1274

THE COLLIERY GUARDIAN.

June 13, 1913.

more certain samples would be obtained of the contents
than could be obtained in the other way.

Mr. F. H. Bailey asked the author whether any
temperatures were taken down towards the gob-fire,
because it appeared *to him that one of the important
questions which would affect the diffusion of the
gases would be the heat that was given off at the
bottom of the working through the gob-fire, and
possibly that might affect the diffusion of the gases at
the dips. It was well known that a dip working was
very much easier ventilated than a rise, and that the
light gases would come to the top of the dip ; but what
would be the effect of the heating of the atmosphere at
the bottom of the dip causing the gases to diffuse ?

Dr. J. S. Haldane desired to express his extreme
admiration for the way in which the very important piece
of work described had been carried out by everyone
concerned. He thought it was by far the biggest piece
of work that had ever been carried out with an appa-
ratus of the kind mentioned. He also wished to lay
stress on a point to which some of the previous speakers
had referred but had not emphasised—namely, the value
of the chemical analysis. He also wished to be allowed
to express his admiration of the cool, collected and
determined way in which the men who used the appa-
ratus evidently went about their work. The question
of the supply of oxygen to the apparatus was a very
interesting one, which he had had to reconsider lately
in connection with the rescue apparatus of the London
Fire Brigade. The apparatus was recently tried at the
Fire Brigade Station, and it was found that 2 litres of
oxygen was not sufficient. He walked a man with the
apparatus on up and down the yard until he got blue in
the face and was just tottering over, so that it was
evident 2 litres were not enough. Two litres were
sufficient for ordinary mining work ; but a man could
easily consume more than 2 litres if he walked fast. If
there was only air in the bag to begin with, a man was
very apt to get short of oxygen, and where a good deal
of heavy work had to be done more than 2 litres were
required. He did not think it was possible to cut down
the 2 litres which were ordinarily used for mining work.
Nothing had impressed him more lately than the need
for not only thorough training and experience, but
knowledge, which was everything. A man could not
dare to play tricks with the apparatus ; he must have
everything tight. The men must be extremely careful;
they must be thoroughly trained and thoroughly
intelligent, and know what they were about—what gases
were, and what they could do and what they could not
do.

Mr. W. 0. Blackett desired to be allowed to ask Dr.
Haldane a question in reference to the point with which
he had been dealing. It had occurred to him once or
twice in dealing experimentally with the apparatus
whether the size of a man’s lungs had not a lot to do
with the amount of oxygen that he required. He
would like to know whether a man with little lungs
would not live more comfortably in the dress than a
man with big lungs.

Dr. Haldane replied that there was no doubt a
difference in the amount of oxygen which different men
would consume in doing the same amount of work. If
a man walked at a fast rate along a street he consumed
something like 10 times as much oxygen as if he were
sitting quietly in a chair. Some people, however, would
consume only eight times as much, while others would
consume 12 times as much, so that there were individual
differences. The question of how much oxygen a man
consumed was not due entirely to the lungs, but to the
tissues and also to the amount of work that was being
done. A man who was trained could walk at a great
pace with very much less consumption of oxygen than
a man who was not trained, who threw his muscles
about and wasted his energy on unnecessary movement.

Mr. John Gibson asked Dr. Haldane whether, in his
opinion, the sickness which had occurred in one case
was due to the use of the apparatus.

Dr. Haldane replied that he did not profess to be
able to answer the question. All he could say was that
from his own experience with the use of oxygen he had
never had any trace of sickness, and he did not know
why the individual in question should have had any.
Offhand he was under the impression that it was a mere
accident. The sickness was probably due to the fact
that the man had eaten something that did not agree
with him. That was usually the reason.

Mr. A. L. Lovatt said he was the unfortunate
individual who happened to be sick on the occasion in
question. The sickness was not due to any fault in the
apparatus. Mr. Greatbatch sent over a special mouth-
piece which had on the inhaling side a diaphragm which,
it was thought, would prevent the saliva from getting
into the breathing bag, but, instead of doing so, it got
back into his mouth, with the result that he was sick.

The Slow Combustion of Coaldust.

The President, in calling upon Mr. Lamplough to
read the next paper, remarked that it formed an epoch
in the history of the institution, inasmuch as for the
first time a lady was one of the contributors. The
following paper was then read :—“ The Slow Combus-
tion of Coaldust and its Thermal Value,” by M. E. E,
Lamplough, M.A., Trinity College, Cambridge, and
A. Muriel Hill, B.Sc., Newnham College, Cambridge*

The President, in proposing that the best thanks of
the institution be accorded to the authors for their very
valuable contribution, said it was impossible to estimate
the importance of the subject with which it dealt. The
difficulties that had been experienced in connection
with coaldust for some years were nothing compared
with the difficulty of dealing with spontaneous com-
bustion, and he thought, in the first instance, the
laboratory, bearing in view the practical experience
already possessed, could help in pointing out what
investigations should be made.

Mr. W. C. Blackett said he desired to have the
pleasure of seconding the motion. Several little ideas
had struck him while the paper was being read, not the
least of which was the extremely sensible way in which
it had been placed before the members. In view of the
beautiful apparatus which Mr. Lamplough had described,
he thought that both Miss Hill and Mr. Lamplough
would make good colliery engineers. The only thing of
which he was afraid was that as oxygen was being so
severely attacked, a law might be passed to do away
with the use of oxygen in mines altogether.

The resolution was then put and carried with
acclamation.

Mr, G. J. Binns said one point that occurred to him
was that for 40 years people had been taking away and
restoring the character of iron pyrites as a cause of
auto-ignition in mines, and he was afraid from what he
read that at last the character of iron pyrites was hope-
lessly gone, and that to it must be attributed a great
deal of the trouble that occurred in mines that were
cursed with spontaneous combustion.

Mr. D. A. Louis said he did not think the question
was closed. As far as he could gather from Mr.
Lamplough’s remarks, he confirmed both sides. The
experiments proved, as all the members had known,
that there was a considerable amount of temperature
developed from iron pyrites. The point of confirmation
in the present paper was the statement that the oxygen,
in the absence of iron pyrites in the coal, did not
produce so much carbonic acid, remaining absorbed in
the coal. That, the authors would appreciate, meant a
considerable compression of the gas. The gas was com-
pressed, and when it was in that condition, without any
chemical action, it caused a rise of temperature.
Personally, he did not believe that it was at all possible
for pyrites to give rise to spontaneous combustion, the
temperature attained by the slow oxidation of iron
pyrites being, in his opinion, insufficient; but he quite
believed it might assist spontaneous combustion.

Dr. J. S. Haldane thought the result obtained from
the paper closed the controversy as to the approximate
amount of heat produced by oxidation in mines. There
was no direct calorimetric evidence in regard to it
previously. In the paper written by Meachem and
himself the hope was expressed that they might be able
to carry out the experiment and obtain calorimetric
results. The authors had succeeded in obtaining the
very difficult measurement of the heat produced at low
temperatures by the sort of oxidation which was going
on every day and everywhere in a mine. With regard
to the question of the relation of iron pyrites, he could
not agree at all with the remark of the last speaker that
the oxidation of iron pyrites might probably have
nothing to do with the fires. He thought so until he
visited Talk-o’-th’-Hill Colliery and saw the vast amount
of sulphate of iron that was lying about. The mine was
full of chemicals, the products of oxidation of iron
pyrites. There was certainly in many coals enough of iron
pyrites to heat the coals to such a serious extent that
all the other oxidisable substances would join in a gob-
fire. He thought that iron pyrites very likely had a lot
to do with many gob-fires. The heat produced was
about 25 per cent, less than Meachem and himself
calculated as probable in their paper on the subject. It
was now possible to calculate out very easily the total
heat produced in a mine simply from an analysis of the
upcast air, knowing the volume of the air—the heat
corresponding to the actual oxidation going on. The
calculations could be made on a fairly sound basis.

Mr. J. W. Fryar said he wished to say, on behalf of
the Doncaster coalowners, they were very pleased
indeed that some result had already been obtained from
the investigations. Twelve months ago, owing to the

* An abstract appeared in last week’s Colliery Guardian.

difficulties from gob fires in the Doncaster district,
some of the coalowners decided to have the subject
very fully investigated, and they were fortunate enough
to secure the services of Dr. Haldane in directing the
investigations. In order to make the fullest possible
use of Dr. Haldane’s time and experience, they expressed
the hope that where there were special subjects which
could be investigated as separate subjects, altogether
apart from the general investigations, that was, where
scientific data and information were required, Dr.
Haldane would engage the very best talent and apparatus
and the best people to carry out those special investiga-
tions. The paper was the result of one of the first of
the investigations, and he hoped it would not be the
last.

Prof. L. T. O’Shea thought the paper was one of
extreme importance, as it started a method which might
enable mining engineers, when a new seam had to be
worked, to deal effectively with the question of pre-
dicting how that new seam would behave under the
action of air. The present paper was remarkable for
the statement in regard to the large amount of carbon
dioxide which was produced when oxidation of the
pyrites which was associated with the coal took place,
and doubtless Dr. Haldane’s and the authors’ explana*
tion was the right one. The question could very largely
be settled if some means were taken to ascertain how
much the amount of ferro-sulphate or sulphuric acid
increased during the process of oxidation. That would
not be chemically a very difficult point to determine,
and if it could be shown that there was a distinct
relation between the increase in the amount of sulphuric
acid produced by the oxidation and the amount of
oxygen absorbed in the carbonic acid produced, that
would go very largely to show that iron pyrites was
playing a very important part in the oxidation of the
coal.

Mr. D. A. Louis said he did not wish to convey the
impression that iron pyrites did not oxidise. He asked
whether it would be possible for the authors to treat
their powder, or the hydrochloric acid, and remove the
carbonates, and then see if any CO2 was given off. That
was an easier way of carrying out the work than looking
for the ferric or ferro-sulphate.

Prof. Henry Louis agreed with Dr. Haldane that
the paper was exceedingly valuable, because it gave
numerical data for what were, up to the present, vague
observations, so that they now knew definitely the
amount of heat produced by the absorption of oxygen.
But the members knew something more which was of even
greater importance—namely, the rate at which absorption
took place. If he followed the paper correctly, he noted
it was a coal that was particularly low in pyrites which
seemed to give the most rapid rate of heat evolution.
With regard to the controversy as to the part played by
pyrites in the heating of coal, he remembered very
clearly the results of a very important Commission
appointed by the New South Wales Government which
dealt with the question of the heating power of coal
cargoes at sea, where it was proved to his mind conclu-
sively that cargoes of coal that were not pyritic in the
ordinary sense of the word were among those most
liable to firing ; that a cargo of coal very low in pyrites
was among the most dangerous cargoes one could
have, not because it was low in pyrites, but simply
because it happened to be so. The truth lay between
the two extremes. He was quite convinced in his own
mind that coal as free from pyrites as any coal could be
was liable to spontaneous combustion, but, on the other
hand, he believed that coal containing pyrites would
very often have its heating powers accelerated by the
presence of the pyrites. The authors had not, to his
mind, taken into sufficient account the difference
between the two kinds of pyrites that existed in coal—
the cubical pyrites and the coxcomb pyrites. The
former was pyrites which was not affected for years;
the latter oxidised very rapidly indeed, as anybody who
had ever had a specimen in his mineral cabinet knew to
his cost. It rather hurt his feelings as a chemist to find
it stated that iron pyrites was giving off carbonic acid
by oxidation. He would like to have an analysis of the
iron pyrites to see it. There was no doubt that, together
with combination and absorption, a certain amount of
dissociation took place. For instance, the coal which
contained marsh gas was under very great pressure;
marsh gas was evolved, and cooling was thereby pro-
duced. There were dissociation actions which must also
produce cooling, and it was quite easy to account by
several of those cooling actions for the lower evolution
of heat than was expected, as Dr. Haldane had stated.

Mr. John Gerrard desired to say how very much
indebted the members were to Dr. Haldane for the great
help he gave to practical mining men. One point was
now absolutely clear to his mind—namely, that there
were two causes operating to bring about the fearfully