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THE COLLIERY GUARDIAN

November 3, 1916.

merits of highly productive shales have been found on
the surface, or discovered in trenching or draining oper-
ations, and these have excited local interest through
the power they possess of burning brilliantly when
thrown into the fire.

Selwyn, however, appears to have been the first to
observe that oil shale existed in Norfolk, and the result
of his examination is stated to have been the discovery
of a large body of rich bituminous shale.

It was not, however, until just previous to the
beginning of the war that any research work of a specific
nature was undertaken upon the Norfolk end of the
long Kimmeridge outcrop. The investigation revealed
.the presence of an oil shale series of very considerable
importance.

Stratigraphical Sequence of the Oil Shale Series.—In
section, the oil shale series, where exposed in the Puny
Drain, immediately east of the Ouse River at Setchey,
in Norfolk, consists of alluvium, recent sands, peat,
boulder clay, and boulder gravel, varied by pliocene
sands and the buried detritus of inter-cretaceous time
underlaid by black-blue clays belonging to the Upper
Kimmeridge beds, which are much trenched by pre-
glacial drainage channels, containing the remains of a
great erosion of the chalk and greensand.

This trenching has affected the upper series of blue
clay, but in no place has it apparently been responsible
for the absence of the oil shale series. These latter,
wherever they have been encountered, are found intact
beneath the pre-glacial water channels.

Lithologically, the clays are sharply divided from the
included oil shales. It is possible to distinguish two
types of oil shales occupying the upper horizons of the
Kimmeridge clays on the northern section of the Ouse
Valley outcrop. For convenience in classification, the
upper series has been called Smith’s, from the farm on
which it is found; and the lower has received the name
of Puny Drain series, from the Puny Drain, where the
outcrop was first discovered.

Productive Oil Shale Divisions. — The thickness of
Smith’s division may be anything from 100 to 300 ft.,
and undoubtedly comprehends several rich oil shale
seams. Two have already been discovered, one under
the limestone capping, and the second and larger seam
immediately overlying the sandstone stage, which is
believed to be more or less the divisional plane between
Smith’s series and the Puny Drain series. The seam
cut in the lower part of Smith’s series is not less than
6 ft. thick, and contains as much as 50 gals, of oil to
the ton.

The Puny Drain series includes one or more rich oil
shale seams, one of which has been exposed in the banks
and bed of the Puny Drain, south of King’s Lynn. This
seam is of a bluish-grey colour, open texture, and when
newly broken into is found to exude free oil, especially
when the broken out fragment is subjected to running
water. A similar instance of free oil being confined in
the shales is found when the limestone capping of
Smith’s series is broken through. Water covered with
oil immediately rushes into the workings.

The including clay beds are slate blue in colour, and
do not apparently show any trace -of oil. The thickness
of this seam is not less than 7ft., and on distillation
it yields from 50 to 51 gals, of oil per ton.

It is probable that the thickness of the Puny Drain
series is not less than 200 ft., and it may be as much as
500 ft. The bottom of the clays has not yet been deter-
mined. The aggregate thickness of the shale seams
already proved to the east of the outcrop, which are
capable of economical development, is 13 ft., but other
evidence is available, which renders it probable that
several other seams will be capable of exploitation.

Physical Characters of the Oil Shales.

The physical characters may be considered under
macroscopic, microscopic, and chemical composition.
Macroscopically, the shale appears to be of two kinds :
The upper series, or Smith’s shale, is a rather close-
grained rock, dark brown in colour, splitting along the
bedding planes into thin laminae, but with distinct planes
of fracture. The shale is highly elastic. When exposed
to air and sunlight, it rapidly loses moisture, and
becomes light in weight, but none the less durable.
Fragments of this class of shale are often met with on
the grass lands of the district.

The underlying, or Puny Drain, shale may stand as a
general type of all the shale series below it. It is a
greyish-blue rock, less apt to split along its bedding
planes into thin laminae, but prone to break into thick
and wide plates along fracture planes, and thus
resembles certain sandstones. No cross bedding has so
far been observed in it. The surface of the planes is
covered with a vast assemblage of calcareous fossils,
many of them impinging through the plane upon which
they have fallen, and resting upon lower planes. If
viewed edgeways, after fracture, across the bedding
planes, the rock is observed to be roughly vesicular or
open in texture, resembling somewhat certain types of
pumice.

Slides prepared from Puny Drain shale exhibit many
interesting characters. In vertical sections under a
high power, the field shows numerous straight lines,
representing the bedding planes., These are more
clearly indicated by strings or lines of carbonaceous
material, which, however, have the peculiarity of wedg-
ing out on approaching one another. Numerous rounded
spaces occupy portions of the field, resting upon the
bedding planes, but also appearing irrespective of them.
They resemble the mouths of loculi, filled with organic
material of a somewhat lighter colour than the car-
bonaceous matter of the wedges. That their contents
are organic, and not inorganic, material is proved by
their optical character.

With the exception of the above two classes of
material, practically the entire field of the specimens is
uniformly composed of a yellowish resinous-looking
substance, which may possibly be a form of kerogen.

When a higher power is used, it is seen that this
yellowish resinous-looking content is composed of two
distince substances. The darker of the two shows itself
as a darkish yellow substance, very uniformly distri-
buted throughout the field, comprehending the intervals
between the bedding planes, and stretching across these,
but without disturbing their lamination. The optical
outlines are indistinct, and towards the edges the whole
mass assumes a cloudy aspect. In places the colour is
much lighter, cloudy, and indistinct, but differs from
the second type of substance, to be presently described,
in optical qualities and apparent structure.

The second type of resinoid material occupies con-
siderable areas of the field, as laminae, more or less irre-
gularly spheroidal in shape. They are composed of
homogeneous translucent and waxy-looking material,
differing in its refractive index from the former, and
with clearly defined optical outlines. But what is
perhaps most distinctive is its possession of an internal
structure, represented by what look like cracks, occu-
pying its surface, and apparently extending throughout
the body of the laminae. These resemble cracks and
fissures in white wax when the material is subjected to
strain, and may result from similar conditions affecting
the laminae.

The relative quantity of the two substances in the
shale, as far as the specimens can determine, seems to
be in favour of the former. The laminae are seen to
occupy considerable areas of the field, but do not dis-
turb the bedding planes. Both substances in a general
wray, but especially the latter, remind one of gelatinised
scum, more perhaps than anything else.

Inorganic grains are present in all the specimens,
mostly in the form of silicates of alumina, with iron,
potash, and water, such as glauconite, several grains of
this light green mineral being met with in the field, but
not nearly so frequently as in the Kimmeridge of
Dorset. Quite a considerable number of grains of mica
are met with, besides many carbonates, probably of
lime and iron. There are no sand courses visible in
the specimen, such as are so frequently met with in
ordinary shale.

The specific gravity of the Norfolk shale varies with
the various fragments, doubtless owing to air inclu-
sions. Four different fragments gave 1'397, 1-324,
1'403, and 1-260. When the material was crushed to
30-mesh, its specific gravity was 1-55. Its specific
gravity, therefore, more nearly resembles the heavier
class of torbanite or kerosene shale, which is 1-30. It
is heavier than cannel coal, which is 1'26, or asphaltum,
which is 1-2. It approaches near to Californian fullers’
earth, which is 1’85 to 2'0.

Chemical Composition.

It is found when the shale is shaken up with ether
that it is possible to recover as much as 1 per cent, of
oil, whereas when shaken up with carbon disulphide the
shale yields only 0'25 per cent.

A number of analyses have been made of the Norfolk
oil shale, showing that the average volatile content in
the two' series is remarkably constant. Three analyses
may be given as examples of the relative value of the
two series :—

Smith’s Series.

Moisture	.............

Volatile organic matter..
Fixed carbon .........
Ash ...................

Puny Drain Series.

9-8	...	8-0	...	4-1

35-1	...	31-7	...	37-1*

15-3	...	16-3	...	12-0

39-8	...	44-0	...	46-8

* Including combined water and organic sulphur.

Analysis of the inorganic contents gave the following
results :—

Moisture of water volatilised at 100 degs. Cent. ... 4-100
Calcium carbonate ............................ 8-800

Calcium triphosphate, Ca3P2O8 (equivalent to

P2O. 0-4 per cent.) ........................ 0-892
Iron pyrites (containing Fe 1-22, sulphur 1-46)... 2-680
Alumina, soluble in hydrochloric acid ........... 4-860
Ferric oxide ................................... 1-510

*	Silica ......................................... 22-680
^Alumina ...................................... 4-620
^Ferrous oxide ................................. 1-380 *

.................................

*Limje and magnesia ........................... traces

*	Sulphur unoxidised, probably in organic com-

binations ................................... 2-860

Total organic matter and combined water (by
difference) ................................. 45-618

_______

100-000

* Insoluble in hydrochloric acid.

After roasting to oxidise fixed carbon, the analysis of
the inorganic matter gave :—

Percent.

Silica .......................... 49-58

Alumina ........................ 20-20

Ferric-oxide .................... 10-27

Lime .............................. 11-68...........................

Magnesia and carbonic acid ......	1-22

Sulphuric acid ..................	6-30

Phosphoric acid .................	0-83

100-00

After distillation of the volatile hydrocarbons, analysis
of the coke gave residual sulphur 2-81 per cent. This
tends to show that some of the organic sulphur is fixed
by the earthy bases during distillation, as it is in excess
of that which is due to the ferrous sulphide (FeS) which
would result from heating of the pyrites content under
the conditions of the distillation. Thus the sulphur
that was eliminated with the volatile matter was about
0-6, whilst that remaining fixed in the coke residue was
0'4, of the 4-32. The inorganic contents of Norfolk
shale after roasting intimately resemble spent Scotch
shales, especially in the silica, alumina, and ferric-oxide
contents.

Analysis of Organic Contents.—The organic contents
of the shale common to the Puny Drain are remarkably
constant in amount throughout the series, both along

the outcrop and on the dip. The oil in the Puny Drain
shales appears to be derived from two different sources.
First, from indigenous material, possibly of animal
origin, for the vast numbers of marine fossils of which
the shales are so largely composed, especially the large
degenerate perisphinctoid type of ammonites, would be
sufficient to allow of such an origin for a part of the
oil being within the range of possibility. And secondly,
the oil must have been derived from a source of free oil.
Whether this is formed in situ, as the result of the
natural distillation of more deeply seated shale beds and
the rise of the resulting volatile products into the super-
ficial and superincumbent beds, -which are now exposed,
or whether, as seems more probable, it comes from a
source of liquid fuel oil confined at a high pressure
beneath the series, it is not yet possible to demonstrate.
That free oil does exist is clearly shown by three classes
of evidence. First, that as much as 1 per cent, of oil
is dissolved when the shale is treated with ether;
secondly, from the prospecting side, when the limestone
capping is penetrated, and water covered with oil
appears in the sinking, or when a piece of shale recently
broken out from the bed is subjected to running water,
and the oil is seen to escape and form a scum on the
surface; and thirdly, when the shale is treated in retorts,
when it is found that the greater part of its oil contents
comes off at a temperature under 300 degs. Cent.

Physical Character of the Oil.—The oil obtained from
both series of shales is golden-black is colour, with a
purplish tint on reflected lights. The oil is very fluid,
running almost like water, despite the fact that its
specific gravity is as high as 0'942 to 0*960. In this
respect, it differs from the Scotch shale oil, which is
dark green in colour, with a specific gravity of 0-860 to
0-890, and is very viscous, with a settling point of about
32 degs. Cent. Norfolk shale oil differs likewise from
oil derived from the Dorset-Kimmeridge series, both in
its colour and in its viscosity. The specific gravity of the
motor spirit or petrol obtained from re-distillation of the
oil is 0-855, with a low flash point. Scotch shale
naphtha has a specific gravity of 0-734.

Bulk tests carried out on Puny Drain shales gave
highly satisfactory results. The yield of oil on a com-
mercial basis was 40 gals, to the ton, the nitrogen
content was about 1 per cent., and the yield of sulphate
of ammonia was 66 lb. per ton; while there was obtained
25,000 cu. ft. per ton of dry gas possessing highly illu-
minating properties. Sulphur contents were as high as
6'4 per cent. The oil obtained on these bulk tests had a
high specific gravity, namely, 0-942 to 0-960, was very
fluid, and yielded on distillation :—

Fractionation up to 100	degs. Cent...........	3-8	...	3-8

,,	,,	100	to	170 degs.	Cent....	5-7	...	9-5

,,	„	170	to	245 degs.	Cent....	19-2	...	28-7

„	,,	245	to	310 degs.	Cent....	39-2	...	67-7

Water ........................................ 0-8 ... 68-5
Pitch and loss ............................... 31-5 ...100-0

In the field trials, fractionation of the oil gave results
as follow :—

0 to 185 degs. Cent..................... 23-3
185 to 250 degs. Cent..................... 24-6
250 to 300 degs. Cent..................... 20-8
Above 300 degs. Cent, by difference .... 31'3

The yield of fractions coming within the limits of the
motor spirit series is considerable, and of the utmost
importance. In addition, the oil yields from 3 to 4 per
cent, of bases extracted by weak acids, 3 to 4 per cent,
of crude phenols, cresols, etc., and 3 to 4 per cent,
benzol and toluol.

The main interests of these bulk trials is the extremely
low temperature at which the shales yield a big propor-
tion of their oil contents, and that the residues contain
20 to 27 per cent, of carbon, fixed and unfixed.

Sulphur Contents.—It is impossible, with the above
data available for analysis, to be any longer sceptical as
to the value of the shale that will produce an oil in such
quantities, and of such quality, containing so many
by-products. Only one factor may be conceived to affect
the value of the deposits, and that is the quantity of the
sulphur contents, which vary from 4'32 to 7'8 per cent.
Here the shale conforms to the known sulphur contents
of the Kimmeridge series generally. An interesting light
is thrown on to the question as to the form in which the
sulphur is contained in the shale, by the analysis of the e
inorganic and organic constituents. There it is shown
to be in two forms, organic and inorganic, and that part
of the organic derivative seems only to be held by the
inorganic bases during distillation. Although the elimi-
nation of the sulphur from the Kimmeridge shales has
been found a difficulty, it need not be inferred that it is
insurmountable. There are already indications that
methods are in being to effect this object. The sulphur
contents of the Norfolk shales do not seem to be obsti-
nately “ held,” and already it has been possible in the
laboratory to effect the elimination of the sulphur con-
tents to below the figure (namely, 3 per cent.) sanctioned
by the Admiralty. It is a step in the right direction,
and there does not appear to be any reason why similar
success should not be obtained in commercial practice,
or, indeed, that practically the entire sulphur contents
should not be eliminated. Still, in view of the fact that
there are oil shales which are found difficult to treat for
the sulphur incorporated therein, it seems from a prac-
tical point of view that a great deal has been made of
the sulphur difficulty. Evidence is to hand that shale
oil containing as much as 4 per cent, of sulphur has been
used in internal combustion engines without any trouble
resulting; and in steam boilers it is, of course, very
much less. For steam raising, coal with over 2 per
cent, sulphur is regularly employed. Even Welsh coal
has an average of 1'43 per cent. Weight for weight,
much less oil than coal is required; therefore, relatively,
less sulphur is liberated in the firebox. One ton of fuel
oil containing 4 per cent, of sulphur will liberate in a
boiler furnace 90 lb. of sulphur. The equivalent of coal