie, and Mr. Doody, for the purpose of examining
that class of his specimens, which contained the leaves of plants.
The result of this examination appears to have been, that of 138
specimens they were only able td point out the eleven following
plants to which some of the specimens bore a decided resemblance.

1. Filix mas pinnulis angustis non dentatis.

2. Osmunda regalis.

3. Filix foem. vulg.

4. Filix mas vulg.

5. Filix minor palustris. Raii, p. 48, No. 6.

6. Adianthum alb. vulg. Taberm. S. Ruta Muraria, C. B. Raii

Synopsis, p. 48, No. 1.

7. Filix mas non ramosa pinnulis angustis raris profunde den-
tatis. Ger. Raii Synopsis, p. 48, No. 5.

VOL.I. 3 H

41

8. Filix minor non ramosa. J. B. vel Dryopteris. Ger. Raii

Synopsis, p. 48, No. 6.
9» Vafietas filicis maris vulg. Petiver. Raii Synopsis, p, 341.

1(X Typha palustris max. Parkinson. Raii Synopsis, p. 278.

11. Abies mas vulg. Raii, p. 287-

They found that 23 bore no resemblance to any plant known in
this country ; and the remaining 88 are such as appeared to be
like — were not unlike — or were very little different from certain known
plants. The doubtful manner in which these are spoken of, and
the little agreement which it is now known exists between these
impressions, and known recent plants, give us ground of supposi-
tion that these were the remains of plants which are unknown to
this country *.

The plant figured at PI. IV. Fig. 5. is evidently depicted also by
Scheuchzer in PI. I. Fig 7- p. 16. Herbarii Diluviani. He says,
" Est filicula, et quidem filicula fontana major, sive adianthum al-
bum filicis folio. C.B. Pin. 358. Adianthum album filicis folio.
J. B* III. 733," &c. The specimen agrees with that which is here
depicted, in other respects also. The stone, which came from Si-
lesia, is of a margaceous kind, and of an ash colour, tinged with
iron ; the plant itself being dark. The specimen of Scheuchzer
was also obtained from a coal-mine, at Altwasser, in Silesia.

The appearance of the specimen PI. III. Fig. 3. and which is
represented with the strictest fidelity, is exceedingly uncommon.
The matrix is a fine grained sand-stone ; and the vegetable form
which it bears is produced, merely, by a very superficial stain of
bitumen. Fig. 6. of the same Plate displays a fossil frequently
found in the iron-stone of Coalbrook-dale, of Derbyshire, &c. In
the centre may be discerned a stalk, with a reticulated, or rather

* A Catalogue of the English Fossils, &c. Part II. p. 9.

419

imbricated, surface, from which seem to proceed a considerable
number of thin, narrow leaves, by which it has been surrounded.
Its resemblance to any known plant is not sufficient to have allowed
any one to point out, with any confidence, the plant of which it
may have been a part. Scheuchzer thought it most resembled
" Equisetum, adhuc tenellum, in densam foliorum spicam, con-*
gestum; vel spica plantae alicujus hactenus ignota." Walch ima-
gined it to bear some analogy with the Myriophyllon, Lin mo i. Per-
haps, he says, it may be Millefolium aquaticum, flosculis ad folio-
rum nodos. The stalk, however, which, if not imbricated, has a
regular reticulated surface, proves it not to belong to either genus.
The ingenious Mr. Martin, in his descriptions of the petrifactions
of Derbyshire, considers this fossil as the stalk or stem of some lost,
or, at least, unknown vegetable, somewhat resembling a cone of the
fir-tree.

The fragments contained in the nodule Fig. 3, and 4, are not suf-
ficiently perfect to lead to any conjecture, as to the plant to which
they belong. They, however, serve, with Fig. 1, and 2, already de-
scribed, to illustrate the circumstance of the two surfaces of the
divided nodule representing the same side of the leaf as will be
attempted to be explained in our next Letter.

A similar specimen with that represented Plate V. Fig. 3. has also
been depictured by Volkman, from a schist from Silesia, whence this
specimen was also said to have been obtained. He describes it as
Rubia sylvestris, or molluga montana ; Gallium album latiiblium,
Gasp. Bauhin ; Gallium album, Tournefortii. M. Walch states it
to have been the opinion of M. Gunther, that it is the Rubia parva,
flore caeruleo, cauliculos per terram spargens, Joh. Bauhini. Lhwydd
has also figured it, Tab. V. Fig. 202. and describes it as Rubeola
mineralis, a fodinis Actonensibus, p. 12. Fig. 7- of the same Plate
seems to represent a part of the same plant, in an erect position,
manifesting it to be one of the verticillatce ; and, perhaps, also show-

420

ing, that the verticilli are nearer to each other, than in the plants
with which it has been compared. This specimen is an iron-stone,
the fractured surface being of a rusty colour. Fig. 4, of the same
Plate is a micaceous sand-stone, bearing a delicate, but very per-
fect and beautiful impression of a leaf, which, bearing no peculiar
characteristic marks, cannot be referred to any particular plant.
Fig. 5, of the same Plate represents the leaf of some plant, entirely
unknown, in an iron-stone nodule. The kind represented Fig. 9, of
the same Plate, on a coal schist from Wales, very much resembles
the specimen figured Tab. III. Fig. 7> of Scheuchzer's Diluvian
Herbarium, p. 19 ; of which he says, " haud abludit Filix non ra-
mosa major, pinnulis longis angustis, profunde dentatis, suprema
pinna longius mucronata." Pluk. Amalth. Botan. p. 93. tab. 403.
Fig. 10, is the remains, little more than the stalk appearing, of, per-
haps, an Equisetum, in an iron-stone, of a red colour, from Coal-
brook-dale, in Shropshire. Fig. 11. is also from Coalbrook-dale, and
is in an iron-stone of the same colour with the former. It contains
a plant probably of the same genus also : the fossil described by
Lhwydd, at No. 202, approaches near to it. This he describes as
Aparinae densius foliatae aemulum Lithophyton radiosum. E fodinis
Glamorgensis. The plants in both these specimens appear to be
unnaturally contracted or shrunk. Whether this appearance pro-
ceeds from the direction in which the leaves are placed, presenting
little more than their edges, I cannot determine : both specimens,
however, may owe their colour to the action of fire, to which they
may have been exposed. Fig. 8. of the same Plate represents one
of these impressions of schisti, already mentioned, as described by
Dr. Woodward, from the coal mines of Haigh, in Lancashire.

Mr. Da Costa, in a paper on the impressions of plants, on the
slates of coals (schistus terrestris niger carbonarius), found immedi-
ately on the coal stratum, not only of this kingdom, but in France,
Saxony, Bohemia, Silesia, &c. conjectures that they are impressions,

421

and parts of different species of pines, of tithymals, cereuses,
of large reeds, and of some arborescent plants. His account is
accompanied by engravings, the descriptions of which are neces-
sarily very short. His first figure is of an impression of a plant
with rhomboidal work on it, with which three long narrow leaves
were found, which appeared to belong to it. This specimen was
from Oswestry, in Shropshire ; a similar figure is given by Volck-
man, in his Silesia Subterranea, Tab. XXII. Fig. 2. ; and it seems
to resemble that described in Dr. Woodward's Catalogue, B. 107,
q. 22. q. 32. p. 106. The second and fourth seem to be of the reed
kind, having knobs placed in rows on their surface, like the vesicles
of some species of the rushes. This specimen seems to have been
similar to one described by Dr. Woodward, B. a. 1. p. 9- The third
impression he supposes to have derived its figure from some plant
of the fir kind. The fifth specimen is from Mostyn colliery, Flint-
shire : its surface, when attentively viewed, exhibits a reticular im-
pression of mesh-work, or rhomboidal hollows; the sides of the
rhombs, or the net-work, being raised in relief. In Plate I. Fig. 6.
you will find the representation of a similar specimen from France ;
and serves as an instance of the peculiarity of surface these im-
pressions frequently possess. The appearance here so varying, with
the change of light, as hardly to admit a fair representation of the
proteal surface ; the artist, with every exertion, was not able to
succeed to his wish in this respect ; since although in some points
of view the rhomboidal form would appear, in most others the
transition into somewhat of an oval appearance would be dis-
coverable. In the centre of these projecting bodies, small holes are
observable, being such as might be expected for the insertion of
seta3, or of setaceous leaves. In the sixth of Mr. Da Costa's spe-
cimens, studs, apparently also for the insertion of setae, are regu-

* Philosophical Transactions, Vol. L. Parti, p. 228.

422

larly disposed in the wider and almost oval interstices, between the
nearly semicircular receding waves of undulating lines. This form,
so difficult to describe correctly, is well represented in the third
number of Mr. Martin's Derbyshire Petrifactions. It is also to be
seen in Volckman's Silesia Subterranea.

Plate III. Tab. IV. Fig. 9. Mr. Da Costa's sixth figure, you will
find is very successfully represented in PI. V. No. 8. A careful exa-
mination of the specimen from which this figure was drawn, furnishes
some information respecting the nature and the formation of these
fossils. This specimen, evidently a piece of shale not quite half an
inch in thickness, bears a similar impression on each side ; and having
been purposely placed in water, and allowed to remain there about
two hours, became very soft and friable : the internal part becoming
resolved into a pulpy mass, which had evidently been formed of a
confused heap of grass, and other vegetable matters, intermixed
with dark argillaceous earth. The external part appeared to have
been the epidermis of some species of cactus : the internal suc-
culent part having been washed away, and its place supplied by
these foreign matters, which have become enclosed in it, and have
prevented its sides from having quite collapsed together. Thus
may we account for the different degrees of thickness which these
fossils possess ; this depending partly on their original form, and
partly at the distance at which the outer coat has been kept during
the resolution of their internal substance. The form of these fossils
may depend also on another circumstance. The plant being buried
in a soft margaceous mass, its external coat may remain attached
to the inside of the mould, which it had formed, whilst the cavity,
left by the resolution of its internal succulent part, would gradually
be filled up by the introduction of earthy matter. The cortical
part, thus enclosed in earthy matter, would undergo the bituminous
change; and the bitumen, thus filling up the impressions in the
mould, which the external surface had formed, would present the

423

s ,

exact figure of the original surface. That such a change has been
produced, and that the cortical part of these plants was much
thicker than any of the succulent plants now known, is evinced in
numerous specimens. So different, indeed, do these plants appear
to have been from any vegetable now known, as to give full reason
for supposing them to have belonged to a tribe entirely lost.

Every oryctologist is aware of the difficulty of giving names to
fossil plants, each schistous stratum being an immense herbarium,
of which every separated schist is a folio, on which are depicted
the figures of plants of the old world : most of which it is proba-
ble no longer exist. Not only is it difficult, with many fossil
plants, to determine the species and genera in which they should
be placed ; but frequently it happens, that their appearances differ
so much from those plants with which we are acquainted, that it is
not possible even to determine their proper station in the natural
orders of plants. Among the remains of plants of this latter de-
scription may be mentioned those of which we have been just
speaking, the appearances of which seem to be such as to defy
description. You have already observed the avowed inability of
Dr. Woodward and Mr. Da Costa to form a judgment of their na-
ture, or give a satisfactory account of the appearances which they
present: a later writer, M. Walch, appears to have experienced no
less difficulty. In one specimen of this kind, he remarks, the ap-
pearances are such, as would have been produced by the feet of a
kid, and even suggests that the impressions on its surface might
have been the track of some such animal.

To particularize all the different known plants which have been
supposed, by different authors, to have been seen in a fossil state,
would employ much more room than can be allotted here for that
purpose, especially when we are, at the same time, taught how little
reliance can be placed on the opinions thus given. It is, perhaps,
sufficient to say, that the fossil plants of Germany, have been de-

424

scribed by Leibnitz ; those of Saxony, by Mihlius ; those of France,
and particularly those of Saint Chaumont, in the Lionnois, by Jus-
sieu ; and those of England, by Dr. AVoodward, Mr. Lhwydd, and
Dr. Dickinson. Even the Antediluvian Herbarium of the learned
and indefatigable Scheuchzer cannot be relied on : but, on the
contrary, by far the greater part of the specimens, mentioned by
him, appear to have very doubtful claims to the names which they
have obtained. Nor is this to be wondered at, when it is consi-
dered, that these were collected from the writings of men, who,
although of acknowledged learning, had written when this science
was still in a considerable degree of obscurity.

Yours, &c.

LETTER XLV.

FOSSIL STEMS OF PLANTS. ...OF THE REED, &C FOSSILIUM

INCOGNITUM.

THE fossil stems of plants (Phytolithi Caulis, Wallerii et Linnaei,
Lithocalami, nonnul.) occur very frequently. They most commonly
belong to the family of grasses ; and have been sometimes supposed
to be analogous with some of the known species of the reed kind.
Thus Scheuchzer figures Arundo Sativa, Gasp. Bauhin, in a schist
from the coal mines of England*. Volckman also figures the Arundo
Saccharma-^. The Acorus has also been said, by Scheuchzer, to be
found in a petrified state ; and common Bamboo is mentioned, by
Walch, as having also undergone this change. But a review of

* Herb. Diluv, Tab. IV. Fig. i. f Siles. Subterr. Tab. XIIL Fig. 7.

425

the fossils of this kind njentioned by Dr. Woodward, and others,
will show that very few indeed of this numerous species can now
obtain any other denomination than that of fossilia incognita; bo-
tanists not having yet been able to discover any existing analogous
plants. Plate III. Fig. 3, represents a fossil of this description from
Chepstow, in Monmouthshire. This, as well as most others of this
kind, is little more than an impression, covered with a bituminous film,
of a very inconsiderable thickness, its internal part being entirely
sand-stone. The explanation of this circumstance does not, how-
ever, appear very difficult. The plant, having been surrounded by
the soft, or fluid, materials, of which the sand-stone has been since
formed, its internal succulent part would soon waste away, and its
place be filled with the soft magma; whilst the more solid and lig-
neous epidermis would remain, and, after a time, would give its
correct impression to the surrounding lapidifying matter. Then
passing through the bituminous change, it would fill its own mould
with its own altered substance, forming such a surface, as the sur-
rounding stony matter would adhere to but slightly ; and would
therefore dispose to that separation, by which its form is displayed.
This fossil is frequently found, where strata of sand-stone are
found nigh to the strata of coal, in various parts of England and
of Wales. Mr. Martin says he has seen single joints of this fossil
in iron-stone; and one in particular, of a large size, measuring
about twelve inches in circumference. Mr. Da Costa relates, that
in the collieries at Swanwich, in Derbyshire, in 1752, a plant of the
cane kind was found, fourteen feet long : it ended in a point at one
end, and at the root in a large knot ; and in the middle measured
nine inches about*. He also mentions, that Dr. Woodward describes
two specimens of this kind ; one a yard long, and the other six feet
and a half in length. Reference to Dr. Woodward's Catalogue

* Philosophical Transactions, Vol. L. Part I. p. 2S1.
VOL.. I. 3 I

426

shows that Mr. Da Costa was mistaken ; the specimens, of which
he speaks, had, instead of tiie smooth, or the striated surface of
gramma, studs, or tuhercules, over the greatest part of its surface*.
But Dr. Woodward mentions another specimen, apparently of the
reed tribe, which was originally two feet long.

The same circuit stance is observable in these fossils, as has been
mentioned when speaking of the vegetable remains in the iron
nodules. Very frequently, indeed, will the bituminizating process
have proceeded to the formation of the black bitumen, or jet, and
canel-coal ; such 1ms been the case in the specimen already referred
to, Plate III. Fig. 3, sevqral particles of black bituminous matter
being yet adherent, at the transverse sulcm or joint.

The specimens of Dr. Woodward, referred by Mr. Da Costa to
the reed tribe, are undoubtedly similar fossils to that described
Plate III. Fig. 1, and which is indeed, in many respects, a most
surprising and interesting fossil, These fossils diifer much in their
length from the size of that which is here depicted, to those men-
tioned by Dr. Woodward : one of which was five feet, and the other
six feet and a half long-j~. They also differ very much in their thick-
ness, the most common size being less than that of a man's arm ;
but Mr. Martin observes, that they are sometimes met with of four
or five times that size. The substance of these fossils is either a
fine grit-stone, with small micaceous particles, or a stone in which
no grit appears ; but such a mixture of argillaceous and silicious
earth as approaches to a jasper -, the colour of both these kinds of
stones varying, with different shades, from the lightest, to almost the
darkest brown. The general figure of this fossil is that of a long,
irregular, and compressed cylinder; the surface of which is pretty
thickly beset, in quincunx order, with holes, from the bottom of

* Catalogue of English Fossils, Part II. p. 104. q. 1.
t Ibid. Part I. p. 104. q. 1. and Part II. p. 59. h. 34.

which rsie small papillce, like tubercules ; but which, being sunk in
the hollows, hardly ever rise above the general surface. A sub-
stance with a rough imbricated surface, and about one sixteenth of
the thickness of the whole fossil, is frequently found passing
through the centre of the cylinder, but more to the compressed
side ; and frequently a sulcus, one edge of which rises into a sharp-
ish ridge, may be observed to run in a line parallel with it.

No conjecture, on which we can venture to rely, has yet been
offered with respect to this fossil. The Arbor Lavendulce Foliis,
Dr. Woodward says, hath studs, like these, and set in the same
quincunx order. Mr. Whitehurst thinks it most resembles the re-
mains of an Euphorbia, of the East Indies*. Indeed, there would
be little difficulty in referring it, either to the genus Euphorbia, or to
Cactus, were it not for the difficulty of explaining the nature of the
internal substance. The surfaces, both internal and external, are
frequently covered with a bituminous matter; the interstice being
closely filled with stony matter, which would dispose to the sus-
picion of their having been distinct vegetable bodies, which acci-
dent has thus united ; but, on the other hand, the frequency with
which they are found connected, and the similarity of the mode
in which they always appear to have been united, seem ta point
out that union to be natural, and hot accidental. Dr. Woodward
described this internal body, in his earlier specimens, as a medulla
or pith; but afterwards, a more careful view of this body, he
says, brought him to think it rather a commencement or beginning
of a branch, arising out of the main trunk -f. The data which
we possess would almost lead to the supposition, that the plant, to
which this fossil owes its origin, was of the succulent kind, which
contained a more solid part in. its succulent substance — but con-

* Inquiry into the Original State and Formation of the Earth, p. 203,
f. Catalogue of English Fossils, Part JL, p. 60.

428

jecture seems to be useless ; since the plant appears to have dif-
fered so much from any thing which we now know, as to leave
us without the opportunity of deriving any aid from analogy, and
but little from comparison. The variety in the shape, size, and
disposal of the tubercles on the surface of this fossil, appears to
be sufficient, to warrant the supposition that the genera and species
of this unknown family must have been very numerous. Unable
to find sufficient points of correspondence between it, and any plant
which is now known to exist, we must be satisfied, with Dr. Wood-
ward, whose opportunities for judgment, from the multitude of
his specimens, perhaps exceeded those of any one else, to submit
to leave it among the fossilia incognita.

The specimen figured at Plate IX. Fig. 1, and which was obtained
since the foregoing observations were committed to writing, seems
to furnish, at least, another conjecture, respecting this extraordinary
fossil. In this specimen, of itself highly interesting, is an oblong
cylindrical body, which is curiously imbricated on its surface, evi-
dently by the particular arrangement of squama? ; from which mem-
branous productions, exceedingly thin, forming tubuli, pass directly
inwards, in a perpendicular direction, \o another body placed in
the centre of the former. The external surface of this body is also
imbricated in a somewhat similar manner, obviously from the regu-
lar insertions of the terminations of the membranous productions,
proceeding from the external squamce. A reference to the figure
will show the external and internal imbricated surface, as well as
the membranous productions, forming tubuli, by which both are
connected ; manifesting this fossil to have been a Strobilus, analo-
gous in its organization, though different in its form, from any at
present known.

From the perfect state of seclusion in which this body has been
kept, by the close texture of the surrounding argillaceous iron-stone,
its bituminization has been complete, so that all its parts have been

429

•preserved and are now to be seen in their natural situation. But
if, instead of having been thus closely enveloped by argillaceous
matter, it had been surrounded by a loose arenaceous mass, and
under circumstances less favourable to bituminization, the harder
part only of the squamae, and the central receptaculurn, would have
obtained a prolonged duration of their original form ; whilst the
connecting membranous substances would have wasted away, and,
as they disappeared, the space they possessed would have become
filled up by earthy particles. Thus at a future distant period
there would be produced a stony substance with an imbricated sur-
face, containing within it another substance with a surface imbri-
cated in almost a similar manner. In- a word, a fossil would be
formed, which, in its general characters, would resemble the fossil
which has so particularly engaged our attention. It must, indeed,
be admitted, that the fossil vegetable figured at PI. IX. Fig. 1, the
extended outline to which marks the shape of the complete Strobilus,
as shown by the aid of another specimen, does not accord, in its
size, with the fossil with which it has been attempted to demonstrate
that it bears some analogy. The difference in size, however, affords
no material difficulty ; and the difference in the markings on the
surface, points out only perhaps a specific difference between these
supposed strobuli ; but two other circumstances demand still
further examination. One of these is, that the markings, as is fre-
quently the case, and as is the case with the fossil at PI. III. Fig 1,
is formed of detached spots or impressions, without any line pointing
out the figures of the squama ; but this appears to depend on cir-
cumstances being favourable, or otherwise, to the forming of the
impression ; since, in a fossil of this kind, nearly half a yard in
length, and about two inches and a half in its largest diameter, the
lines formed by the edges of the squama3 are distinctly observable;
so that nothing remains to contradict its origin having been that
which is here supposed, except its extraordinary length and

430

narrowness, when compared with the cones of the genus Pinus.
This is the other circumstance to which I alluded ; but this form, it
is to be remarked, is in perfect agreement with the proportions of
the supposed fossil strobilus at PL IX. Fig. 1, and is to be con-
sidered as strengthening the opinion, that many genera, as well as
species, of vegetables, have existed, and been destroyed ; and of
which we have no other traces than their remains in a fossil state.
For some very excellent observations on this curious fossil, I must
refer you to that elegant work, Petrificata Derbiensia.

The fossil at PI. X. Fig. 1, also serves, in my opinion, to explain
the nature of the fossil depicted at PL III. Fig. 6, and already
spoken of in a former Letter ; since, if the conjectures just offered
be right, this fossil, which has so much puzzled oryctologists, may
with the greatest reason be supposed to be the Amentum, or Catkin,
from which that kind of strobilus, the existence of which has been
just inferred, has been formed. The specimen depicted at PL IX.
Fig. 10, serves also to render more probable, that the flattened
specimens already described, and figured at PL I. Fig. 6 and .7?
and PL V. Fig. 8, are the remains of plants of the succulent tribe.
Every appearance which this specimen presents, serves to show that
it very nearly resembles the Cactus Cochenilifer, one of those plants
generally known by the name of Indian figs; and on which that

curious insect, the Cochineal (Coccus Cacti) feeds and inhabits.

\
\

Yours, &c.

LETTER XLVL

REMARKS ON LEAVES CONTAINED IN NODULES. ...IMPRESSIONS
X)F THE SAME SIDE OF THE LEAF ON EACH NODULE.... AC-
COUNTED FOR BY JUSSIEU, SCHULTZ, &C.... EXPLANATION PRO-
POSED.

I AM thoroughly aware of the circumstance to which our friend
Winton alludes. He desires you to inform me, that he will never
believe the impressions on the two halves, of the nodule he has sent
me, are the impressions of a real leaf, until I can inform him if, by
involving a guinea in plaster of Paris, I could obtain two impres->
sions of the king's head, without any impression of the reverse.
The circumstance to which he refers has puzzled some of our most
eminent lithologists.

An instance of the erroneous opinions which have prevailed re-
specting these subjects will be found in the remarks of our coun-
tryman, Dr. Leigh*. " In the rocks in these parts are only found
Polypody, Wall Rue, Scolopendrium, or leaves of thorns; doubt-
less other leaves, as well as these, would have occurred to our ob-
servation, had these been deposited here by Noah's deluge. — My
sentiment of the whole is this, that as it is observable in chymistry
that the salts of some plants will divaricate themselves into the
figures of the plants, that these representations of plants in rocks
are nothing but different concretions of saline, bituminous, and
terrene particles."

* The Natural History of Lancashire, Cheshire, &c. by Charles Leigh, M.D. 1700, p.99.

432

Various conjectures have been formed, but none have proved
successful, in satisfactorily explaining, why the impressions, on
both halves of the nodule, should represent the same side of
the leaf. The leaf itself, which formed the impression, being no
longer to be found, it was expected that it would uniformly
have left on the mass, in which it was enveloped, the impression
of its upper, and of its under surface ; but, in by far the greater
number of instances, this is not the case ; but, on the contrary,
the one half of one of these split nodules will be found to bear
the impression of, for instance, the under side of the leaf in basso
relievo ; the projecting parts of the leaf having produced in its
impression corresponding depressions; and on the counterpart of
the nodule will be found the impression of the same side of the
leaf in alto relievo ; in the same manner as if the leaf itself, which
had given the impression, had remained there. M. Jussieu endea-
voured to explain this curious phenomenon, by supposing that the
plants or leaves must have floated on water containing muddy
bituminous particles, which would by degrees deposit on the leaves
the particles with which it was loaded. By the continued applica-
tion of these particles, crusts, he supposed, would be formed on the
leaves, which would bear the figures and impressions of the leaves
exactly. On the leaves perishing, the crust, thus formed on the
surface of the leaf, would sink, and, settling on the soft mud, would
give a copy of the impression which the leaf had formed; which
would have the exact similar surface, with that which the leaf
itself would have presented : the bituminous matter with which
the leaf had been charged, from the water in which it had swam,
having given to the mould such a surface as would prevent the
cast from adhering to it. M. Schultz endeavoured to account for
this circumstance in another way. He supposed that the leaf
had become involved in a soft earthy matter; and that, as this
dried, the leaf perished, and left its mould, bearing the impressioa

435

of both its upper and under side. At some distant period, he
poses, that some bituminous matter insinuated itself, and filled the
cavity which the leaf had left; and that, on dividing the nodule^
the bitumen remains adherent to one side; and being separated
from the other, it exhibits the form which it has derived from the
mould on that side, whilst the mould itself is displayed on the
counterpart of the nodule.

You will, doubtless, agree, if the theory proposed respecting the
bituminization of vegetable matter accord with the phenomena
which are yielded by the vegetable remains thus incarcerated in
nodules, that considerable additional confirmation of that theory
will be thereby produced ; especially if it serves to explain satis-
factorily those circumstances which otherwise appear so inexpli-
cable.

The polished surface^ and sharpness .of impression, observable in
schisti bearing the characteristic traces of vegetables, manifest that
the substance thus impressed must have been in a very soft or fluid
state, when the impressing vegetable substance was applied to it.
The disappearance of the impressing vegetable substance implies,
that its resolution must have taken place, whilst excluded from the
air by the surrounding mass ; whilst every appearance seems to point
out, that the change, which it has undergone, has been similar to that
by which jet .and the bitumens, in general, have been formed.

The nature of the change which the leaf, or other vegetable mat-
ter undergoes, whilst in this secluded state, is demonstrated still
more plainly, on an examination of the impressions of plants on
sand-stone ; since here the colour of the stone> which is generally
of a light yellow or brown, allows the colour which the changed
vegetable matter assumes to be distinctly seen. This is the case in
PL III. Fig. 3, 4> and 5 ; and PI. V. Fig. 4 ; in which it may be
plainly seen, that the marks proceed not from impression merely,
not in fact from vegetable matter, but from bitumen in a soft state.

VOL. i. 3 K

434

This is particularly obvious in the specimen represented at PL III.
Fig. 5; in which, on examining it by aid of a magnifying glass,
the projecting particles of the sand-stone will be seen tinged, as if
they had been slightly touched with a brush dipped in light brown
bitumen. In the other specimens, just mentioned, the appearances
are similar, except as to the difference of colour, which is some-
times so dark as nearly to approach, as in Fig. 3, to black. In the
specimen No. 4, the sand-stone is coloured brown beneath the
surface, as if by the penetration of the fluid bitumen, which the
loose gritty texture of the stone would doubtlessly have readily
admitted.

The iron-stone nodule, on being split, affords the most satisfac-
tory evidence as to the nature of the change which the vegetable
matter undergoes in these cases, since here, bitumen will uniformly
be found to have taken the place, which vegetable matter had ori-
ginally possessed. Reverting, therefore, only to the position, that
vegetable matter, secluded from the air, in a moist situation, will
pass through a certain fermentative process, by which it will be
^converted to bitumen ; the key to this enigmatic phenomenon is at
once found. The leaf, involved in the tenacious argillaceous mat-
ter, necessarily forms a mould bearing its exact form ; and after a
certain period, during which the surrounding mass acquires a greater
degree of hardness, and a nodular form, the vegetable matter
changes into bitumen, which fills the mould, and assumes exactly
the same form which the leaf originally bore. If, therefore, the
nodule be now split, one of these two circumstances will occur*—
either the bitumen will, by the breaking of the nodule, be separated
and lost, leaving the impressions on both sides of the leaf perfect:
or, as is most commonly the case, it will separate from one side
only, and adhere to the other; when the side from which it has
separated will yield the impression of the leaf, and the bituminous
•matter itself, possessing the place of the leaf, will present a surface

similar to that of the leaf, from which the impression was origi*
nally derived. The separated flake of bitumen, mentioned in the
first case, has in some instances been preserved ; the description
which has been given of it, it being said to resemble a piece of
leather or parchment, agreeing much better with its possessing a
bituminous nature, than its being a mere dried leaf.

In objection to the proposed explanation of the change, which,
the vegetable matter undergoes in these nodules, it will occur to
many, that the bituminization being performed, under circumstances >
so favourable to it, there is reason to expect, that the process would
pass on to its completion, and that sometimes jet, and the darker
bitumens, might be thus formed. It is therefore necessary to state,,
that this does sometimes happen. Fig. 8,. in .Plate -I. furnishes an
instance of this circumstance. It appears to be the remains of a
tuberculated branch of some tree of the pine kind, which has been
involved in a nodule of iron-stone, the projecting parts of which
are covered with a jet-like bitumen.

The fossil leaf has been said, in many instances, to have been
detached from the surface to which it adheres. This is said to have
been done by Lhwydd, Buttner, Henkel, Jussieu, and others; but
that it was a bituminous, and not a vegetable substance, which was
thus found, is evident from their relations. Volckman, who also
thus detached them, states, that he found that the earthy particles
of the leaves had been deprived of their aqueous and volatile parts ;
and that, in the place of these, a bituminous matter had insinuated
itself*. Walch also remarks, that these leaves should rather be said
to be mineralized, than petrified ; since the deficiency arising from
the escape of the aqueous and volatile parts is, in his opinion, sup-
plied by the addition of bitumen, which he considers as a subject
of the mineral kingdom.

* Silesia Subterranea, p. 105.

436

In the specimen depicted Plate IV. Fig. 5, a circumstance is ob-
servable, which is, in this place, highly deserving of observation.
Lhwydd and others remark, that sometimes, though rarely, the leaf
will be found so well preserved, that even the colour may be dis-
cerned : and in this specimen the marks of the leaves are evidently
of a very dark olive green. But an accurate inspection with a lens
demonstrates that the same circumstance has occurred here, which
is frequently met with in the bituminization of wood — the bitumi-
nous matter retains the colour of the vegetable substance from
which it derived its origin — that which appears to be the leaf being
evidently a thin shining bituminous film.

Yours, &c.

LETTER XLVII.

tFOSSTL FLOWERS.. ..THEIR EXISTENCE DOUBTFUL... .FOSSIL SEEDS
AND SEED VESSELS. ...FOSSIL FRUITS.

W HEN the extreme delicacy of structure is considered, which
belongs to the flowers of plants, little expectation can be enter-
tained of often finding these in a petrified state. The tender and
almost succulent substance of the petals, stamina, and pistilla,
will furnish very little reason for supposing, that they should resist
a destructive resolution, sufficiently long to allow them to pass
through those chemical changes, by which such duration would
be given to their original forms, as would secure their passing
unchanged, in their figure, from the vegetable to the mineral
-kingdom.

437

This consideration necessarily leads us to doubt, if any reliance
can be placed on the accounts which have been given, by different
authors, respecting the existence of fossil flowers. Indeed, the ear-
lier writers on this science too frequently admitted resemblances,
when the connection between the supposed model and archetype
were too equivocal to authorize them. Thus Mylius imagined that
he traced the flower of the mouse-ear on a flint, and the rose of
Jericho on a schist from Manebach ; both of which M. Walch be-
lieves were, in reality, merely impressions of trochites. Not having
myself seen any fossil which can with certainty be said to have had
such an origin ; nor having seen any representation, or description,
which would fully authorize the admission of their existence ; and
not conceiving that the supposed fossil flowers of plants, of the
verticillated order, would be capable of being distinguished in that
state, I have not ventured to introduce the delineation of a fossil
flower ( Antholithus ) ; nor does it seem necessary to dwell longer
on the consideration of substances, whose existence is merely con-
jectural.

Our inquwfcs respecting the remains of the seeds and seed-vessels
of different vegetables, Spermolithi, Linn, of former ages, may be
hoped to be rather more successful ; since these do sometimes pos-
sess such a degree of solidity, as when they are placed in situations
which prohibit their vegetation, will allow of their duration, until
their bituminous change is effected.

This necessary degree of hardness will chiefly be found in those
fruits or seeds, the external parts of which have a tough ligamentous
covering, like that of the chesnut ; a hard scaly covering as in the
cone of the pine-tree, where the pericarp,, formed from an amentum,
consists of hard scales laying over each other ; a tough farinaceous
substance which becomes dry and hard, as in the coffee-berry ; an
osseous or bony covering, as in the hazel-nut ; or a still harder in-
vestiture, as the stone of pulpy, or fleshy fruits (drupce).

438

Bajer describes several stones, bearing a near resemblance to
fruits ; such as olive, almond, plurn, and cherry-stones, apples,
pears*, &c. But that these are accidentally figured stones, not
deriving their forms from the fruits they resemble, is most probable,
from the manner in which they are spoken of, he considering them
himself rather as sports of nature. Among these, is one said to
appear like a pod of capsicum ; whilst another is said exactly to
resemble a musk-pear, a fragment of a shell completely sup-
plying the place of a stalk.

Scheuchzer describes a petrified nutmeg, as being a white flint
of a compressed cylindrical form, marked with striae passing from
one end to the other, and bearing a strong resemblance to the
nutmeg-)-. The figure, however, certainly more resembles that of a
coralloid than of a nutmeg. He also figures, in Fig. 89 of the
same work, a pyritous fossil fruit of a very curious structure, which
is sulcated from the apex to the base, and marked with small pro*
jecting points along its lower edge, so as to give it somewhat of the
appearance of a coronet.

Helwing mentions a petrified walnut, in such a manner, as to lead
to the supposition that its resemblance to the fruit itself must have
been very close. The petrifaction of an almond, mentioned by this
author, does not seem to have approached the fruit very nearly in
similitude. He also describes a black stone as being very like to a
small smooth bean J. But when it is considered, that at this period
the notions entertained respecting the petrifaction of vegetable sub-
stances were so incorrect, that the petrified spines of the echinus,
or sea-urchin, were referred to the vegetable kingdom ; and that
the accidental forms of pyrites, as well as of argillaceous, and sili-

* Oryctographia Norica, p. 45.

t Lithographia Helvetia, p. 42. Fig. 57.

t Lithographia Angerburgica, p. 37.

439

cious pebbles, must often approach to the globular, or oval form
of fruits, these accounts should be received with some degree of
hesitation. With a similar degree of scepticism should several of
the petrified fruits be regarded which have been described by
Mylius, Volckman, and others: the necessity o f which caution
must be evident, when it is considered, that Scheuchzer has col-
lected, in his Herbarium Diluvianum, and Appendix, many sup-
posed fossil fruits which certainly have no right to be so consi-
dered.

In the museum of the late John Hunter, Esq. now in the pos-
session of the Royal College of Surgeons, is a substance which has
been considered as a fossil walnut ; appearing to have been formed
from the internal part of the nut only : and in the British Museum
is the corresponding part. It bears an exact resemblance in form
and colour, to its supposed prototype, except being of a whiter
colour, than the inner part of a walnut would be after a few months
keeping. From this circumstance chiefly I am led to suspect this
rather to be a specimen of human ingenuity, than of a vegetable
substance, changed in its nature, by a natural process.

In the Philosophical Transactions* several of the fossil fruits are
figured and described, which have been discovered in the Isle of
Sheppey, and which were sent to James Parsons, M. D. by Mr. Jacob,
who published, at the end of his Planter Favershamensis, an account
of the fossils he had collected there in the course of thirty years.
Among these appear to have been a small plum-stone, a cherry-
stone, a berry of the Sapindus, or soap-tree of America ; the ex-
ternal husk of the fruit of the Sapindus ; a young sand-box, or
fruit of the Hura; coffee-berries; an acorn, without its cup: be-
sides these he describes others, of the original nature of which he
seems to be less confident ; among these are two species of beans ;
a compressed pod, resembling the Arachidna, or under-ground pea;

* Philosoph. Transactions, Vol. L. Parti, p. 39fi.

440

a seed resembling the seed of some large gourd ; some exotic fruit,
like a small melon ; a stone resembling that of an East-India mango ;
a fruit somewhat resembling that of the Euonymus latifolius of
Cluvius ; a small bean, resembling a horse-bean ; a species of ches-
nut, like the horse chesnut of America ; a fruit resembling a small
Palma Cocoa ; another, seeming to be a species of foreign walnut;
and others, which seemed to resemble Myrobolans and Phaseoli.

From the state in which these were found, and from want of
their accordance, in many respects, with the seeds or fruits which
they are said to resemble, Dr. Parsons, very properly, does not too
strenuously insist on their having been those identical seeds, or
fruits, to which their appearances approximate. Indeed he candidly
acknowledges the difficulty of deciding with respect to them : and
particularly mentions two specimens, which he thought were figs,
petrified when hard and green ; being then, he thought, capable of
being impregnated with pyritical particles, which might prevent
their perishing. These, however, he afterwards found were fossils
rather deserving to be classed with the Fungoides : among which he
also places another fossil which he, at first, was inclined to consider
as a fossil fruit.

To show what caution is necessary, in admittipg as real petrifac-
tions of fruits, many of those substances which have been so de-
scribed by the earlier oryctologists, I can assure you that 1 could
have laid before you the figures of a pples, pears, plums, &c.
which would pass with many unquestioned ; but which undoubtedly
owe their forms to mere accident. In particular, I could call your
attention to a silicious stone, which not only bears the exact form
of a pear; but which has a regularly-formed depression, at the
smaller end, resembling that which would have been left on the
coming out of the stalk ; the stone, at this part, on being examined
with a glass, appearing evidently tinged with green : but that it has
not owed its origin to the fruit which it so much resembles, is, how-

441

ever, obvious, from its having no correspondent depression at the
opposite end. I might adduce other bodies, bearing a very similar
appearance, at least in their forms, with oranges, apples, figs, &c.
which have originally been of marine growth ; having been alcyonia,
sponges, and similar productions. Among these may be also placed
a silicious fossil body, resembling, on its external surface, an enor-
mously large nutmeg ; but having been cut and polished, several
lines are shown, passing like radii from the centre to the circum-
ference, yielding a very uncommon and beautiful appearance.
There appears to be very little doubt of its being the same kind of
body as is depicted by Scheuchzer, as a petrified nutmeg *.

As an additional proof of the propriety of receiving the earlier
accounts of the petrifaction of the seeds of plants, and particularly
of grain, with considerable caution, I must refer you to the fossil
represented PI. III. Fig. 6. A small specimen of this fossil is ac-
curately depicted by Swedenborg, and described as resembling a
species of Indian corn ; " Speciem praebet spies tritici Indici (mais)
dicti, nisi forma esset plana-j"."

Thus Scheuchzer also figures a fossil which he not only describes
as an ear of corn, but reasons from its figure and fulness; and
thence derives arguments in favour of his opinion that the deluge
took place in the month of May $. But Mr. Walch remarks, with
much propriety, that the body figured by Scheuchzer has much
more the appearance of a zoophyte, the rays of which are divided
by transverse lines, marking their separation into distinct vertebrae.
Of the spica secalina et graminis panici, mentioned by Dr. Richard-
son §, we can form no just opinion, as we receive no aid from either
description, or figure ; and with respect to the ear of barley, a figure

* Herbar. Diluv. Tab. XIII. Fig. 2.

t Emanuel Swedenborgii Miscellanea observata circa Res naturales, &c. pag. 15.

$ Herb. Dilur. PI. I. Fig. 1. p. 1. § Ichnograph. Lithophyl. Brit. p. 108.

VOL.I. SL

442

of which was given by Mylius*, which was repeated by Scheuchzerf ,
it obviously does not bear the proportions, nor the form, of an ear
of that kind of grain.

The bodies, whose appearances most warrant the opinion of their
having been the ears of corn, are the Stangengraupen of the Germans.
These are flat, oblong, blackish, and sometimes greenish bodies;
but becoming white, and acquiring a metallic lustre, on their pro-
minent parts, by friction. They have been supposed by many to
be mineral substances, to which mere accident has given their pre-
sent forms; but that they are really vegetable substances, which
have acquired an impregnation with metallic particles, there cannot
exist a doubt. These bodies vary very considerably in their form ;
but are generally flattened, and are studded with little round pro-
minences, bearing very much the appearance of corn, which has
been transmuted into silver. They are but very rarely found, and
are said to have been only discovered in the copper mines at Frank-
enburg, in Hesse. M. Lihman, who has written a tract expressly
on these substances, does not consider them as changed vegetable
substances ; but as being originally of mineral origin. Having sub-
jected them to a chemical analysis, he discovered that they con-
tained a small quantity of silver, with a large portion of copper,
combined with arsenic, sulphur, and iron. Wolfart has delineated
these substances with great exactness, and describes them as Spica
frumenti metallares, acknowledging himself not to be able to deter-
mine the particular species of grain from which they had origi-
nated J. By a reference to PL IX. Fig. 6 and 7> you will perceive
a representation of two of these bodies, which I have purposely
selected as throwing some additional light on this subject. The
specimen represented at Fig. 6. bears the appearance very much of
having been some species of grain in ear, or perhaps of some small

* Saxon. Subter. Memorab. p. 15. f Herb. Diluv. Tab. V. Fig. 4.

$ Histor. Nat. Hass. Infer, p. 45. Tab. V. Fig, 5 and 6.

443

cone or strobilus ; but their original mode of existence is best ascer-
tained from the appearance which is yielded by the specimen figured
at Fig. 7, where is evidently exhibited the stalk and husks from
which the grain or seeds have fallen. The width which this speci-
men possesses, making every allowance for compression, will un-
doubtedly strike you as much greater than that of any known
vegetable, the grains of which are of no larger size than those which
are represented at Fig. 6. These seeds, it may be also remarked,
differ essentially in their disposition from that which takes place in
the spikes of. the grass tribe, having much more the appearance of
that of the seeds in the strobili of coniferous plants, which seeds
they also appear to resemble in shape. 1 am, therefore, of opinion,
that we must be satisfied with considering these as fossils, whose
origin must be referred to some hitherto unknown subject of the
vegetable kingdom.

M. Jussieu discovered on a stone, which he found at St.Chaumont
en Lionnois, in the earth, near to the coal, an impression, which,
he thought, upon close inspection, and comparison with some seeds
he had received from Pondicherry, bore an exact resemblance to
the fruit-and seed of the Arbor tristis, of travellers, or the Mania
Pumeram of the Hortus Malabaricus, p. 35, mentioned also bj
Mr. Ray, in his History of Plants, p. 1698. This tree, it appears,
grows only in the Canaries, at Malabar, on the coast of Coroman-
del, and some other parts of the East Indies*.

It is a circumstance very difficult of explanation, that silicious
petrifactions of the roots of plants, or of trees (Phitolithi Radicum,
Rhizolithi) occur more unfrequently than those of any other parts
of vegetables which possess a woody hardness. Petrified roots
are indeed mentioned by some authors ; but are spoken of under
circumstances which imply their rarity. Thus Scheuchzer ha*

• Memoire de 1' Academic Royale, 1723, p. 69.

444

No. 80. Arundinis vallatorice radix*. Luid. p. ISO; but a reference
to the work of Lhwydd is fruitless, since its number of pages is
less than the number referred to ; nor do I discover the descrip-
tion of such a specimen. Langius presents us with a figure of a
Rhizolithus, of which he thus speaks : " sublutei est colons, et ra-
dicem pastinacce tenuifolice sativce radice lutea. Casp. Bauhin. Pin.
prcesefert, attains est & Toggio*^." But that the substance he thus de-
scribes was merely a figured stone, which had by some accidental
occurrence assumed the form of a piece of carrot, is most probable:
for no fact in the history of these substances is more true than the
position laid down by Wallerius, when speaking of the requisites
to be possessed by substances to render them capable of becoming
the subjects of petrifaction. " Ea," he says, " sit indole et duritia
ut non facile putrefactionem, vel aliam destructionem, subire pos-
sit, sed diutius in locis subterraneis incorrupt! bile conservari."
Linna3us also saysj, " Corpora petrificanda sint solida: testae, ossa,
ligna. Succulenta deliquescunt et corrumpuntur antequam indu-
rescant lapidosa." But even a modern author, justly celebrated
for his knowledge in chemistry and natural philosophy, speaks of
a petrified potatoe, a rhizolithus as inadmissible as that of Lang.
Argenyille, Hell wing, and others, have also described Rhizolithi;
and the last-mentioned author, not only speaks of them, in even
an agatine state, but distinguishes them into the roots of dif-
ferent trees. It must, however, be obvious, that the difference be-
tween the roots of different trees can hardly ever be such as to
allow of its being ascertained, to what kind of tree a petrified frag-
ment may have originally belonged. Thus the specimen repre-
sented at Plate II. Fig. 2. indubitably deserves to be considered as a
true Rhizolithus ; since, although it now possesses the hardness and
bears the polish of agate, its external form, as well as its general

* Appendix He^barii Diluviar i, p.70. f Historia Lapidum Figurat. Helvetia, p. 54.
| Sy sterna Naturae, torn. iii. p. 154.

445

appearance, sufficiently testifies it to have been originally the root of
a tree; bat of what tree, certainly, no judgment can be formed.
From the manner in which these bodies are spoken of, by the older
writers on these subjects, it appears to be evident, that they have
frequently referred to this head merely some of those tufaceous in-
crustations, which form round pieces of twigs and branches of wood;
and which, from their sometimes also resembling the fragment of a
bone, were generally known by the name of Osteocollce. Gesner, in
his excellent Dissertation on Petrifactions, is obviously of this opi-
nion : he says, speaking of Rhizolithi, " Hue pertinent petrificata
ramosa calcaria, arenacea, argillacea corruptarum in terra radicum
sedem occupantia, Osteocollae et Stelechita3 dicta*/' Indeed, so
much confusion has existed with respect to this substance, that
many have confounded it with the stalactite, although the truly
respectable Aldrovandus had, at that early period, fully marked
the difference. The term Rhizolithus has also been applied, by some,
to substances which have obtained their form, from the remaining
earthy particles of roots, and which, being blended with other earth,
in the mould of the decayed root, have preserved somewhat of their
original form ; but, the vegetable structure being entirely destroyed,
they can only deserve to be considered as the vegetabilia terrificata
of Wallerius.

I have hitherto supposed that bituminization was a process, to
which all vegetable matter was subjected, under certain circum-
stances; and that by this operation it became liable to the influence
of another process, that of petrification. But the absence in ge-
neral, of roots, from the collections of petrifactions, points out such
a deviation from this assumed law of nature as seems particularly
to demand investigation ; by which we may; perhaps, be enabled to
determine, whether this supposed la\v has been admitted upon false

* Joannis Gesneri Tractatus Physicus dc Petrificatis, p. 21.

446

grounds ; or whether it results from that arrangement in the ever
admirable economy of nature, by which her multifarious opera-
tions are carried on, without any injurious interference with each
other. That the latter is the case will, I trust, appear, from a slight
attention to the following observations.

No circumstance has ever been remarked which will authorize
the supposition, that vegetable matter can be liable to the bitumi-
nous change, until deprived of all the energies of vegetable life.
But roots, as is well known, long retain their vegetative powers
after entire separation from their trunk. The trunk, indeed, soon
ceases to live ; but the root will be found, after a long period, to be
alive: feeding on its own juices, and at last terminating this mode
of existence, by changing into a soft pithy substance, which soon
resolves into vegetable earth (Vegetabilia terrificata, Waller). Hence
it appears, that, after separation from the bodies which they sup-
ported, the roots of trees continue to possess those powers, which
most strongly oppose the bituminous change ; and when deprived
of these powers, they have suffered such an exhaustion of their
principles, that their resolution into almost mere earth speedily
follows.

It is observed by Liebknecht, when speaking of the ferruginous
tree found in Laubac, that, although the greatest care and industry
was employed, only very few pieces were found which had the ap-
pearance of roots ; and even these, he acknowledges, bore very few,
if any, decided marks of having originally existed in that state*.

Plate VI. Fig. 27, appears to have been part of a small branch
or twig of some tree. Fig. 29, has by some been thought to be a
spike of some grain, and by others the spine of an Echinus ; but
this, perhaps, is of the same origin as the former. The substance
represented at Fig. 28 of the same Plate, is a small silicious boulder,

• Discursus de Diluvio maxirao, &c. a Jo. Georgio Liebknecht, cap. iii. §ect. 22. p. 385.

447

rounded by attrition, being a fragment of silicious wood. It was
found in the gravel- pits at Hackney.

Fig, 15 and 17> in Plate VI. represent two specimens of a sub-
stance which is sometimes found in the chalk-pits at Cherry Hinton,
in Cambridgeshire. They have been supposed to approach very
near in resemblance to the juli of the larch-tree ; from which they
differ, however, so much in some respects, as to have induced
Dr. Parsons to have considered them, rather as the roots of a
plant, than the parts of fructification. The appearance which they
exhibit does, however, certainly support the opinion of their having
been either aments, or cones, of some tree not now known, at least,
to the European botanist ; whilst, on the other hand, the situation
in which they are found, renders this highly problematical. Instead
of being found associated with other fossil vegetables, or in matrices
which have originated in the decomposition of vegetable matter,
they have, I believe, only been found in chalk, which has proceeded
chiefly from aqueous deposition, and in part from the decomposi-
tion of animal, but certainly not of vegetable matter.

The other fossil remains of fruits on this Plate are all from that
fruitful mine of fossils, the Isle of Sheppey : and, in common with
most of the fossils obtained from this part, have so much pyrites
enter into their composition, as renders their stay in the cabinet of the
collector, in general, but very short, from their proneness to decom-
pose after having been exposed to the air. This has been the case
with the specimen represented at Fig. 5 and 7> which had evidently
been the stone of some drupaceous fruit, and which was so com-
pletely pyritous, that, .on being cut, the polished section, repre-
sented Fig. 7, shone with the most brilliant golden lustre; the
traces of its texture not being discoverable without the aid of a
lens of considerable power. Of the remaining specimens, I regret
that, although favoured by the assistance of the distinguished
botanist already mentioned, and by several other gentlemen emi-

448

nent for their knowledge of the vegetable system, I am unable to
supply you with much information respecting the plants to which
they have belonged. Fig. 2 appears to have been the seed of some
plant of the leguminous kind ; the skin of which is in part removed,
showing the fine pyritous clay with which it has beor» filled. Fig. 3
appears to have been a seed of the same kind ; the skin remaining
whole, but having wrinkled up to adapt itself to the enclosed mat-
ter. Fig 4 and 9 resemble the seeds of a phoenix; or rather of
two different species of that genus. Fig. 9 is very like to the stone
of a common date. Fig. 10 and 12, but particularly the latter,
approach very much in appearance to the common pea. Fig. 13,
14, and 18, are quite different from any thing at present known :
a portion of stalk seems to remain attached to each of them. Fig. 6,
21, and 25, appear to have been fruits covered with a coriaceous
covering, similar to the chesnut. Fig. 24 and 2(5 are fruits which
seem to have possessed a similar substance with that of the nut-
meg ; but differing very much from that fruit, in their external ap-
pearance. Fig. 20 and 22 represent the front and back view of a
substance which bears no resemblance to the parts of any known
vegetable, at least in a natural state. Dr. Smith is, however, of
opinion, that its appearance is very much like that of the cup of
aa oak, in an enlarged state, from the attacks of insects ; he hav-
ing gathered just such at Rome, in the spring of the year.

The nut which is represented at Plate VII. Fig. 1, 2, is also from
the Island of Sheppey. The exact appearance of the kernel is pre-
served in the cast formed within the shell, which is depicted at Fig.
3. It is totally unlike to any thing at present known ; but perhaps
may be referred to the genus Cocos. This fossil was originally in
the possession of Sir Joseph Banks, by whom it was presented to
the British Museum.

Fig. 4 and 5 represent part of a nut, which somewhat resembles
the former ; although the kernels vary considerably in their shape.

449

TThis fossil was added to the collection in the British Museum,
by Mr. Douglas, by whom it is figured and described in his inge-
nious Essay on the Antiquity of the Earth.

Fig. 6, 7, 8, of the same Plate represent a fossil found in Lei*
cestershire. It is of a triangular form ; three raised lines, -passing
through its length, at equal distances, on the general rounded sur-
face, give it an appearance rather difficult to imitate. Similar fos-
sils are found in Derbyshire, and have been figured and described
by Mr. Martin, in his history of the fossils of that county. Like
the fossils already described, these must also be placed among
those productions of a former world, which are unknown to us ;
and which lead to the supposition, that a considerable difference
must have existed between the subjects of the vegetable kingdom of
that period and the present. The fossil depicted at Plate IX. Fig. 2-,
is of a very dark iron-stone of a scoriaceous appearance ; bearing
very nearly the form of a lemon : but which, however, I rather con*
jecture to have been the stone of some very large drupaceousfruit.

Although from the ambiguous nature of the subjects which have
engaged our attention, we have frequently been obliged to rest
satisfied with conjectural remarks ; as yet we have been able, with-
out difficulty, to draw a line of distinction between the subjects of
the animal and of the vegetable kingdom. We now come to the
consideration of certain bodies of antediluvian origin, so equivocal
in their appearance as to render it exceedingly doubtful in which
of the two grand divisions of organized matter they should be placed.
So totally different are these bodies from any which are known to
exist in the present world, that the mind not only hesitates at
determining whether they be of animal, or vegetable nature ; but,
misled by the various fantastic forms which they assume, is disposed
to consider these several species, of perhaps the same genus, as
bodies differing so widely .from each other as sponges, figs, fun-
guses, nutmegs, and corals. It was by a substance of this kind

VOL. I. 3 M

450

that, as we have already seen, Dr. Parsons V judgment was so per-
plexed ; he at first considering that to be a petrified fig, which he
afterwards concluded to be a substance of the fungus kind. The
representation at Plate IX. Fig. 3, 4, is of a small specimen, being
one of those species of this kind of substance, which bears a resem-
blance to a small compressed fig. The upper part, Fig. 3, has a
gentle rising, as if the stalk had been attached at that part ; and
on the under surface, Fig. 4, is a similar depresssion with that which
is borne by the corresponding part of a fig. Having been able to
mark these substances under many of the various shapes they as-
sume, I have no doubt of their being of marine origin, and the
residence, and perhaps the workmanship, of animals : they would
not, therefore, have been mentioned in this part of our inquiry,
but for the sake of showing you that we have now arrived at the
examination of substances which, though apparently of a vegetable,
are really of an animal nature; and that we have therefore reached
the line at which our present labours should cease.

HAVING now furnished you with what information is in my
power respecting real petrifactions of vegetable substances ; it be-
comes necessary to say a few words respecting those stones which,
from* their accidentally possessing the forms of certain parts of ve-
getables, have been by many supposed to have actually derived
their figures from the substances which they so much resemble.
These stones, the Phytoglyphi of Wallerius, being a species of the
Petrificata ficta of Linnaeus, Lithoglyphi of Wallerius, and Lapides
Jigurati of others, have, from their great similitude to different parts
of vegetables, occasioned numerous mistakes in the writings of

451

the earlier oryctologists. From circumstances which affect the for-
mation of stones, they are more likely to be disposed to assume the
oval or globular forms of seeds and fruits than of any other parts
of vegetables. To such, therefore, our present consideration will
be chiefly directed.

Among those figured stones which have obtained the greatest
celebrity, from their resemblance to fruits, are the melons of Mount
Carmel. Melopeponites, Aldrovandi. These are crystalline geodes
which not unfrequently bear the forms of melons and other fruits:
the rounded, granular-formed crystals having been supposed to re<-
semble the seed, and credulity having sometimes gone so far as to
fancy, that the smell of the fruit was yet discoverable in its supposed
petrified remains. One of these petrified melons of Mount Carmel,
of a small size, and opened, is represented in Plate IX. Fig. 5.
The bare-footed friars of Mount Carmel have chiefly contributed
to the fame which these substances have acquired, they having, by
the aid of an old legendary tale, been able to render them an article
of profit to themselves, and of great curiosity with travellers, who
have resorted to Palestine. On this mount there is a particular
spot, which is termed the field of melons, where these bodies used
frequently to be found ; but which of late appears to have been
exhausted, by the traffic of preceding years. The legend says, " On
this spot was a garden-ground, well stocked with melons ; and that
the prophet Elias, the founder of the monastery, once asking the gar-
dener for one of his melons, he, with churlish humour, answered, that
they were not melons, but stones ; 'on which they were immediately
changed to stones, and have so remained to the present day." But,
according to the industrious friars of the order of Elias, the punish-
ment of the gardener's pertness did not rest here ; since they fur-
nish travellers with other fruits, which, happening to be in the same
garden, shared the same fate ; thus we have the Pomum crystallinum,
&c. For the mode in which this extraordinary miracle was per-

452

formed I must refer you to a former Letter*, not thinking it neces-
sary to pause any longer here, in removing any doubts which scep-
ticism may have suggested.

Similar tales have been invented, for the purpose of accounting
for other stones which have borne the similitude of vetches, of
pease, &c. Thus the Virgin is said, in passing from Bethlehem to
Jerusalem, to have beheld some peasants who were sowing pease,
and begged they would present her with some, which they refused,
saying they were merely stones : — Then such, she replied, shall you
reap ; and since then, it is said, nothing will grow there except
these stones, which possess the form of pease. For the better un-
derstanding of this miraculous transmutation 1 must again refer
you to a former Letter-)- ; and when I inform you that these petri-
fied peas are formed of a calcareous stone, of a yellowish white
hue, and frequently irregular in their forms, you will with very
little hesitation believe that their origin is similar to that of the
Confetto di Tivoli which are there described. I need hardly re-
mind you that immense quantities of stone exist in different parts,
formed of similar round bodies, which are termed Pisolithi, ori-
ginating in stalactitic concretion. When these concretions assume
a smaller form, they have been termed Meconites, or Cenchrites,
according as they most resemble the seeds of the poppy or of
the millet. When the mass has resembled a collection of the
grains of wheat, &c. it has been termed Lapis frumentarius, and it
has been considered as the petrifaction of such grain.

But one of the most curious of the suppositions petrifactions of
vegetable matter is petrified bread (lapides paniformes — panes pe-
trifacti, seu dcemonis. Teufel Brod.) Bruckman gives a very par-
ticular account of different petrifactions which had been supposed
to have been of this kind,

• Letter XXXII. t Letter XXXIX,

453

In the church of St. Peter, of Leyden, a stone is preserved, the
history of which is, that— in the year 1316, a poor woman, deserted
by fortune, and almost perishing, with her numerous children, for
tfant, humbly petitioned her rich sister for bread. She, however,
refused to supply her, and swore, in the most solemn manner, that
she had no bread in the house; which the other doubting, she
added, if there were, might God turn it into stone ! an.d directly,
to her astonishment and horror, the bread became stone. An au-
thor, of the name of Hartnoch, also relates as wonderful a story.
A poor woman, oppressed by misery and want, was passing along,
with one child in her arms, and another following at her heels,
all nearly perishing with hunger, it being in the time of famine.
They met a brother of the holy order of St. James. She implored
him, for the mercy of God, to spare her a morsel of bread for her-
self and almost famished children : the hard-hearted wretch most
solemnly assured her that he had no bread ; but the woman directly
replied, that she saw he had a loaf in his bosom. This the holy
brother denied, saying that it was a stone which he thus carried,
to defend himself from the dogs. Soon after this he put the loaf
to his mouth, with intention to eat of it, when he found that it
was no longer a loaf, but a complete stone. Struck with horror,
he repaired to the monastery, confessed every particular of his
crime, and the wonderful judgment : in commemoration of which,
our author says, the petrified loaf was hung up in the chapel of
the monastery. We also learn, that at Schemnitz, in Hungary,
a woman, despising the sacred institutions, was making bread on
the feast of St. Anne, when she found that all her loaves were
become stones, whilst in the oven. The learned Bruckman men-
tions other instances of these miraculous conversions, and particu-
larizes several places where specimens of stones bearing the appear-
ance of petrified bread may be seen ; concluding with the following
appropriate ejaculation,

454

Da nobis panem, Domine f in diebus nostris ; non durum et la-
pideum, sed frugalem ac sufficientem.

I should not have thus introduced, in our examination of the
petrification of vegetable matter, the mention of petrified loaves,
but for the sake of observing, that, of all the sports of nature, in
the formation of stones, these are among the most delusive, and
unaccountable; judging from a specimen in my possession, which
I understand was obtained by the late Mr. Strange, from Germany,
at considerable trouble and expense. Its form is that of a long
square, being similar to what are generally called Dutch loaves. Its
upper surface is rounded, and of a dark brown, exactly agreeing in
shape and colour to the upper crust of such a loaf; whilst its oppo-
site surface is flattened, and of a paler brown; bearing as perfect an
agreement with the under crust : both the one and the other pos-
sessing the smooth surface of the crust of a loaf. The intermediate
substance, answerable to the crumb, possesses, in an extraordinary
manner, the rough spongy appearance of the crumb of bread, be-
ing even separated by such clefts as might be supposed to have
taken place in bread which had been dried by long keeping. The
substance of the stone appears to the naked eye like a coarse jas-
per ; but on a close examination, with the aid of a glass, the inter-
nal substance is discovered to be formed of very small white sili-
cious stones, agglutinated by a silicious medium ; and the external
part of brown silicious stones, connected in a similar manner : the
substance of our seeming petrified loaf turning out to be actually a
plum-pudding stone formed in some cavity, most probably left by
the decomposition of some substance ; ,but what this substance had
been it seems impossible to ascertain. The late truly respectable
Dr. Gray, of the British Museum, thought it not improbable that
this stone had formed part of the nucleus of an immensely large
solen.

The substances represented at Plate IX. Fig. 8 and 9, have ob-

455

tained the name of petrified mushrooms : nor could the petrifaction
of funguses produce a nearer resemblance to mushrooms than these
substances present. They are frequently found in the cliffs in Dor-
setshire, and other parts, and appear to have been formed by the
gradual oozing of a soft ferruginous clay, strongly impregnated with
pyrites, from small openings in the rocks.

Yours, &c.

LETTER XLVIIL

CONCLUSION.

ENDEAVOURED, in the early part of our correspondence, to lay
before you the opinions which were formerly entertained, respect-
ing the substances which have been generally known by the name
of extraneous fossils ; and also to give you a slight sketch of the
history of the discoveries which have been made, concerning their
nature and origin, we then entered upon an examination of such
substances as appeared to be best designated by the term vege-
table secondary fossils. A strict examination of these seemed to
render it manifest, that their formation depended on a certain law
of nature which decrees, that such vegetable substances as become
buried so deep, as to prevent their being directly useful to man,
either as timber, or as soil fitted to aid the growth of other vege-
tables, should undergo certain other changes, by which they should be

456

rendered peculiarly fitted for supporting combustion, in the various
modes necessary for promoting the comforts of mankind, and con-
ducting the numerous arts of civilized life.

In this new mode of existence we saw reason for supposing, that
the combination which took place was such as to resist the decom-
posing powers of almost every agent, except that of fire : manifesting
the completion of the process, and evincing proofs of the most wise
and providential arrangement. For here we perceived that a state of
permanency was yielded to the substance thus formed ; which sub-
stance appeared to be intended for the use of man for a period of
time, not only beyond our knowledge, but even beyond the reach
of conjecture. On the degree of perfection to which this process
attained, and on the introduction of various earthy, and other
matters, appeared to depend the formation of the different kinds
of bituminous substances, and particularly the different varieties
of coal.

There also appeared great reason for supposing that, in some
situations, and under certain circumstances, this process was ar-
rested, in small detached masses, b^ their being subjected to parti-
cular saline, earthy, or metallic impregnations. In which cases it
was presumed, that substances were formed, which, although not so
useful to man as those already mentioned, were well calculated to
increase his number of elegant luxuries, and to excite in his mind
the highest degree of admiration, by their extraordinary, and often ex-
quisitely beautiful appearances. Thus seemed to have been formed
the fossil woods; some, at least, of the jaspers ; the pitch-stones;
the wax, or serni-opals ; and, perhaps, even the noble opal itself.

The most direct inferences, from obvious facts, made, whilst
considering the nature of those bodies, which have been the sub-
jects of our correspondence, lead to the conclusion, that, indepen-
dent of the accomplishment of any other important purpose, by
the resolution of a former world, one grand object appears to have

457

been attained — such an arangement and modification of the seem-
ing ruin, as produced the regeneration of a world, stored, in its
deepest recesses, with substances calculated to promote the comfort
of man ; to tempt him to the exercise of his innate powers ; to fur-
nish him with the means of supporting his dominion over the ani-
mals around him; and even to urge him to a change from the
savage to a civilized state. Another world rises from the over-

o

whelming flood, composed of the fragments of the former, which
appear to be blended together, in an apparently disordered and
incongruous mass. But, after the lapse of a small period of time,
the constituent parts of the newly-formed world are discovered to be
arranged, according to those wise laws which the great Creator had
decreed from the beginning. The surface again teems with beings
possessed of the energies of animal and vegetable life ; and after
ages discover, that the atoms of which the new world is formed,
acting reciprocally on each other, with varying, but appropriate in-
fluence, regulated by the laws of attraction, and chemical affinity,
compose a variety of new combinations; and the newly-formed
world, enriched by the amelioration of its materials, obtains an in-
crease both of utility and beauty.

This circumstance, which I consider as plainly pointing out the
wisdom and power of the Creator, may, however, I am perfectly
aware, afford occasion for hesitation to the sceptic, who may ima-
gine that the necessity of forming the world anew implies that its
first formation was deficient in design. But considering this planet
itself, as probably destined, with the other works of creation > to
undergo certain regular changes in its constitution, during the

^wfe

progress of its existence, such changes cannot furnish sufficient
grounds, for doubting of the wisdom or power of God : not even
were it discoverable, that this world had undergone several revo-
lutions and reformations ; and that, in common language, several;
VOL. i. 3 M

458

worlds had existed before the present. Man, unable to view the
connection between these changes, and to judge of the important
ends, intended to be thus accomplished, would show as much
folly and presumption, by inferring a narrow limitation of the
power of the Creator, on discovering that the remains of former
worlds entered into the composition of this, as if he were to make
a similar inference, on remarking one of the metamorphoses of the
silk-worm, without being acquainted with the other particular cir-
cumstances in the natural history of that insect.

Regarding the destruction and renovation of the world in this
point of view, the most interesting conjectures force themselves on
the mind. If it be apparent that, from the breaking up of a pre-
ceding world, the present has derived a higher degree of utility
and beauty ; may not this also be preparing to undergo, at some
distant era, a new recomposition, by which it may be made to ex-
ceed this, in a similar proportion, in the possession of every excel-
lence ? May it not thus become fitted for the reception of beings
of higher susceptibilities and powers ? — But, checking this propen-
sity to indulge in vain, and, perhaps, dangerous conjectures, we will
return to inquiries rather more within the reach of reason ; pre-
mising only one observation, intended, to render more striking the
necessity of diffident caution, whilst employing our limited powers of
judgment, on any point which involves the knotty question of the
origin of evil. How derogatory from the dignity and omnipotence
of the Creator, might a presumptuous and short-sighted caviller say,
is the unfinished condition of great part of the creation, requiring
the aid of art to effect the full evolution of its powers ? — not a plant,
nor an animal, is there scarcely which exists, but, in its natural state,
is so far from perfection, as to require the greatest care and culture,
to procure the full display of its beauties, and the developement of
its various faculties. But, one more glance is sufficient to discover,

459

that this apparent deficiency of power and judgment is a remark-
able instance of the wisest adaptation of means to the producing
of a most important end. For when it is cosidered, that the domi-
nion of the earth is given to a being, endued with peculiar faculties,
the preservation and improvement of which depend on their due
exercise, it surely is not discordant with the correctest ideas of an
arrangement, proceeding from consummate wisdom, and unlimited
power, thus to furnish that being with materials on which his abili-
ties may be employed.

On examining those vegetable remains which still displayed some
traces of their original forms, appearances were discovered, which
seemed to point out a great dissimilarity between some of the vege-
tables of the former, and of the present world. So great did this
dissimilarity appear, as to warrant the conclusion, that either many
genera and species of vegetables, which existed in the former world,
are now entirely lost, or remain secreted from us in some remote, and
hitherto unexplored part of the world. Reasoning by analogy, from
the undoubted loss of several species, and even genera of animals,
we are led to consider the loss of a part of the vegetable creation
as far from improbable. This is a point which cannot, however,
be said to be determined, whilst any part of the world, in which
they may be concealed, has escaped the examination of the bota-
nist ; especially as some very good and learned men have regarded
the loss of a single link, in the chain of creation, as inadmissible ; it
implying, they say, such a deviation from the first plan of creation,
as might be attributed to a failure in the original design. But such
an inference does by no means follow ; since that plan, which pre-
vents the failure of a genus, or species from disturbing the general
arrangement, and economy, of the system, must manifest as great a
display of wisdom and power, as could any fancied chain of beings,

460

in which the loss of a single link would prove the destruction of the
whole.

During the progress of our inquiries, one fact was discovered,
which demands our particular notice, in this place. During the
numerous explorements of the strata containing the remains of
those substances, which existed in the world before the flood,
not a single antediluvian piece of art has been ever found. This
circumstance, alone, constitutes an argument of no small force
against the eternity, at least, of the existence of man ; since had
the earth, peopled by mankind, existed eternally, the number of
human beings which would have existed at the time of the deluge,
would have been so great, and their spread over the face of the
earth would have been so general, that their weapons,, their various
utensils, and articles of furniture, must necessarily have been fre-
quently discovered among the antediluvian remains. This circum-
stance, it must, however, be admitted, appears to prove too much ;
since, as none of the remains of the labours of man have been thus
discovered, we are without a proof of the existence of any human
beings, at the time of the deluge ; and therefore have more reason
to suppose, that man had not been created, at the period, at which
this event occurred, than that the whole species, excepting a very
few individuals, were destroyed with it.

Why the earth was at first so constituted that the deluge should
be rendered necessary — why the earth could not have been at first
stored, with all those substances, and endued with all those pro-
perties, which seem to have proceeded from the deluge- — why so
many beings were created, as it appears, for the purpose of being
destroyed — are questions which I presume not to answer. Trusting,
that what has already been said must render their solution less diffi-
cult, and lead to conclusions less repugnant to reason, than some

461

which have been advanced, by men of cbnsiderable abilities, and
learning, I shall here close our correspondence, for the present, ex-
periencing no small degree ef satisfaction at finding every fact I
have noticed, and every conclusion which they have led me to
make, to be in perfect accordance with the highest sentiments
which can be formed respecting those laws, by which the regula-
tion of the economy of creation was decreed.

Yours, &c.

END OF THE FIRST VOLUME*

i\:hinl..i In .1 r.utm»vi Hour* Jmu ilt,'l

/•/. 1

flMl/1,1 hi .1 1'all.in ii -n il. rl,;, lull, I

PL. \I

irM *r JFlHanl.ltllna-n.Jur i.ltn

/'/.. I'//.

th.l ••

Mil

v../\

» »

« , » ' ' •

INDEX.

Page

ACORN, fossil 439

/Elites, formation of 318

Agricola, treats of secondary fossils 19

Albert le Grand, mentions a petrified branch

of a tree, with a bird's nest and birds 18

Alder, petrified 393

Alexander ab Alexandra, speaks of secondary

fossils 17

Amber, analysis of 154

containing extraneous bodies 151

described 150

• • known to the ancients 150

• produced by the bituminous fermen-
tation 223

Analysis of bituminous spar 378

. calcareous wood 377

— jasperized wood 335

opaline wood 348

Ash, petrified 393

Asphaltum 121

analysis of 148

— mine of, in the Isle of Bua 142

mentation

- produced by the bituminous fer-

219

Beech tree, petrified 893

Beringer (Dr.) duped by factitious represen-
tation of petrifactions 26

Bitumens, described 129

— frequently found in Derbyshire... 146

— • mentioned by the most ancient

writers ].'40

treated of by more modern authors 138

the result of a peculiar fermenta-
tion 207

Box tree, petrified 3Q3

Bread, petrified 462

Bucket, petrified .197

Cannel-coal, described 157

its difference from jet explained 232

Caoutchouc, mineral, or elastic bitumen ...... 1 29

Caoutchouc, mineral, found in Derbyshire... 146
. varieties of 147

Casts described 37

Caverns, stalactitic, described ; 372

Charcoal, mineral, described 275

found in various parts 280

formation explained 286

-1 opinions respecting 273

Charmouth cliffs, slow combustion of 278

Chemnitz, starry stones of 401

Cherry-stone, fossil 439

Coal, accompanied by pyrites 177

analysis of 178

cause of particularities 263

described I5f

how produced by the deluge 269

— long known in China 16J

not often mentioned by Greek writers,

or early Romans 162

opinions respecting the formation of ... 233

opinion respecting, proposed....... 247

— — peculiar arrangement of the particles of 264

strata belonging to .... 168

varieties of 160

Kilkenny 27S

pits, combustion of 170

general observations respecting ... 17 1

particularities of 173

explained 261

Cocos, petrifactions resembling nuts of that

genus 448

Coffee-berries, fossil 439

Confetto di Tivbli 363

Corn, ears of, fossil 441

Cup of the oak 44»

Date stone 448

Deluge, effects of, conjectured 251

universality of the, asserted 251

opposed 250

Dice, fossil , 400

Eagle stone. See Elites.

Earths described 43 Sf seq.

En hydros, formation of §18

Eratosthenes notices secondary fossils ...... 15

Fermentation, bituminous 179

. . acts chiefly on the

ligneous substance , 216

i — — — compared with the

other fermentations , 132

i imitates the result

INDEX.

Page

of secretion 209

observations on ... 181

• — produces peat .... 187

produces the purer

bitumens 209, 218

Fir, petrified S91

Flint, common, observation? on 358

— ' • containing fossil wood in its centre 362

Flowers, fossil 436

in a flint 437

• • six feet underground 438

Fossils (secondary), ancient writers on .. 15 # seq.
ancientopinionsconcern-

ing 30 # st<j-

' divided into vegetable

and animal 36

• (vegetable, secondary), division of... 52
Fracastorius'sopinion respecting petrifactions 1 9
Fruits, fossil 438

Gate of Hell 326

Geode, formation of. 317

Hammer handles, petrified 396

Hatchett, Mr. his excellent remarks on the

bitumens referred to 219, '220, 221

Hay, mow-burnt 193

Hazel tree, petrified

Herodotus speaks of secondary fossils 15

Honey-stone. See Mellite.

Hura, fruitof, fossil 439

Impressions, described 37

vegetable 391

Incrustations, described , 37

Iron-stone, vegetable impressions on 398

Islands, floating ,... 196

Jasper, proceeding from vegetable decom-
position 334i

Jet, described jtt

— - mentioned by ancient writers 155

opinion respecting its origin ,. 229

transition into cannel-coal .

Kinson pool, floating islands there 199

Ladder, petrified > -J^Q

Lake of mineral tar, in the island of Trinidad 143

Lapis Sarnius, described .... t 3^^

Larch tree, petrified rti w 393

supposed;/!*/; petrified 447

Laurel tree, petrified 3gg

Leaves, impressions of. t 4,^

•• in nodules 414,431

— — •"". • •• accounted

for 432

Lime, mode of its impregnating fossil wood. 373

Lindeu tree, petrified _ 30.4

Loaves, petrified ,t> ^ 4.54,

Lough Neagh, petrified wood of 57, 343

Maltha. See Pitch, mineral.

Matlock, incrusting waters ^QQ

Medals, formed of Tufa

Mellite, described p 228

origin of, considered 229

Melons of Mount Carmel 322 451

" — formation of. 322

Mountains, primary, contain no secondary
fossils.....

secondary, frequently contain

secondary fossils

Mulberry tree, petrified

Mushrooms, petrified

40

Naphtha

a product of the bituminous fer-
mentation ..

393
454

127

219

chemical properties of 14.7

T • found in various parts of Russia... 144

._ at Pitchford, in Shropshire . 146

Nodules, agatine, formation of. 326

argillaceous, containing vegetables

414,

INDEX.

Nodules, of iron-stone 428,439

Nutmeg, supposed fossil 438

Oak, petrified 393

Oculus mundi. See Opal, hydrophauous.

Opal, analysis of 353

described 365

hydrophanous 357

analysis of 357

Ostcocolla. See Syringites.

Peas, petrified 452

Peat, analysis of 137

described 85

• found in various parts of the world ... 88

England 91

observations on, by various authors ...
opinions respecting the origin of

87
97

- origin of, different opinions respecting. 187
-- opinion respecting, by Dr.

Anderson ....................................... 199

- 'produced by the bituminous fermenta-
tion ........................................... ... 186

— — spontaneous combustion of. ........ . ..... 193

Pebbles, silicious ................................. 311

- contained in Bamboo cane. 3'27

- - - observations on the forma-
tion of .... ....................................... 311

Pepys,Mr.hisexaminationof jasperized wood 33 I

- --- his analysis of opaline wood ...... 34.7

Petrifactions ....................................... 296

-- accounted for by Professor Play-

fair .............................................. 303

- another theory of, proposed .... 306

- - - calcareous, of New South Wales 381

- explanation i>f, by Dr. Hutton... 300
-- Vide Fossils (secondarv)
-- improper as a general term ...... 33

-- prot eeiling from bi;uminization 307
--- supposed to be formed by sub-

stitution .......................................... 297

-- th- -feting ............... 296

Petroleum .......................................... 128

- - analysis of ............................ 143

- ipriaga ia Modeoa .................. l k;

--- ia Coa)hrook-<lale ... ..... 1 J-7

wells of, in the Burniha dominions 143

VOL. I.

flfi

Piles, oak, said to be petrified 395

Pipe-stone 402

Pitch, mineral 128

a product of the bituminous

fermentation .219

Pitch-stone, common 346

analysis of, by Mr.Pepys 348

.- by Mr.Klap-

roth . .351

• . ligniform 345

Pliny gave name to many secondary fossils . 16

Plum-stone fossil 438

Potatoe, supposed petrifaction of 444

Pyrites, formation of, explained by Dr. Hut-
ton and Mr. Playfair 284

opinion respecting 286

spontaneous combustion of 297

Quarries of Travertin 380

Reed, petrified 426

Root of carrot, petrified 444

Roots, petrified 443

rarely found 455

Sandal tree, petrified 393

Sandal-box, fossil 439

Sapindus, berry of, fossil 439

Schisti, vegetable impressions on 446

Seeds, fossil 437

Semi-opal 3J3

remarks on Mr. Klaproth's exami-
nation of 354

Shepey Island, fossils of 439,447

Siberia, metallized wood of. , 388

•At

Silex, contained in water.%7. 324

1 forming tufa 326

• * forming stalactitic concretions 327

in the rind of cane 327

Shu s of coals, vegetable impressions on...... 420

Spar, buuminoui 379

Stangtngraupen 442

Starry-stone of Chemnitz 401

Steins of plants, petrified 423

St me, Sarnian. See Lapis Sarnius.

shaped like a human thigh, wonder-

ful tale of
3 N

INDEX:.

Page

Stones (figured) , 39, 449

in plants and trees 327

- of fruits, fossil 437

Strabo speaks of secondary fossils 15

Strata, accompanying coal 166

Strobilus 428,442

Swedenborg, mistake of 441

Syringites, described 369

Tar, mineral 128

a product of the bituminous fer-
mentation 219

lake of, in the Isle of Trinidad. 140

Teredo navalis, wood eaten by, petrified 407

Tertullian speaks of secondary fossils 15

Theophrastus wrote on petrifactions 15

Thunderbolts, supposed 399

Tiburtine, described 371

Tiverone, waters of 365

Travertin, described 371

Trees, fossil, in the Isle of Anglesey 57

known in remote periods 53

mentioned by variousauthors54 fy seq.

— . rendered bituminous 189

Tufa, silicious, of the Geyser 325

Umbria, fossil wood of. 101

Vegetable mould 81

Vegetables, constituents of 72

first step to the mineralization of 80

— . food of 76

fossil, difficulty of ascertaining

their kind 416

impressions of 412

resolution of, into their first prin-

ciples 79

Velino, lake of 365

Velinus, cataracts of 366

Vine, petrified , 393

Walnut, fossil 438,439

Waters, incrustating....> 361

of England 36J

of Italy, &c 363

Waters, silicious 322

of Bath... . 324

Page

Waters, silicious, of Carlsbad 324

of Iceland 324

Willow, petrified 393

Wood, bituminous 102

of Bovey, near Exeter,

described by Dr. Milles 109

the present

state of, described ............... . .............. 125

— of Germany, described

by Hollman .................................... 105

• silicized ................... 330

. treated of by various au-

thors

Wood, eaten by ship-worm, petrified ......... 416

- fossil, at Sutton, in Lincolnshire ..... 68

--- dug up in various parts of Eng-

land ............................................. 60

---- impregnated with copper ...... 388

— — ----- iron ......... 384

----- silver ....... 390

--- mentioned by various authors . 54

---- metallic fossil wood ............ 384

Wood, petrified, agatrne 333

aluminous 383

— • calcareous from Bath 375

Charmouth 375

Oxfordsh... 375

• chemical ana-

lysis of 377

calcedonic 331

jasperized : 333

chemical exami-

nation of 334,

— opaline 337

chemical examina-

tion of 347

' silicious 330

• wonderful nature of 50

Wood, pyritous 282

formation of 289

World, antediluvian, abounding in vegetables 252

Xanthus of Lydia speaks of secondary fossils 15
Xenophanes mentions secondary fossils...... 15

Yew, petrified 65

78

RETURN TO DESK FROM WHICH BORROWED

FAtttft SCIENCES LIBRARY
TEL: 642-2997

This book is due on the last date stamped below, or
on the date to which renewed.
Renewed books are subject to immediate recall.

MftfH44S2O_

^coxsaz*

j/c_-LJ^

^%i^r IJIBJJ

1

OCT 0 2 2005

T-n ni tn i 'ca General Library
LD 21-40»i-l 68 University of California
(H7452slO)476 Berkelev