September 4, 1914.

THE COLLIERY GUARDIAN.

517

killed by falls, or 5-60 per 10,000 employed below
ground; 30 persons were killed in haulage roads and
inclined places, 19 in shafts, 7 by explosives, and 8 by
firedamp. The latter, it is interesting to note, were all
cases of asphyxiation; only one ignition of firedamp,
followed by injury, occurred, six workmen being slightly
burnt by the ignition of firedamp in a sinking shaft, the
cause being an ordinary electric lamp on a circuit,
employed on conditions contrary to the regulations.

Generally speaking, Belgian mines compare favour-
ably from the point of view of safety with those of any
other country.

The charts which are given herewith show the allo-
cation of the industry in Belgium. Fig. 1, compiled by
M. Armand Renier, for the Toronto Geological Con-
gress, shows the geological characteristics of the various
coalfields. Figs. 2, 3, and 4 show the position of the
most important collieries in the Liege, Charleroi, Centre,
and Mons coalfields respectively.

DIRECTIONS FOR THE COLLECTION OF
GEOLOGICAL SPECIMENS *

By John William Evans, LL.B. D.Sc. F.G.S.

Introductory.—There is no study in which there are
so many opportunities for local workers or such need of
their assistance as in geology. Everywhere there are
special problems to be solved, and any spot may furnish
information which will throw much needed light on the
geology of a whole district. The main purpose of this
publication is to give such directions as will secure that
the specimens are properly selected, that their source
is sufficiently identified, and that they are packed so as
to suffer as little injury as possible in transport.

Rocks, Minerals, and Fossils.—The specimens which
should form part of a representative geological collection
of a district are usually classed under the headings of
“ rocks,” “ minerals,” and “ fossils.” “ Rock ” may
include any material which forms a considerable portion
of the earth’s crust, whether it be hard and tough like
granite, soft like clay, or as incoherent as sand.

The word “ mineral ” on the other hand is restricted
by the geologist to a substance of definite chemical com-
position and characteristic physical properties.

By miners, however, the term “ mineral ” is used in
the more general sense of anything of economic value
obtained by mining operations from the earth’s crust.
Thus coal would be considered as a mineral from their
point of view, though scientifically it has no claim to
the title; but products employed for building or road-
making, such as granite, sandstone, limestone, gravel,
sand, and clay are not as a rule referred to as minerals
even by the miner.

Under “fossils” are comprised all remains of plant or
animals, including, for instance, stems, leaves, shells,
and bones, as well as mere indications, such as foot-
prints, of the former existence of a living organism.
Fossils are frequently of the greatest value in determin-
ing the relations of the rocks in which they occur and
the geological structure of the country.

What to Collect.—The collector should endeavour so
far as possible to obtain specimens of all the different
types of rock that are met with in the area which is
the scene of his operations, as well as of the minerals and
fossils associated with them.

In the case of intrusive rocks, any variations of tex-
ture or composition should be represented in the
collection. In particular, specimens should be obtained
not only from the centre of dykes or sills, but from their
margins, where they are in contact with other rocks.
Specimens from the margins of massive intrusions are
equally important.

Small specimens of economic mineral products are of
comparatively little use. Seven pounds weight at least
of ore or coal should be obtained. It should represent
an average sample of material that could be obtained in
commercial quantities.

It may be laid down as a general rule that, if rocks or
minerals are unusually heavy, that is to say, have a
specific gravity of over 3|, specimens of them should be
taken as a matter of course, for they may prove of value
for their metallic contents.

Breaking Off Specimens.—A geological hammer should
be employed for taking specimens of hard rocks. The
head should be of tough steel, not too highly tempered,
and weigh from 1 to 1| lb. A heavier hammer weigh-
ing 3 or 4 lb. is useful in the case of really tough rocks,
and arrangements should be made to have it at hand
when needed. The head of the hammer should be
square in shape at the front or striking end, and it
should be prolonged at the back to a chisel edge, which
should be at right angles to the handle, but there should
be no bevel on the underside, that is to say, the side
from which the handle projects. In the case of a heavy
hammer, however, the chisel edge should be parallel to
the handle, and have a short bevel on both sides.

In striking off a fragment the hammer is held loosely
while it is being swung and when the blow is delivered.
The effect of the concussion is, therefore, due to the
momentum of the head, not to force directly exercised
by the arm. The rock should be struck evenly by one
of the rectangular edges of the front of the hammer.
.With heavy hammers the edge will sometimes break
with the shock. To avoid this, some geologists strike
with the whole front face of a large hammer, and this
is in many cases quite as effective as a blow with the
edge.

It is usual to trim a sample so as to measure about

* Extracted from an official publication printed under the
authority of H.M. Stationery Office.

4| in. by 3 in. by 1 in., or 3 in. by 2 in. by f in. For
this purpose a small hammer, the head of which weighs
about 4 oz., is employed. Portions of the weathered
surface, or of the walls of joints or fissures, are usually
removed. Where, however, the weathered surface is
very characteristic it is convenient to leave a small por-
tion adhering to the specimen, unless, of course, a
separate specimen of the weathering be taken. It is
important to avoid giving a battered appearance to the
specimen, and the shape should be obtained by striking
off splinters, and not by hammering down projections.

Besides the hammer or hammers, two or three cold
steel chisels 4 or 5 in. long are useful for getting out
minerals and fossils.

Wrapping Up and Packing. — It is of the greatest
importance that specimens should be properly protected
from injury, and that each should carry with it unequi-
vocal evidence of the locality where it was collected.

Cotton, linen, or manilia bags are sometimes used
instead of paper, and may have a distinguishing number
printed on the outside. This, however, is easily obli-
terated with rough usage. A better plan is for the
number to be engraved on a metal disc with a perfora-
tion by which it is threaded on the string employed to
tie up the bag. In any case a folded slip of paper, with
the particulars already mentioned, should be placed in
the bag, which should be sewn up or tied round with
string close to the specimen so that the latter cannot
shift its position.

Fossils.—In collecting fossils it is obviously desirable
that they should include as many different forms, and be
in as perfect condition as is possible. The exact bed in
which each occurs should be ascertained and recorded,
and if there are several fossiliferous bands the fossils
from each should be clearly distinguished. For this
purpose it is sometimes useful to have a number of bags
suspended from a belt round the waist so that all the
specimens from the same bed may be placed as they are
collected in the same bag. If the haversack is divided
up into separate compartments these will serve the same
purpose. Care should also be taken to distinguish
between fossils belonging to the stratified rocks them-
selves and those found in fissures in them filled with
later material, which has entered from above, but has
in many cases consolidated to form hard rock. Such
occurrences are frequent in limestones.

In slates, fossils are rarely well seen on the cleavage
face unless it happens to coincide with the bedding.
Where this is not the case, search should be made for
the true bedding planes, and efforts should be made to
break the rock along these across the cleavage. It is on
the fractures thus obtained that there is the best chance
of finding fossils.

As a general rule fossils are difficult to detect in com-
pact limestones, except on a weathered surface such as
is lound in clitts, old quarry faces, and masonry. {Special
attention ought to be paid to concretionary nodules
which should be carefully split open to ascertain if they
contain fossils. Sometimes the best results are obtained
by first breaking them across the bedding and then split-
ting them along it. Calcareous nodules in clays and
shales may include shells and fish remains, while iron-
stone concretions in coal yield well-preserved plant frag-
ments.

.Limestones frequently contain siliceous concretions,
of which flints are the most familiar example. These
afford not only organic remains which were originally
siliceous, but calcareous and other organisms which have
been converted into silica. When the interior is hollow
it usually contains fine siliceous powder which consists
of minute organisms such as sponge spicules. Where a
limestone has been exposed to weathering and solution,
remains of silicified organisms derived from it may
frequently be found in the cultivated fields above it, and
in many desert areas siliceous concretions and silicified
fossils scattered over the ground are the only evidence
of thick beds of limestone which have been removed
by the action of the wind. Calcareous organisms which
occur in soft, easily weathered shale are in like mannar
found on the surface of arable land.

Phosphatic nodules, which are met with in limestones
and other beds, also frequently contain fossils. Small
fossils present in loose material may usually be sepa-
rated by some kind of mechanical treatment, for
instance, by using sieves of different mesh, by the attrac-
tion of electrified ebonite and amber, or by employing
water or heavy liquids in the manner described below in
the treatment of sands.

As a general rule no attempt should be made to clean
fossils or remove them from the matrix except so far as
may be absolutely necessary to reduce the specimen to
a portable size. At the same time the nature of the
matrix in which the fossil was found will be recorded
in the most unequivocal manner. Any separation of
one portion of a fossil from another should be, if pos-
sible, avoided.

When a specimen, on account either of its size or of
its condition, has to be divided into two or more por-
tions, whether these are separate bones of a skeleton or
parts of the same object, it should be carefully sketched,
and, if possible, photographed, before it is disturbed.

Sometimes hollows or “ casts ” are found, represent-
ing the space formerly occupied by a fossil which has
been removed. In such cases a portion of the rock
sufficiently large to include the entire cavity should be
taken, so that a cast may ultimately be made of it.

Where a specimen is too heavy or friable to be moved,
a cast may be made of it on the spot. Internal casts
may be obtained by filling the cavity with a mixture of
gelatine and glycerine in such proportions that it is
liquid at a temperature a little below that of boiling
water, and is solid at ordinary temperature. It is
poured in when hot, and when it has solidified the rock
is carefully removed from round it. Plaster of paris
may be employed for external casts. It should be
fairly liquid when applied, and the rock should have
been previously coated with soft soap or a thick lather or

oil. An external cast may also be made by repeated
application of thin absorbent paper soaked in starch
paste.

The impression or counterpart of a fossil should always
be preserved, as it may assist materially in the interpre-
tation of the fossil, and even afford evidence of addi-
tional features. Sometimes between a fossil and its
counterpart there is a shallow space which is in fact a
cast of the shell or outer covering of the organism.

Friable fossils, such as shells in unconsolidated beds,
are usually best preserved in the matrix. So far as they
are exposed to view, they should be slowly dried in the
sun or by the careful application of artificial heat, and
then, while still warm, immersed in a weak solution of
gum tragacanth, which gives a less glossy surface than
gum arabic. Bones of a similar friable character should
be dried in the same manner, and then dipped at once
for a few moments in a hot weak solution of gelatine or
glue, which should be nearly as fluid as water. They
should be treated in this way as soon as they are found,
and if possible before they are moved. A thin solution
of shellac in alcohol sometimes gives good results.
Fossil leaves in clay are apt to curl up and crumble if
dried. They may be preserved by the application of a
solution of gum tragacanth or gelatine.

Pyritised fossils are apt to oxidise and decompose
with the production of sulphide of iron and sulphuric
acid. They should be dried, and while still warm dipped
in molten paraffin wax. If decomposition has com-
menced the specimen should first be soaked for some
time in water to remove the sulphate of iron and sul-
phuric acid that have already formed.

Specimens of considerable size, such as vertebrate
skeletons, or large ammonites or groups of shells
embedded in a matrix only moderately hard, which are
liable to fall to pieces, require careful treatment. Bones
which do not require such careful treatment can be best
transported swathed in long strips of linen or calico,
which are afterwards hardened by the application of
flour paste, or the strips may be dipped in the paste
before they are wound round the bones.

Small fragile specimens may be held together by
dipping in melted paraffin wax. Too much stress cannot
be laid on the importance of packing specimens so
closely that there is no possibility of any movement in
the box in which they are placed for transportation.

day and Shate.—bpecimens ot clay may be placed in
paper bags or wrapped in paper and tuen packed in
uoxes. juarge samples may also oe laxen wiui tfie
Object of searching niem on. tfie first opportunity for
small lossils ana minerals, ror tins purpose tfie ciay is
aned and then crumbled up with tfie hand, and placed
m a linen or cotton clotfi, into wincn water is continu-
ously poured, while the clay is irom time to time turned
over, i'he clay gradually escapes through the inter-
stices of the ciotn, ana any small objects, such as
fossils, minerals, and rock fragments contained in the
clay will be left behind. These should be collected,
carefully dried, and folded up in soft paper, which should
be labelled and sealed with sealing-wax, and then packed
with similar samples in a small box. bhale, which is
hardened laminated clay, should first be converted into
a soft clay-like condition by repeated moistening and
drying. Where shale or clay contains plant remains,
there are often small seeds present which can be
separated by washing in the manner described, and
these furnish more trustworthy evidence of the nature
of the plants than the leaves and stems.

Sand and Gravel.—Specimens of sand may be packed
in the same manner as clay, but care is required to
prevent the contents of the packet from escaping.
Samples of gravels will rarely be required, but represen-
tative samples from the stones they contain, which will
afford valuable information as to the source of the
materials of which they are composed.

Oil, Water, and Gas.—If oil is found oozing from the
ground, a hole a foot or two deep should be dug at the
spot and allowed to till with oil, and from this as clean
a sample as possible should be taken, but it must be
remembered that crude oil is usually dark and malo-
dorous, very different from the refined material employed
for illuminating purposes. A gallon should, if possible,
be obtained to enable the oil to be properly examined.
It may be transported in bottles, which should be
washed out with oil from the same locality before they
are tilled. When each bottle is nearly full of oil a little
water may be added, and the bottle then securely
corked and sealed. If, as is usually the case, the oil
is lighter than water, the bottle should be carried with
the mouth vertically downwards. If the oil is heavier
than the water the mouth should be kept upwards. In
this way the water will prevent the escape of the volatile
constituents which form the most valuable portion of the
oil.

Samples of water may be taken either to ascertain
whether it is suitable for drinking or for use in steam
engines or commercial processes, or because it is believed
to contain salts or other constituents of medicinal or
economic importance. In either case a gallon is
required for a satisfactory analysis.

To collect a sample of gas which is escaping from the
ground a bottle should be completely filled with water,
corked, and inverted into the orifice from which the
gas is escaping. The cork should then be removed and
the greater part of the water allowed to run out. When
only a little remains the cork should be replaced while
the bottle still remains in the same inverted position.
It should then be securely sealed. If necessary, a
small cavity should be excavated in the rock to facilitate
the operation.

If the gas is escaping from water, a bottle is immersed
in the water which is allowed to fill it entirely. It is
then inverted and held with the mouth, still under
water, in such a position as to catch the gas as it rises.
When it is full of gas it must be corked before it is
removed from the water, and afterwards sealed.

A large amount of gas is desirable for analysis, but it