1122

THE COLLIERY GUARDIAN.

June 15, 1917.

mometer immersed in the liquid about f in. from the
bottom (see later).

The following tests are conducted in distillation
flasks with side outlet, the bulb of the thermometer
being in the path of the vapour, just below the side
tube, and are in accordance with requirements under
the present war conditions: —

Standaid benzol... At least 95% at 90° C.

Toluol............ 90%	between 100° and 117° C.

Solvent naphtha... 90% between 130° and 160° C.

The first stage in the treatment of the crude benzol
consists of a preliminary distillation, the main object
being to separate the bulk of the wash oil and naphtha-
lene. The whole of the more volatile products may be
“ blown over ” in a preliminary still into one collect-
ing tank, and the blown-over product—consisting of a
mixture of benzol, toluol, and solvent naphtha—is
afterwards treated with sulphuric acid and caustic
soda in a special washer. The washed product may
then be fractionated into the respective washed pro-
ducts, benzol, toluol, etc. The more common practice
is to effect a certain degree of fractionation in the
blowing-over stage, splitting up the crude benzol into
unwashed 90 per cent, 'benzol, toluol, and solvent
naphtha fractions, etc. These products are then
separately washed, and since the proportions of wash-
ing media vary considerably for each of these frac-
tions, more efficient and economical washing is
obtained. The washed products are then re-distilled
with a more or less severe fractionation, according to
the specification aimed at.

Rectification Piant.

The general scheme of a benzol rectification plant is
shown in fig. 2. The still A is charged with crude
benzol from the tanks 1 and 2, and is gradually heated
by dry steam, at C, passing through a series of tubes
adapted for easy removal in case of repairs, etc., the
pressure being maintained by a steam trap. The first
vapours expelled from the crude benzol contain a high
proportion of carbon disulphide, and rise through the
fractionating column E, and the dephlegmating sec-
tion F. The latter section consists of a multitubular
cooler, in which water passes round the outside of a
series of tubes, whilst the benzol vapours, etc., rise
upwards through the latter. By regulating the flow
of the cooling water, a partial condensation of the
vapours is brought about, only the most volatile com-
pounds being allowed to pass. The vapours passing
the section F are completely condensed in a condenser
G, and pass through a visible overflow arrangement to
a store tank 3, 4, or 5. In most cases, the “ first
runnings ” are isolated to reduce the proportion of
carbon disulphide in the ‘‘blown over” benzol. The
products of higher boiling point, selectively condensed
in F, pass back into the column E, and in their descent
scrub out of the ascending mixture of vapours a con-
siderable proportion of the particles of higher boiling
liquids carried forward mechanically. In due course
the first runnings are expelled, and the temperature of
the still is allowed to rise, the products now coming
away containing a large proportion of benzene, and
giving, on condensation, an unwashed product in tank
3, suitable for working up into washed 90 per cent,
benzol. "When a distillation test of the condensate
from G gives the necessary indication, the temperature
of the still is allowed to rise still further, the quan-
tity of water flowing through F being at the same time
checked so as to allow the temperature to rise, thus
permitting the passage of higher boiling products.
These, on condensation, give a liquid in which toluene
predominates,, and which is then diverted to the tank 4
for subsequent working up into washed 90 per cent,
toluol. Similarly, a naphtha fraction is next driven
off, but in this case the temperature of the enclosed
steam is not high enough, and open steam is admitted,
the mechanical action assisting in the expulsion of the
naphthas. Occasionally the still is worked under a
vacuum. Simultaneously, the water is cut off entirely
from F, and the condensed product passes to 5, to be
worked up later to solvent and heavy naphtha. After
a little experience with any particular make of crude
benzol, a good indication of the change-over points for
these respective products may be obtained by allowing
a certain volume of each product to come over before
changing on to the next fraction. The residue left in
the still consists mainly of naphthalene and wash oil,
and is run to a cooling tank N, in which, after cooling,
naphthalene is deposited and is removed by filtration,
the clear oil passing to the wash oil store tanks. The
crude products in 3, 4, or 5 are individually pumped to
the washer H by means of the pump P. The washer
consists of a lead-lined cylinder fitted with an agitat-
ing device. Here the product is washed by sulphuric
acid, w’ater, caustic soda, etc. Pyridine bases combine
with the sulphuric acid, whilst phenolic bodies, olefines,
and unsaturated hydrocarbons form with the acid thick
resinous substances which sink to the bottom. A por-
tion of the thiophene is also removed. The duration of
the agitation period, amount of acid and soda used,
number of washings, etc., vary considerably with the
quality of the crude products, scarcely two plants
working under similar conditions. The following may,
however, be given as an approximate guide: —

(1)	Wash one hour with 4 per cent, by weight of
sulphuric acid, 168 degs. T.

(2)	Rest one hour, and run off acid.

(3)	Wash one hour with 3 per cent, sulphuric acid as
above.

(4)	Rest one hour, and run off acid very carefully.

(5)	Gently wash the sides of the washer with water
without agitation, and run off.

(6)	Wash with water 20 minutes with gentle agitation,
and run off after one hour rest.

(7)	Wash with 1 per cent, caustic soda, 40 degs. T.,
half an hour.

(8)	Rest one hour, run off.

(9)	Wash with water as before.

The washer is fitted with a conical shaped bottom to
allow the acid, etc., to be separated to the last drop.
The thick spent acid is collected in a tank I, in which
it is agitated by live steam. This brings about a

separation of the hydrocarbons, partly by evaporation,
and partly by coagulation into a scum, which may be
removed in J by filtration, the clear dilute acid being
then suitable for use in the sulphate house. The
washed products are conducted to the final rectifying
still B, the treatment there being on lines similar to
those obtaining in the primary still A.

(To be continued.)

MI.OTC; INSTITUTE OF SCOTLMB.

A meeting of the Mining Institute of Scotland was
held on Saturday in the Heriot-Watt College, Edin-
burgh. Mr. D. M. Mowat, Coatbridge, the president,
occupied the chair, and there was a representative
attendance of members. Mr. James Cumberford,
colliery manager, Coronel, Chili, and Mr. William
Smith, agent, Wear Colliery, Kingseat, Dunfermline,
were admitted to membership. The following gentlemen
were elected to represent the institute on the council of
the Institution of Mining Engineers for the year
1917-18:—Messrs. D. M. Mowat, Coatbridge; Wallace
Thorneycroft, Bannockburn; J. T. Forgie, Bothwell;
James M. Strain, Glasgow; R. W. Dron, Glasgow;
Wm. Williamson, Hamilton; J. Balfour Sneddon, Mid-
Calder; C. A. Carlow, Leven; Jas. Barrowman,
Hamilton; James Hamilton, Glasgow; Wm. Smith,
Dalmellington; Sam. Mavor, Glasgow; Robert M’Laren,
Airdrie; and Douglas Jackson, Coltness Iron Works,
New Mains.

The Form and Stricture of the Coal Fields of Scotland.

Discussion was resumed on the paper contributed by
Mr. David Ferguson, Glasgow, on “ The Form and
Structure of the Coal Fields of Scotland.”*

Mr. J. B. Thomson (Hamilton) said there were one
or two points in the paper he would like to refer to, the
first being the author’s difficulty in reconciling the
“ growth in situ ” origin of coal with the non-uniformity
in the character of the coal, so that he had had recourse
to the drift theory or sedimentary formation. He would
like to ask Mr. Ferguson if he had ever seriously con-
sidered any other theory than the one of vegetation in
regard to the origin of coal. He (Mr. Thomson)
remembered reading, very many years ago, of a theory
that was advanced by an American professor of geology,
Veghen, he believed, was the name—namely, that of sedi-
mentary formation. To the lay mind—to one who had
not studied geology very minutely—Veghen’s arguments
against the vegetation theory were very strong. Although
Veghen’s theory might not stand the criticism of Air.
Ferguson’s geologically-trained mind in every detail, it
might be worth while for the author to consider
it, as it certainly supported his own theory that
coal seams were thickest and best in the basins and
thinner at the fringes or shore lines. Coming now to
the second point on which he desired to speak, he
thought they were all agreed as to the urgent necessity
of ascertaining the condition of the coal and ironstone
seams in the carboniferous limestone underlying the
upper coal measures in the Clyde Valley basin. Even
if it were possible to start boring operations within the
next 12 months, and if these were to prove that valuable
coal seams existed, it would take 20 years to sink pits,
open them up and develop them sufficiently to give an
output equal to the present output of Lanarkshire, and
prol?ably very few existing collieries would still be
working then: The author suggested that the deep
boring operations in the centre of the basin between
Carmyle and Uddingston would be of economic value.
Personally, he (Mr. Thomson) would suggest more
extensive operations along a line running from Carmyle,
vid Uddingston, Motherwell, Wishaw to Salsburgh, and
he was of opinion that if a sum of £50,000 were raised
for this purpose, sufficient bores could be put down to
prove the full economic value of the limestone measures.
Now, where was this sum or a larger one, if necessary,
to be obtained ? Mr. R. W. Dron had suggested that
the State should step in, and thought it would be easy
for the Government to take possession of the deep
seams and prove them. His (the speaker’s) fear was
that it would not be easy to convince the Government
of the absolute necessity of going on with the boring
operations immediately. So long as they thought they
could get abundance of coal from South Wales,
Yorkshire, Kent, etc., they would not likely concern
themselves much about a hidden coalfield. The
question came to be who were the persons most
concerned in maintaining the coal output in the Clyde
basin ? First, there were the landlords and owners of
the coal and, second, there were the people who.
depended for their livelihood on the production of coal
and allied industries. These people were represented
by the local authorities of the burghs of Wishaw,
Motherwell, Hamilton, Airdrie and Coatbridge, the
County Council of Lanark and the city of Glasgow.
Thirdly, there were the coal masters or owners of
existing collieries in the area who might be expected
to sink, or who might expect to sink pits of their own
or amalgamate with each other to secure larger blocks.
Then there were the iron and steel manufacturers, the
proprietors of bridge works, and other large consumers
of fuel, whose interest, of course, it was to have a cheap
supply of coal; and, finally, there were the members—or
at least a percentage of the members—of the Mining
Institute of Scotland, whose interest lay in the fact that
when there was no more coal to work they would have
to look for pastures new. It might be contended that
this being an economic subject it was not suitable for
discussion in the institute, but he would direct their
attention to the objects of the institution as stated in
the by-laws—viz., “ The advancement of coal and iron
ore mining and allied industries, and the promotion of
the acquisition of the knowledge necessary for the
control and direction of mining operations in relation
to stratified deposits.” He would suggest that the
members of the institute should instruct the council to
formulate a scheme whereby the necessary funds could
be raised. If this were done, and it were the means of
bringing the matter prominently before the parties

* Colliery Guardian, September 22, 1916, p. 545.

concerned, and securing from them the requisite
■financial assistance, he would consider that the members
of the institute had contributed their quota. In addition
to this, however, they could produce in one of their
oldest members a man gifted and qualified to act as
consultant to any board that might be formed for the
purpose. He referred to the author of the paper, Mr.
Ferguson.

Mr. James Hamilton (Glasgow) said that while
they were all interested in the scientific speculation as
to the prospects of finding workable coal in the
carboniferous measures in the Clyde Valley section of
the coal field, one could not help feeling sceptical,
particularly in view of what was known of these
measures to the south-west of the Eddlewood fault.
For that reason, boring in the district however carried
out would be welcomed alike by the purely scientific
and by the commercial mind. The suggestion put
forward by Mr. Dron for the expenditure of Govern-
ment funds in proving the strata there, could scarcely
be looked for in these times, although if it could be
arranged it would certainly expedite the work. He was
satisfied that such work would be just as well done on
commercial lines, because, after all, the expenditure was
not beyond the resources of indust rial concerns, and
the leasing of a sufficient area need not be difficult.
Whoever took the risk would expect and be entitled to
reap the benefit. If the existence of workable coal was
proved beforehand, a lessee must expect less favourable
terms. Unproved, the risk was greater, but so also was
the prize if the venture proved successful. The old
controversy as to the origin of coal inevitably emerged
in a paper of this description, and lie did not know that
anything more could be usefully said on that point.
Speaking for himself, he found the difficulties were about
as great on the one side as the other. Mr. Ferguson
contrasted the difficulty of explaining variation of
thickness of the deposits if they grew in situ, with the
naturalness of each variation if drifted from the
surrounding land areas and deposited in water. But
was there any greater difficulty of explaining varying
thickness by local variation of conditions more favour-
able and less favourable than there was in explaining
the small quantity of ash in a coal seam in view of the
necessary transportation and deposition of impurities
carried by streams in one place, and the coal-forming
material in another ? As to the variation in thickness,
in growth m situ, it could be seen any day in the
varying depth of peat over a stretch of moss. He might
instance the case of the Main and Pyotshow seams,
where within less than 100 yds. or so the separating rock
was found to vary in thickness from a few inches to
18 or 20 ft, mostly sandstone, and yet the coal did not
vary materially in character. The real truth was that
our imagination was not capable of visualising the
conditions necessary to account for the phenomena,
unless something approximating to the process could be
seen going on day by day. After all, the question of
the origin of coal was one of academic interest only.

Air. John Masterton, H.M. inspector of mines
(Edinburgh), said that the author, in the course of his
most informative paper, had dealt with the coal fields
in the Firth of Forth, the Lothians and in Fife. In the
east of Scotland they were much interested in that
subject. It seemed to him that Air. Ferguson took a
much more sanguine view of the Firth of Forth coal
field than most geologists did. He appeared to have
the hope that that coal field went round to Dunbar,
but the speaker did not think he would get many
geologists to agree with him on that point. Personally
he thought there was little hope of the eastern end of the
coal field tailing away round to Dunbar. Certainly,
from the information and data the author had placed
before them, there appeared to be a prospect of develop-
ment with a reasonable possibility of success in the
Firth of Clyde Valley. While they were arranging to
bore for the bottom seams in Lanarkshire he thought
they ought also to be setting their minds together to
devise the best means of getting the coal out from
underneath the Forth. The present methods of going
about the work seemed to be absolutely hopeless. As
it was, they were two miles out just now at the furthest
point, but it was quite evident that the difficulties were
going to be haulage and ventilation, and chiefly the
former. How were they going to get along when they
got, say, five or seven miles out ? He thought they
should embark on some scheme of tunnelling under-
neath the Forth, and it appeared to him that there was
nothing to hinder a 7-ton ordinary railway wagon being
run in through that tunnel. At the side of the tunnel
there was nothing to prevent the erection of a single
screening unit, so that they could screen the coal,
separate the round from the small and place into
wagons. So far as they had gone in their operations
under the Forth, the conditions as to gas and dust were
such that the tunnelling scheme could be undertaken
with absolute safety.

Air. R. W Dron (Glasgow) thought that the
suggestions which had come from Messrs. Thomson and
Masterton in the course of the discussion were most
refreshing. He would go a step further than Air.
Alasterton and say—why not run this tunnel right
through and make it a railway from Edinburgh to Fife,
going in for passenger traffic and everything else they
could? The screening plant could be conveniently
situated at the sides of the railway. During recent
years very considerable investigations had been made as
to radial activity, and he would like to know if the
author had considered the point as to how far greater
radial activity during the carboniferous period might
have accounted for the abnormal growth of plant life
during that period compared with what they saw just
now.

The President said he agreed with the point raised
by Mr. J. B. Thomson in regard to deep boring in the
Clyde Valley district. As to how that might be done,
however, there would doubtless be many conflicting
opinions. If it were to be carried out by public money,
then the Government was the proper source to apply to
for that. Coal was a national asset, and as the entire
district of the West of Scotland depended on the mining
industry, it would be for the Government to consider