September 27, 1918.

THE COLLIERY GUARDIAN.

655

cular weight and physical density of the heavier
products of carbonisation, while increasing the yield of
gas and of the lighter constituents in the tar. This
accords with experience, and when in action tends to
emphasise the difference which already exists between
the products of the vertical and horizontal retort in
virtue of the lessened extent to which the primary
volatile products of carbonisation in the former are
subjected to the influence of red-hot coke and radiant
heat.

In so far, then, as secondary products of carbonisation
are required—and we must remember that this class
includes benzene and toluene and other valuable
materials for the making of dyes and drugs—the
processes and plants which excel in the rapid extrac-
tion and removal of products without extensive decom-
position may have their drawbacks. The light oil and
other tar constituents tend to retain the parafiinoid com-
position which seems to be characteristic of the chemical
groups first detached from coal when it is subjected to
heat. At the same time we must bear in mind that the
yields of light oil (motor spirit) and fuel oil
—two commodities with enormous possibilities in
an ever-expanding market—are increased, and that
the same applies to the gas itself. Moreover,
it is evident that there is no inherent impos-
sibility in so modifying the design of our carbonising
appliances—of the retort and its setting—that the car-
bonisation itself may be carried out at the temperatures
and under the conditions which are best for the process,
and that the volatile products of carbonisation leaving
that part of the retort may be deliberately subjected to
another temperature or other conditions which will
bring about desired changes in their character. This is
a question of design, and should offer no insuperable
difficulty to the constructional gas engineer of to-day, and
still less, Prof. Cobb hoped, to the scientifically trained
gas engineer of the near future.

Instead of sending water gas through the retort,
steam might be blown in, and something could be said
for either way of working. Heat had to be supplied in
either case for the decomposition of the steam by
carbon, and it was undoubtedly cheaper to supply this
heat on the w'ater-gas plant by the combustion of a
portion of the carbon in air than it was to convey the
necessary heat through the walls of a retort. Moreover,
unless the temperature inside the retort was high, the
water gas reaction occurring there was liable to produce
an inconvenient amount of carbon dioxide. On the other
hand, steaming of the retort had another function, which
it performed, in his opinion, very much more satisfac-
torily than could be expected from water gas—the
production of ammonia, which was, he believed, likely
to play an important part in the development of
economical carbonisation in the near future.

Referring to published results obtained from steaming
vertical retorts, Prof. Cobb submitted results of tests,
compiled by Mr. Frank Clark, from which the improve-
ment in gasification was manifest, and it is seen to
have been accompanied in every case by an increased
production of ammonia. Mr. Lawrence Hislop’s useful
and continuous work at Uddingston was completely
confirmatory and pointed just as clearly to the possi-
bilities of this method of operation.

Yield of Ammonia.

What had been done so far was not to be taken as
the limit of what was possible. As regards ammonia
recovery, too much stress had, in his opinion, been laid
upon the reaction associated with the name of Tervet.
Frequent reference was made to Tervet’s results as
justifying the assumption that the passing of hydrogen
through coke liberated quite large quantities of
ammonia. Tervet gave from 29*65 to 57*02 lb. of sulphate
obtained from the same coal in the laboratory by him in
successive experiments, the temperature and flow of
hydrogen being increased gradually. It was noticeable,
however, that Tervet limited his claim to the effect of
hydrogen at a certain stage of carbonisation when the
free evolution of gas ceased, and in one passage of some
significance he stated that a coke incapable of yielding
nitrogen on prolonged ignition evolved no ammonia in
a current of hydrogen. These limitations left the sub-
ject in a state of undesirable obscurity. The quantity
of nitrogen left in ordinary gas coke was about 50 per
cent, of that present in -the original coal, and, both
financially and technically, it was plain that great
importance should attach to any reasonable possibility
of obtaining this coke nitrogen as ammonia.

Supposing the influence of atmosphere to be impor-
tant, it became advisable to know how the coke behaves
with different gases. Some years ago Mr. C. A. King
made some experiments for Prof. Cobb on this subject
in the laboratory of the Farnley Iron Company.
Coke and coals were subjected to the action of a number
of gases at a temperature of 800 degs. Cent , the
ammonia formed being absorbed in acid and determined.
The temperature of 800 degs. Cent., was chosen as
promising the best results after preliminary experi-
ments. From the results it appeared that dry
hydrogen did not liberate any large quantity of nitrogen
from soft coke as ammonia, and that the only gas which
did so was steam, either alone or accompanied by hydro-
gen or nitrogen. The Tervet reaction might, therefore,
have its place, but steam was the great ammonia .pro-
ducer, if it could only be utilised effectively.

It might very well be argued that the full yield of
ammonia could only be obtained by a gasification of
the carbon, which gradually opened up the way for the
attack of steam on every molecule of the contained
nitrogen compound, and the consequent production of
ammonia. The idea of such complete gasification by
steam in retorting practice was at first sight fascinating;
. it was, indeed, a form of the continuous water gas pro-
cess which had attracted many minds. The difficulties
of its complete realisation were, however, very great.
It would hardly be possible to make a working success of
any of our retorting plan's, or of any plants resembling
them, if it were necessary to transmit through the
walls of the retort, not the comparatively small quantity
of heat required for carbonising but the comparatively
enormous amount necessary to gasify completely
the carbon by the water-gas reaction, which absorbs 4,320

B.Th.U. for every pound of carbon converted into
carbon monoxide. Even if it were practicable to supply
sufficient heat, a choice would have to be made between
working at a temperature low enough to conserve the
ammonia, which would result in the production of an
inconveniently large quantity of carbon dioxide, or
working at a temperature higrh enough to keep the
carbon dioxide within reasonable limits, with consequent
destruction o 1 ammonia.

There remained, however, the question whether
anything like complete gasification of the coke was
necessary to allow a contact between steam and the
nitrogen compounds in the coke sufficiently effective
to improve materially the ammonia yield. The results
that were obtained show that without the gasifica-
tion of more than a very small percentage of the coke it
is possible, by treatment with steam and hydrogen, to
liberate a considerably larger proportion of the ammonia
than is recovered in any ordinary carbonisation process.

Reference was next made to limiting considerations,
important in large scale operations. In the laboratory
experiments it is noticeable that only steam was able to
give any large ammonia yield from coke, and that
other gases had little or no tendency in that direction.
No doubt, nitrogen and hydrogen would tend to
preserve any ammonia formed, and, no doubt, even a
gaseous current of no chemical import would be of
service in washing the newly formed ammonia from the
pores of the coke, and sweeping it away before it could
decompose. This was of itself useful, because, in the
ordinary atmosphere of carbonisation at 800 degs. Cent.,
any ammonia formed would be almost completely
decomposed if it were not so swept away into cooler
regions. But, substantially, steam was the ammonia
producing agent, and since it could never dominate in
quantity in the same way in the gas retort as in the
laboratory experiments, it would be unwise to prophesy
how nearly results obtained under laboratory experi-
ments could be approached on the working scale.

Attention was also directed to the very low result ob-
tained even with the moist hydrogen from hard beehive
coke. It is evident that when coke is sufficiently hard, it
is very resistant to the chemical attack of any gas, and
this is, no doubt, the reason for Tervet’s negative results
with hydrogen and long-ignited coke, and alco the
reason, incidentally, why gasification of such material
as coke-oven breeze and dust in gas producers by the
Mond process is unsatisfactory, both in rate of gasifica-
tion and in ammonia yield. Hence the necessity for
large scale trials. It might be said, with some truth,
that such trials had already been m*de; but they had
been made with existing appliances, which were naturally
unsuitable in detail for the purpose.

The possibilities were of such importance to the gas
industry that a very thorough trial was justified under
Conditions which would allow of passing into the retort
measured quantities of steam, either alone or mixed with
other gases. Moreover, in order to minimise the cooling
effect on the charge, it should be made possible to
superheat the steam to any desired extent, and to intro-
duce it at any point. If the ammonia yield could be
appreciably increased, it was evident that the cost of
the necessary structural alterations would be of trifling
consequence.

Theoretical Considerations.

The decomposition of benzene on heating might be
regarded as one of the simplest forms which the process
of carbonisation could take. With both benzene and
toluene, certainty of statement only attached to the
earlier stages*of decomposition which had been actually
sworked out. The later stages were under examination,
and their description was hypothetical. Tbe two
gases—hydrogen and methane—were dominating con-
stituents of coal gas, and their formation in the
carbonisation of coal, might be regarded as taking
place in a similar way—the hydrogen from molecular
condensation, and the methane from interaction of H
and CH3 groups.

In the accompanying table the carbonisation of coal
is represented from this standpoint. It is evidently not
a complete scheme of carbonisation, since, for the
present, oxygen in the nucleus is not included in it, but
it brings out the dominant part played by hydrogen
throughout the process.

CH3 groups.

Carbon hydrogen nucleus.	Other groups

more loosely
attached.

Yieldsup to600 degs. Cent.: —
Nucleus CH3 condensed with
elimination of H2.

Yields up to 800 degs. Cent.

Nucleus further condensed
with elimination of more H2.

Yields up t > 1,000 degs. Cent,
and higher temperatures.

Nucleus condensing ulti-
mately to carbon.

groups detached
+ (with addition of H2)
liquid and gaseous.

+ CH4

(by addition of H).

+	H2.

The detached groups undergo secondary decompositions.

The nucleus in this case was not a single substance,
for. as pointed out in the valuable monograph on the
“ Constitution of Coal ” published recently by Dr. Marie
Stopes and Dr. R. V. Wheeler, coal probably consists
of a number of different degradation products of the
original coal substance, and each of these may decom-
pose on carbonisation in a somewhat different manner.
The process in general would, however, be of the
character indicated. Vignon, who examined the gaseous
products of carbonisation collected through different
temperature intervals, felt justified in dividing the
carbonisation process into three stages. In the first
stage came off unsaturated hydrocarbons, higher
paraffins, phenols, oils, etc. In the second stage
methane was the principal product, and in the third
stage hydrogen.

The work of Dr. Wheeler and his collaborators was in
substantial agreement with that of Vignon in this
respect, and the results of a thermal study of the
carbonisation process by Mr. Rollings and the lecturer
was consistent with it. The method of representing the
results of carbonisation which he had adopted in
the above table as a development from the study of the
decomposition of benzene and toluene, marked the same

succession of phenomena. The loosely attached groups
which were shown as breaking away with the addition
of hydrogen up to 600 degs. Cent., were paraffins, unsatu-
rated hydrocarbons, phenols, and constituents of paraf-
finoid tars, such as were produced by low-temperature
carbonisation. In the ordinary process these were exposed
to higher temperatures before escaping from the retort,
and yielded the many aromatic ring compounds which
constitute medium temperature tar. Higher benzene
ring compounds existing, as they do, in the presence of
hydrogen tended to be reduced to benzene, naphthalene
and anthracene—compounds which consist of rings
without attached groups. This tendency was more
marked when carbonisation was conducted at high
temperatures—particularly with free exposure to red-hot
coke and radiant heat. Such rings ultimately decom-
pose, with the formation of carbon, but with difficulty.
The molecular configuration of the ultimate product,
carbon, was difficult to determine. But, as had been
pointed out by Rhead and Wheeler, both graphite and
amorphous carbon had on oxidation yielded a compound
with the characteristic benzene nucleus in its constitu-
tion, while Aschan had suggested a formula for carbon
which involved again the persistence of benzene nuclei
in aggregation. All signs pointed to the stability of
this six-atomed ring under the most drastic treatment,
including the great thermal and chemical strains of
carbonisation.

THE LONDON COAL TRADE.

London, September 26.

The demand for coal of all kinds in the London market
is as strong as ever. There has been a slight increase in
the tonnage arriving in the metropolitan area during the
past week, but the quantity is totally inadequate to the
requirements at the present time. Merchants are con-
stantly pressing for coal on order, and although the
delivery trade is brisk there are still considerable arrears
in the orders in hand, and very little can be put into
stock. Steam coals are exceedingly short, and the col-
lieries report a very heavy pressure for coal on order.
The seaborne market has suffered somewhat from the
rough weather along the coast, but the arrivals in the
Thames have been fairly satisfactory. The vessels are
principally bringing gas coal to London. Twenty-two
ships arrived for Monday’s market and 14 for Wednesday.
The ships arrive in groups. The position of the slack
market is not quite so firm as in previous weeks, owing
to the smaller deliveries made in the cotton spinning
districts, thus allowing a larger quantity of slack to come
forward into the London area. During the week an
important meeting has been held at the Mansion House,
presided over by the Lord Mayor of London. A large
number of the metropolitan and home counties mayors
attended to discuss the coal outlook, and to promote as
far as possible further economies in the use of coal, gas,
and electricity. Sir A. Stanley, President of the Board
of Trade,, spoke at considerable length, and explained
that the serious shortage of 36 million tons of coal had
come about by the urgent necessity for the withdrawal of
100,000 men from the coal mines, the absolute needs of
France and Italy (seeing that France could not work
certain of their coal mines which were in the war zone
and Italy had no coal fields of her own), and the trans-
portation of American troops. Also another important
meeting was held on Monday in the Cannon-street Hotel,
when a large number of the London merchants attended
to meet representatives from all the various provincial coal
merchants’ societies relative to consolidating all the traders
in England and Wales into a great national federation.
Mr. E. Smallwood, M.P., presided, and a provisional
committee was elected to carry out the above object. The
stocks of coal in London were stated to be only 182,000
tons on August 31, whereas in March last there were
341,000 tons on the ground. From all sides there is an
enormously increased demand for household and manufac-
turing coal, and merchants report an absolute inability
to cope with the mass of orders in hand. Colliery sid-
ings are crowded with empties waiting to be loaded. The
winter contract price at all the collieries will come into
effect on October 1. The recent strike amongst the rail-
way employees had a very disastrous effect upon the
London coal depots. Many of the metropolitan coal
depots in London, notably Poplar Docks and Bow, were
practically isolated.

From Messrs. Dinham, Fawcus and Company’s Report.

Friday, September 20.—The arrival of seaborne car-
goes at to-day’s market was very small. No house coal
on offer. The demand still keeps good owing to the slight
change in the weather. Cargoes, 4.

Monday, September 23.—There was no seaborne*coal
on offer. The arrivals are slightly better, but wholly
on account of contracts, gas, etc. No seaborne house
coal is being shipped at the moment. Arrivals, 22.

Wednesday, September 25.—There was no seaborne
coal on offer at to-day’s market, the cargoes arriving being
on account of contracts. Cargoes, 14.

Miners’ President and Secretary.—Our mining corre-
spondent writes that the nominations for the first perma-
nent president of the Miners’ Federation of Great Britain
include Mr. R. Smillie (present president) and Mr. G. J.
Hancock, M.P., secretary of the Nottinghamshire Miners’
Association. Messrs. J. Robson (Durham), Harry Twist
(Lancashire), P. Pemberton (Lancashire), and J. Weir
(Northumberland) have been nominated for the office of
secretary in succession to the Right Hon. T. Ashton. The
nominations for the two offices close on September 30, and
the election will be by a ballot vote of the men.

Lord Aberconway and the Coal Shortage.—Speaking at
the annual meeting of the shareholders of the Sheepbridge
Coal and Iron Company, at Sheffield, Lord Aberconway
remarked that with 75,000 men combed out one could see
that it was impossible for the collieries to turn out 80
per cent, of the pre-war output. Though the percentage
of absentees was high, it was higher in 1911, and as the
output per man per day was higher now than before the
war, it was no use abusing the collier. The Government
was to be blamed for not facing the fact that every man
taken meant a reduced output. The last comb-out took
place at a time of great national difficulty in France,
but now that Americans were arriving in hundreds of
thousands, and as coal was being supplied for that army
as well as our own in France, it appeared to him that
there was very little justification for retaining miners in
the Army when they were so badly needed at home.