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DEPARTMENT OF SCIENTIFIC AND INDUSTRIAL RESEARCH.

MEMORANDUM ON THE PRESERVATION OF TIMBER IN COAL

MINES.

At the present time the shortage of timber supplies has rendered the prevention
of wastage in pit timber a matter of national importance. A large amount of
timber in mines, and especially in shallow coal-pits, requires to be replaced pre-
maturely because it- undergoes decay and consequently collapses. Such decay or
disintegration is, at least for the most part, caused by various fungi which permeate
and devour the wood, and often clothe its surface with a fluffy or cottony material
(" spawn "). This spawn, usually white but sometimes coloured, can rapidly grow
over the timber, walls or floor, and may even be broken off and transferred elsewhere,
and thus reach and infect sound wood.

These wood-destroying fungi also produce fructifications, which emit countless
microscopic germs (" spores "), which, conveyed through the air, may alight on, and
attack, pit-wood.

Two means of preventing loss through the decay of wood are possible : pre-
: i tine and remedial measures.

Thorough preventive measures are largely impracticable at present owing to
difficulties as regards machinery, materials and skilled labour. On the other hand,
remedial measures may be undertaken at once; and it is the main object of this
Memorandum to point out what they are, and how they should be employed.

A. Remedial measures are designed to decrease the amount of infection, so
that the life of pit-timber will be lengthened on the average, and a corresponding
saving be thereby accomplished.

Growth of the spawn over the surface of the timber, walls or floor to sound
wood is one means of rapid spread of infection, and is aided by the transference
of the spawn by other agencies (wind-currents, on men's clothes, packing of rejected
pit-wood close to sound wood, &c.). The checking of this superficial growth cannot
do more than diminish the rate of decay of the timber, because the wood-attacking
fungi grow also inside the timber; but inasmuch as the fungus grows more rapidly
outside than inside the wood, the rate of destruction of pit-wood will be decreased
by killing spawn on the surface.

Infection will likewise be decreased by the removal and destruction of the germ-
producing fructifications that emerge from the wood.

In order to accomplish these ends -

1. Colliery timber men should be taught to recognise the spawn and
fructifications.

2. Starting from the intake, and travelling with the air currents to the return
ways, the timber should be periodically inspected for fungus-material on the timber.
Where fungus occurs, the accessible pit-wood should be treated as follows :

(a) The apparatus required would be a pail, some cloths, a cloth or cotton
swab, a strong knife, and an antiseptic solution properly made up.

(12159.) Wt. 18285 G 7. 4125. 1/18. D & S. Q 2.

:-.: :': .-{frf T- he : ro"ll6'wing antiseptic substances are suitable and are arranged in order
of preference :

(i) Creosote, and various derivatives.*
(ii) Zinc Chloride.

(iii) Copper Sulphate (which should not be used where tin- mine-
water is rich in iron).

be removed by cutting away the portion of wood to which it is attached.
These should be placed in the pail, carried to the surface, and burnt
in the boiler fires. All waste timber lying in the roadways and
recesses should also be brought to the surface and burnt at once.
Instant burning is important, as a good deal of infection of sound
timber takes place during storage above ground because decaying
wood is allowed to lie about amongst it, and so the infection is spread
to timber originally sound.

The result of this would be to stop much of the infection that is
caused by microscopic germs (spores).

(d) At the same time or subsequently, the spawn on the surface of the pit-

timber would be dealt with as follows. Each man engaged would
carry a swab, the cloths and a pail three-quarters full of the antiseptic
solution chosen. All the accessible wood, including props, balks, crown-
trees, bars and collars, would be washed with the solution, and the
spawn removed. The solution and cloths would require to be renewed
from time to time. When possible, loose bark should be removed and
the bare wood washed over with the solution.

This treatment would serve both to check the growth of spawn over
the surface and to prevent its transference from one part of the mine
to another, and thus would hinder new infections. But a certain
amount of the antiseptic solution would be absorbed by the wood, and
on drying would leave on or near the surface a thin film of antiseptic
substance which would check the growth of any germs that might alight
on the wood.

A great deal will depend on the thoroughness with which these operations are
carried out. When once begun the treatment should be systematically and regularly
pursued, as these wood-attacking fungi grow rapidly and temporary neglect may
undo the work of months. The mine-timber should therefore be examined at least
once a month. The consequence of the treatment will be a steady improvement in
the condition of the mine-timber from the very commencement. It will, however,
be evident that one limitation to the beneficial effects will be due to the inaccessibility
of decaying wood packed under the roof above the balks, crown-trees, bars or collars.

B. The methods detailed above constitute a direct attack on the wood-des-
troying fungi, and are designed to reduce the loss occasioned by decay in mines that
are already infected. An entirely different method of dealing with the problem is
a defensive one, and involves the protection of the wood by rendering it immune to
infection by fungi.

Wood can be protected more or less perfectly from decay-inducing fungi by
coating or impregnating it with an antiseptic substance. The degree of protection
thus afforded depends upon the substance used and upon the depth to v.-'iich it
penetrates the wood. Mere superficial coatings are less efficient than injections to
some depth within the surface; while perfect protection is ensured solely by impreg-
nating the wood throughout.

. Various substances are very unequal in their power of conferring upon wood
resistance to fungal attack. In some coal-pits mere soaking with mine-water lengthens
the life of the wood; at the opposite extreme of efficiency is creosote, which confers
indefinitely long durability upon wood. The exact treatment to be adopted will
depend therefore on the circumstances of the case and particularly upon the time
during which the wood is required to remain sufficiently sound to be of service.

* Competent advice should bo sought as to these.

Superficial washes are applied by means of a brush; and when "this* or a'ny "other
method of application of the antiseptic is adopted, bark must be removed from the
timber before treatment. Somewhat deeper penetration is ensured by soaking the
wood for a longer or shorter time in the heated antiseptic solution. For this purpose,
timbers, before being taken down into the pit, should be soaked for at least 15
minutes in a tank of 10 per cent, zinc chloride at a temperature of 130 F., or in
creosote as hot as it can conveniently be used. When the props are put in position
in the ways, their tops where bruised by the hammer should be painted over with
the preservative, as infection often starts at these spots. For deeper penetration,
more prolonged soaking is essential, and the deepest penetration is ultimately secured
with greatest economy by pneumatic pressure (and the use of a creosoting plant) if
large quantities of wood require treatment.

Creosote and its derivatives, or zinc chloride, represent the most economic and
efficient antiseptics for use in mines. But a number of salts confer feebler resistance,-
and may be used where the wood has to last only a relatively short time before being
removed; among these are common salt, magnesium sulphate, certain mine-waters,
copper sulphate (not to be used where the mine-water is rich in iron) : iron sulphate,
sometimes recommended, should not be used.

This policy of replacing timber in mines by wood rendered more or less anti-
septic should be followed in all cases. When carried out in the most thorough
manner, it gradually brings the pit into a completely sanitary condition (for instance,
thoroughly creosoted pit props that when unprotected collapse from decay in a few
weeks will last for many years ; discarded creosoted railway sleepers similarly will
serve for indefinite periods as sound cross bars).

The precise method of dealing with mines in order to eradicate or decrease
decay of timber will vary somewhat in detail in different cases. In regard to this,
advice may be obtained from the Department of Scientific and Industrial Research.

Note.

The significance of wood-attacking fungi (and possibly certain bacteria) is not
confined to their destruction of timber, for during their growth they may produce
" black damp," and the amount of this gas that they produce is directly proportional
to their abundance and vigour.

PERCY GROOM.

Photomount
Pamphlet

Binder
Gaylord Bros.

Makers
Syracuse, N. Y.

P*T.JN 21, 1908

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MAR 31 19

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