1162

THE COLLIERY GUARDIAN

December 15, 1916.

cutting all their timber in a ‘wood just near the mine,
and in less than no time after it had gone into the pit
the place looked as if it had been whitewashed. He
would like to ask if the fungi attacked unseasoned wood
with greater ease than seasoned, and if the fact that the
bark was on made the wood more susceptible to attack.

Mr. Mitchell, in reply, said the question of a cheap
method of treating timber before it went into the pit
would undoubtedly have to be investigated. His
impression was that the only method Which had been
really successful was the pressure treatment by creosote,
but it was very expensive. It was of the greatest
advantage in roads that they wished to preserve for a
good number of years, but in cases where they only
wanted to maintain them for three or four years, the
expense was a very serious matter. He believed that
if the measures which he had suggested were adopted,
the mine would, in course of time, be in such a condi-
tion that it would be possible to get the present life of ■
impregnated timber equalled by timber which had
merely been dipped in creosote, and dipping would, of
course, be infinitely cheaper than the pressure process.
At present, if they put creosoted timbers or any other
timbers into a mine, they were simply putting them into
a hotbed of disease; but in course of time they would be
able to put them into a mine which was comparatively
free from infection through the ventilating current and
through mycelia. Dipping the timber would give an
impervious coating which would kill all the spores pre-
sent on it, thus more or less sterilising it before it went
into the mine, and, with the conditions in the mine
improved, such timber was likely to last just as long as
those which now had to be completely impregnated,
owing to the serious condition in the mine itself. As
regards timber outside the mines, no doubt a certain
amount of infection took place there. If they left
timber lying about in the yard, and timber which had
been brought up out of the mine was also left to lie
about, then a short time—a fortnight or a month—would
be quite long enough to allow whole stacks of timber to
be somewhat seriously infected by spores before enter-
ing the mine, and, immediately it got in, the warmth and
moisture would cause them to develop. With regard to
the timber in the roof, of course, the scientist could
not overcome the practical difficulty; that rested with
the mine people themselves. But what he believed was
that the saving effected by methods of the description *
he had suggested, would eventually be so great that all
practical difficulties should be overcome. Nothing was
impossible if they were determined to get rid of the
trouble. He believed that the cost of cleaning up the
mine would not be as great as the cost of replacing the
timber was at the present time. That item was, he
believed, very expensive. If they only preserved their
timber one year they would gain a great deal, but he
thought that they would preserve it in steadily increas-
ing proportion from year to year. Replying to the ques-
tion as to British timbers with the bark on, he said
there was no doubt that such timber did not last as long
in the mine as that from which the bark had been
removed. This was largely because certain fungi parti-
cularly attacked timbers which had the bark remaining
on. Further, the bark, in cracking, exposed sections of
the wood which had been kept damp by the bark itself,
and thus the wood was in a condition more susceptible
to infection from spores and fungus threads. Threads
would penetrate more easily timber which had the bark
on than timber from which the bark had been removed.
Unseasoned timber would unquestionably be infected
earlier than seasoned; not because the unseasoned timber
was wetter, but because all the food material which was
in the tree at the time of its felling was kept there in
more or less its original condition, and the fungus had a
rich ground on which to feed immediately it touched the
wood. If timber was seasoned properly, the carbo-
hydrates, sugars, and so on, were all broken down, and
often converted into resins and tannins, which in them-
selves had resisting powers against fungi. Therefore,
by seasoning alone, he believed that they gained a very
much longer life for their timber. It was very unwise
to use unseasoned timber, as they simply had quick
decay and rapid infection.

Mr. Kirk (Sheffield) said it might be of interest to
mention that there was a method by which timber could
be rendered immune from attack by fungus, by soaking
it and letting it become impregnated with a solution.
His firm were taking some interest in the process before
the war, but as it was an Austrian process, they dropped
it when the war broke out. He was not clear as to the
chemical name of the solution at the moment, but he
would be glad to communicate it to Mr. Mitchell or
anyone else who was interested. They found that the
cost would run out to about 3d. or 4d. per cu. ft. As '
timber at that time was far cheaper than it was now,
they were not so keen about the matter as they would be
at present.

Supplies of Refractory Materials Available in the
South Yorkshire Coal Field.

Prof. W. G. Fearnsides then read his paper on this
subject. (See page 1159.)

Discussion.

The President said the lecture had been the most
interesting that he had ever listened to on the subject
of the manufacture of bricks. The importance of the
question had come home to them very much during the
last 20 years. TThey knew what trouble they used to
have when the first ovens were started in the district,
and he wished they had had Prof. Fearnsides to lecture
to them 20 years ago. It would have saved them vast
sums of money, and saved their tempers as well.

Mr. Hinchliffe (Bullhouse) said he was connected
with the bad qualities of coal in the lower measures,
and hitherto the Proceedings of the institute had mostly
related to the valuable coals in the middle and upper

measures. He was very pleased that Prof. Fearnsides
had gone to the trouble of elucidating a great many
things in connection with the lower measures, which
had been very much neglected in the past. The
lecturer had passed very lightly over the question of
their crude methods of working. He (the speaker) must
attribute these methods to the poor financial results that
they obtained. They were really unable to work on
scientific lines, such as were adopted by the other coal
people in Yorkshire. With regard to the outcrop clays
being more serviceable than those found under pressure,
owing to the presence of sulphur in the latter, it only
proved that the old system was right, and that they
wanted their clays well weathering. He thought that
i'f clays which were got from a very deep position, and
contained a large amount of sulphur, could be given a
few years to weather in—a practice which the Chinese
used to carry out—the same conditions could be brought
about which obtained in the outcrop clays. Prof.
Fearnsides had evidently not gone very extensively into
the investigation of the clay coal that he referred to.
He spoke very well of the pot clay and the coking coal.
The clay coal, between that and the Halifax hard bed,
was, he (the speaker) believed, found in practice to be
one of the purest clays that they had, and he thought
there were great possibilities in that particular seam.
Both the coal and the clay of the underseam 'were parti-
cularly pure. They found the Halifax hard bed very
constant, as the lecturer had said, but the seating was
very inconstant. They might have a deposit of the best
quality, containing perhaps 95 per cent, or more of
silica, and, within a yard or two, an aluminous deposit.
That was one of the reasons that prevented the
systematic working of the mines. They had to leave
certain parts that did not pay, and work those on which
they could get some return. The 36 yd. clay was, as
found in their district, one of the safest clays. He was
very much interested to know that the contraction and
expansion were equally balanced in that clay. He had
only used it in mixtures, so that the point brought out
by the lecturer was one that he had not been able to
prove. The statement that there was more hope at the
bottom end of the coal field was, he thought, very
correct. Recently, he had had occasion to be on some
of the millstone grits on the moorlands, and he had
noticed, from the escarpments and rivers, several beds
of clay which had no name that he knew of, and which
were below some of the millstone grits. He felt sure
that developments would take place from these clays,
if they were properly investigated. The question of
dolomite was more for the investigation of those
interested in the upper measures than for himself, but
he believed there were very great possibilities in that
direction. He proposed a vote of thanks to Prof.
Fearnsides for his most interesting lecture.

Mr. Coultas (Deepcar) endorsed what Prof. Feam-
sides had said as to the peculiarity of pot clay being of a
much better quality on the outcrop than where it was
considerably covered. His experience with most
refractory clays was that when they were exceedingly
good on the outcrop, they became much inferior as the
cover increased, probably on account of the greater
pressure. The blackness in the clay, when burnt into
the brick, was attributed by the professor mostly to
sulphur, but probably if he went further into the manu-
facture he would find that it was not altogether that,
but that a considerable portion of the trouble was due
to the manufacturing part. The lecturer had spoken of
possibilities in the coking coal, but his (the speaker’s)
experience was that there was not much hope in that
direction. There was too much fluxing material in the
coal. It would answer for some purposes, but not for
refractory material, or, if it did, it would have to be
doctored considerably. It might be manufactured into
sanitary ware, in which conditions were wanted that
were the reverse of those needed in refractory material.
For the latter, they required something loose and open,
whatever the temperature used, but that was altogether
unsuitable for sanitary work, where a vitrifiable and
close material, which would resist the evaporation of
moisture, was required. The middle bed clay was one
of the most erratic that he had ever come across. He
was familiar with the clays from Bradford, Leeds, and
Halifax, down to South Yorkshire. In some places this
clay was “ out ” altogether, and in others it was excel-
lent for sanitary ware, but so far he had never been able
to make it suitable for refractory material. He had
mixed it in various proportions, but on submitting it to
a very high temperature, he had always found that it
vitrified where it ought to have kept open. The peculi-
arity about the ganister field was that where the ganister
was thick they generally found the coal very thin—in
some cases almost absent—while, where the coal was
thick, the ganister was thin, and of very much poorer
quality. It would be interesting to know why that
should be so; but so it was, and they would find it all
over the coal field. Up Halifax way, where the coal
was thicker than in South Yorkshire, the ganister was
practically absent. The fireclay above the Halifax hard
coal band was most excellent. The lecturer had not
exaggerated its quality in the least. Its chemical com-
position was somewhere about 60 per cent, silica and
27 to 30 per cent, alumina, which was an ideal mixture
for refractory purposes. The works with which he was
connected produced from that clay firebricks which
would stand 28, 30, or even more heats in a ladle con-
taining 40 tons of molten steel. That was acid steel;
with basic steel the bricks would stand perhaps one-
quarter that number of heats. Going upwards through
the measures, the next refractory clay that he knew was
the one which underlay the Lowmoor Better bed. In
some cases a very good refractory clay was found under
that bed, but in other places it was absent. As to the
clay underlying the black bed, he did not know that he
had ever seen that used for refractory purposes at all.
He seconded the vote of thanks, wliich was carried.

Mr. G. Blake Walker said one point which had not
been emphasised perhaps quite as much as it might be
was our backwardness in this country in blending clays,
analysing them, and finding out the constituents which
were adapted for the purposes required, and then
makfrig w’hat might be called artificial firebricks. He
believed that a great many of the imported bricks which
were sometimes used in connection with coke ovens, and
were supposed to be more satisfactory than our own,
were largely the result of skilful blending, and this was
an industry which deserved more attention and
encouragement in this country than had been given to
it in the past. He believed that the celebrated Scotch
Glenboig fireclay had been largely sent over to Belgium,
and returned in the form of an improved firebrick, which
bore the cost of transportation to and fro. That kind of
thing might just as well be done in this country, and the
cost of all the conveyance saved. It was evidently a
science which was somewhat neglected in this country,
if not in its infancy. WTe seemed to have the raw
materials, but did not know ho>w to use them. We were
going on in the most primitive manner, just using the
clays as we found them, and we should be driven, by
the exhaustion of the outcrop beds, to go under a greater
amount of cover, and to obtain the necessary condition
and constituency of the clays by treatment. It was
just as possible as it was to have chemical combina-
tions applied to the preparation of certain products. They
knew how the introduction of rare metals had entirely
altered the quality of steel. High-speed steel had been
made possible by the results of scientific blending and
combination. That might seem to be too scientific a
way of dealing with such a very simple product as fire-
bricks, but, in a place like Sheffield, firebricks were a
condition of the successful manufacture of steel, and, as
new processes were evolved, new refractories were
required to suit them. He had never heard, until Prof.
Fearnsides told him, that there were such things got in
that neighbourhood as dolomite bricks. Evidently that
was an industry which must come to the front, and he
believed there were some extremely valuable beds from
which the very best of refractory material could be
obtained.

Blending and Preparation.

Prof. Fearnsides, replying to the discussion, said he
was quite in agreement with Mr. Blake Walker that very
considerably greater success would probably be attained
when they had learned how to blend their clays. He
was not sure, however, that the haphazard blending of
clays would give results particularly analogous to the
results which were attained by the blending of alloys in
the making of alloy steels. In general, when they
mixed materials in the making of bulky stuff like refrac-
tories — materials which were themselves already
chemical compounds—they got something which was a
little analogous to the effect obtained by mixing salt with
water. Salt was a material which melted at a fairly
high temperature. Water was a material which melted
at freezing point. But if they put a bit of salt with ice,
they knew that the melting point of the water went
down. In general, in the making of refractories, one
of the most important principles that they had to go on
was to see that the materials which they manufactured
were simple chemical compounds, which had definite
melting points, and definite physical and mechanical
properties. Most oxides were refractory, whether they
were acid or basic, and certain intermediate clays were
also refractory, but only those which were so consti-
tuted that they became definite chemical compounds
when fired. It did not at all follow that by putting in
a little bit of this and a little bit of that, they would in
every case improve the refractory properties of the mix-
ture. It was, however, a matter that was well worthy
of a great deal of scientific research. In trying to help
steel manufacturers in their choice of materials for the
lining of the furnaces, he had had to learn a very great
deal, and one of the things that had come to him very
forcibly indeed was that refractory materials ought to be
studied by almost exactly the same methods that were
always used for the study of steel. They wanted to
know not only melting points and chemical composi-
tions, but also a good deal about heat treatment, the
changes that occurred in quartz just as in steel, the
temperatures above which refractory material was in one
physical state, and below which it got into another.
These matters ought to be studied with very consider-
able care. With regard to the question of outcrop clay
raised by Mr. Coultas, he thought that progress would
eventually be made by copying Nature, and preparing
clays. If, between bringing the clay out of the mine
and taking it to market, they could allow it to stand
idle for four or five years, stacking it on the surface,
and letting it get weathered, he believed the result would
pay interest on the capital. He believed, however, that
there was a time coming when they would do, perhaps
in a few days or a few hours, what Nature did in a
series of thousands of years. What prohibited that at
present was the cost of getting water into the clay and
then getting it out before the clay was put into the
kiln. Those people who made pressed bricks, and were
able to take the clay dry as it came out of the mine,
turned their bricks out of the mould and out of the kiln
at a very much less cost than those who had to puddle
their clay, to leave it over winter to get the frost in,
turn it over next spring, and turn it back again. Though
the brick from the weathered material was probably
better in the end, yet, balancing one thing against
another, the maker of refractory materials was only too
keen to get the stuff straight from the mine into the
brick. If they were going to improve the materials that
they got in the deeper mines, he was certain that they
would have to mix all their clay adequately into a
puddle. It would have to be treated as a puddle, or
perhaps as something more slimy, like liquid mud—
perhaps with electricity, perhaps with doping. An alkali
would have to be put in, and, when mixed, it would have