IMPROVEMENTS IN THE PRESERVATION OF TIMBER
Year: 1873

page_text: LETTERS PATENT to William Alexander Lyttle, of the Grove,
Hammersmith, in the County of Middlesex, Engincer, for the
Invention of "IMPROVEMENTS IN THE PRESERVATION OF TIMBER”
-Sealed the 14th October 1873, and dated the 21st April 1873.
PROVISIONAL SPECIFICATION left by the said William Alexander
Lyttle at the Office of the Commissioners of Patents, with his
Petition, on the 21st April 1873.
I, WILLIAM ALEXANDER LYTTLE, of the Grove, Hammersmith, in
5 the County of Middlesex, Engineer, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE PRESERVATION OF TIMBER,"
to be as follows: 1
I boil the timber in a bath of creosote or dead oil of tar, the
temperature of which is maintained at or near the boiling point
long enough to convert into steam and so expel the watery con-

page_text: stituents of the sap, and I provide a receiver or condenser like
that used at coal oil works, or of the form herein-after described, for
the purpose of condensing any vapours which may distil from the
boiling creosote. It is not necessary that actual ebullition or active
distillation of the creosote should take place, because the boiling point
of that liquid being so much higher than the boiling point of water it is
only necessary to exceed the latter so far as to convert the water of the
woody structure into steam. By this means the wood is seasoned whilst
pickled at the same time with the preservative liquor, and if it is
allowed to remain in the creosote till the latter has become nearly cold
the vacuum caused by the condensation of the vapour remaining in the
cells of the woody fibre will cause the latter to absorb the creosote more
freely. Any tarry or heavy hydrocarbon oil remaining after the
rectification of coal or shale, tar or petroleum will answer, and it is an
advantage to add to the pickling liquid any of the well known solutions
of sulphur which are soluble in creosote or dead oil. Timber thus
pickled may be still further preserved from destructive action by
covering it, either wholly or at the parts most exposed to decay, with
layers of brown or other strong paper, canvas, or thin sheet iron, these
layers being thoroughly coated and cemented to the timber and to each
other by melted pitch, asphalte, or any of the existing fusible bituminous
cements, more particularly that specified in my Letters Patent of last
year, Numbered 31, and entitled "Improvements in the Preparation and
Laying down of Bituminous Asphalte for Pavement." These layers of
paper, cloth, or thin sheet iron, or other thin sheet metal, may be
superimposed separately or in combination, and they are intended to
form a permanent artificial bark impervious to the weather and
moisture. By rolling them round or otherwise applying them in several
layers to the timber they can be made to largely increase its strength
so that a smaller scantling of timber, or even timber made up of slabs
or pieces fagotted or cemented together with the same pitch or
bituminous material as is used with the aforesaid artificial bark, will
answer as well as a heavier solid timber. In the case of telegraph
poles, railway signal posts, and other posts set only partially in the
ground, this artificial bark may be made either to cover the entire pole
or may be confined to the protection of the wind and water line of the
The pole can also be
butt or any other points specially liable to decay.
capped in this way so as not to need the present metallic or other
roofs.

page_text: The notches now made in telegraph poles for the insertion of the
'cross arms which carry the wires not only weaken the timber, but give
admission to a deposit of water, and in order to avoid this injurious
practice it is desirable to mount the cross arms upon cast or wrought-
iron brackets nailed at the proper points to the pole, or secured thereto
by the clamping action of the arm bolt passing through such brackets.
These brackets may also be steadied by nails driven into the pole in
addition to the clamping action of the arm bolt, and their use will
perfectly obviate the necessity for cutting the artificial bark herein-
before mentioned.
The pickling bath in which the timber is boiled as described may be
provided with a receiver to condense the distilled vapours so as to admit
of the separation of the hydrocarbon and watery liquids by decantation,
or this receiver may be arranged with such a backward fall for the
condensed vapours that all the liquid formed in the receiver shall at
once run back to the pickling boiler where the water from its less
specific gravity will float harmlessly on the top.
In order to economize heat it may be desirable to arrange a series of
these boilers in a circle after the manner of the series of ovens known as
"Hoffman's Patent kiln," the flame and furnace gases being made to
pass under or through such a number as to give up the greatest amount
of heat. A similar plan may be pursued in dealing with the distilled
hydrocarbon and watery vapours, those produced in the hottest boilers
being allowed to pass into and so become condensed in those which are
at a lower temperature. The doors for regulating the course of the
fire gases underneath the boilers and the openings for communication
from one boiler to another throughout the series may be arranged
and worked in precisely the same manner as the flues are regulated in
Hoffman's kiln.
A brick arch cemented with any good close grained cement will
answer as a cover to cach boiler, more especially if the bricks have
first been made almost red hot and have then been cooled in a
bath of melted pitch, asphalte, or tar. As there is no internal pressure
very thin sheet metal will suffice when the latter is used for the
cover.
.
T...
tim the hailow on tanks from banonth the host mor ha

page_text: The artificial bark herein-before described may also be used as a
protective covering to timber treated with any other existing pickling or
preservative solution applied in any of the well known manners. It is
also peculiarly desirable as a covering for piles or other timber sub-
merged in water, and in this case the employment of thin sheet metal 5
as described is a further protection from the attacks of worms.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Alexander Lyttle in the Great Seal Patent
Office on the 20th October 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM ]
ALEXANDER LYTTLE, of the Grove, Hammersmith, in the County of
Middlesex, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-first day of April, in the year of
our Lord One thousand eight hundred and seventy-three, in the thirty- 1
sixth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said William Alexander Lyttle, Her special
licence that I, the said William Alexander Lyttle, my executors,
administrators, and assigns, or such others as I, the said William
Alexander Lyttle, my executors, administrators, and assigns, should at 2
any time agree with and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN THE PRESERVATION OF TIMBER," upon the
condition (amongst others) that I, the said William Alexander Lyttle,
my executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, should particularly describe
and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the a
Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said William Alexander Lyttle, do
hereby declare the nature of my said Invention, and in what manner

page_text: the same is to be performed, to be particularly described and ascertained
in and by the following statement :—
The boiling point of creosote or dead oil of coal tar is so much higher
than the boiling point of water that if any substance containing the
latter in a free state is boiled in a bath of the former liquid the whole
of the water can be expelled as steam, whilst it is at the same time
replaced by the creosote. Taking advantage of this principle as the
means of pickling timber in creosote or other heavy oil of coal and
seasoning it by one and the same operation I boil the timber in a bath
containing such pickling liquor, the temperature of which is maintained
at or near the boiling point long enough to convert into steam and so
expel the watery constituent of the sap, and I provide a receiver or
condenser like that used at coal oil works, or of the form herein-after"
described for the purpose of condensing any vapours which may distil
from the boiling creosote. Ordinary coal tar will answer by combining
the pickling of the timber with the ordinary process of rectifying the
tar, the latter operation being continued till the residual liquid around'
the timber is brought to the desired degree of exhaustion. When this
combined rectifying and pickling process is conducted in connexion
with any of the arrangements of apparatus herein-after described it'
must be provided that the distilled vapours from the tar shall pass
direct to the receiver in the usual way followed in such rectification.
It is not necessary however that actual ebullition or active distillation
of creosote should take place, because the boiling points of the tarry
liquids bearing that name are so much higher than the boiling point of
water that it is only necessary to exceed the latter so far as to convert
the water of the woody structure into steam, and if the wood is allowed
to remain in the creosote till the latter has become cold the vacuum
caused by the condensation of the vapour remaining in the cells of the
woody fibre will cause the latter to absorb the creosote more freely.
The same object is more readily attained by running away the charge
of boiling creosote into another tank freshly charged with timber, and
running a charge of cold creosote into the tank from which the hot
creosote was withdrawn. Any tarry or heavy hydrocarbon oil remaining
after the rectification of coal or shale, tar, or petroleum will answer the
purpose, and should be taken as implied wherever the designation
"creosote" is used in this Specification. In the case of railway sleepers,
fencing material, and telegraph poles it is desirable however to have as

page_text: much of the residual pitch as possible retained in the creosote, so long
as the fluidity of the latter in a boiling state and its power of penetrating
the wood by absorption are not thereby injured. The reason why such
heavy and impure creosote answers best is that although fluid when
boiling it becomes so far pasty when cold that it is not subject to waste
by filtering away from the timber in the course of time. Ordinary
creosote of commerce answers this purpose equally well if it has the
desired proportion of pitch, bitumen, or rosin, together or separately
added thereto.
Before boiling the timber in the creosote as described it may be
deemed desirable to impregnate it with any of the well-known aqueous
pickling solutions, such as solutions of the zincic, calcic, or ferric
chloride, or of hydrargic bi-chloride; also the solutions of cupreous
and arsenical salts applied according to any of the existing processes.
When timber thus treated is boiled in pitchy creosote the water con-
tained in the timber and in the solution of salt absorbed therein is
expelled as steam, whilst the preservative salt is retained throughout
the fibres. When timber thus salted and subsequently creosoted is
exposed to the weather it can no longer suffer injury through having
the soluble salt washed or dissolved away, because the pitchy creosote
absorbed by the wood will form a waterproof casing even when it has
been allowed time to penetrate only to a short depth. It is an advantage
to add to the pickling liquid any of the well-known oily solutions of
sulphur, but especially a solution of sulphur in the pickling creosote
employed, but never when tar is used under rectification. Timber thus
pickled may be still further preserved from destructive action by covering
it either wholly or at the parts most exposed to decay with layers of
brown or other strong paper, canvas, or thin sheet iron. These layers
being thoroughly coated and cemented to the timber and to each other
by melted pitch, asphalte, or any of the existing fusible bituminous
cements, more particularly that specified in my Letters Patent of last
year, Numbered 31, and entitled "Improvements in the Preparation
and Laying Down of Bituminous Asphalte for Pavement."
The object
of using paper, canvas, or other sheet material in this way is to facilitate
the spreading of the bituminous matter. in a thin and uniform layer,
but the same result will be attained with almost equal effect if the
timber when boiled in creosote rich in pitchy matter as described, or
when dipped in melted bituminous matter, is dusted thoroughly with or

page_text: rolled in any fine mineral dust or sand, either hot or cold. Successive
moistenings by the pitchy creosote or melted bituminous matter, followed
by successive rollings or dustings with the mineral powder, will give
greater body to the coating. These layers of paper, cloth, or thin sheet
metal, or of mineral powder alternated with coatings of pitchy matter,
as described, may be used in combination by being overlaid upon each
other, as may be desired, and they are intended to form a permanent-
artificial bark impervious to the weather and moisture. By rolling the
paper, canvas, or sheet metal around, or otherwise applying them in
layers to the timber, they can be made to largely increase its strength,
so that a smaller scantling of timber or even timber made up of slabs or
pieces fagotted or cemented together with the same pitch or bituminous
material as is used in cementing together the aforesaid artificial bark
will answer for some purposes as well as a heavier solid timber.
In the case of telegraph poles, railway signal posts, and other posts
set only partially in the ground, this artificial bark may be made either
to cover the entire pole or may be confined to the protection of the wind-
and-water line of the butt, or of any other points specially liable to
decay. The pole can also be capped in this way so as not to need the
present metallic or other roof. In the case of railway and farm fencing
timber, the best means of providing this bark covering round the laths
or light pieces of wood is by a coating of bituminous matter and mineral
powder as described above, and in most cases the butt and wind-and-
water line of each piece alone need be so covered.
The "
cross arms "which carry the insulators and wires are now
generally attached to telegraph poles by being set in grooves notched
into the timber and then secured by bolts, but as such notches weaken
the fibre of the wood, admit moisture, and break the continuity of the
artificial bark when that covering is used, I propose to substitute the fol-
lowing alternative method, namely, to nail cast or wrought-iron brackets
to such poles, fitting them thereto as saddles without notching, and to
clamp the cross arms home against the brackets and poles by means of
bolts, like those now used, which would pass through a hole in each
bracket as well as through the pole at that point. A cross arm thus
secured would be retained in a steady position by having its lower side
borne against the horizontal projection of the bracket, whilst the side
next the pole would be clamped against the outside of the saddle part of

page_text: the bracket, made here to fit the cross arm closely when it is bolted
home in the required position.
The pickling bath in which the timber is boiled as described may be
provided with a receiver to condense the distilled vapours so as to admit
of the separation and recovery of the hydrocarbon liquid by decanting it
away from the watery portion of the contents, or this receiver may be
arranged with such a backward fall therefrom for the condensed vapours
that all the liquid formed in the receiver shall at once run back to the
pickling boiler, where the water from its less specific gravity will float
harmlessly on the top. The latter cannot be done when the rectification
of tar is combined with the pickling process. I do not confine myself
to any particular kind of boiler or receiver, when the latter is used, in
preserving timber according to the principles hercin-before described,
but I find that a very simple as well as economical form of boiler for
the required purpose consists of a rectangular sheet-iron box or tank
with an opening at one end into the receiver, and a fire-place with fluc
to the chimney underneath in the way usually followed in mounting
externally heated boilers. The cover of this tank may be arched to give
it strength, and its edge along its four sides should overlap the sides and
ends of the tank so as to dip into a trough or gutter filled with creosote
which would be attached to and surround the top of the tank on the
outside. This simple "water joint" would suffice to keep the tank air-
tight because of the absence of any great internal pressure. By having
a travelling crane crected above such tanks, their lids can be readily
raised and removed by chains hooked to rings provided on the lids, and
the same crane arrangement will facilitate the loading of the timber into
the tanks, and its withdrawal when pickled. By loading the timber,
when not in heavy pieces, into suitable iron crates or skeleton frames,
large quantities or even whole tank charges can be disposed of by means
of the travelling cranes at one operation. When timber is placed in one
of these tanks it must be secured against rising by means of cross bars,
or in any other convenient way before the creosote is admitted.
In order to economise heat it may sometimes be desirable to arrange
a series of these boilers in a circle after the manner of the scries of
pottery and brick ovens known as "Hoffman's Patent kiln,” the flame
and furnace gases being made to pass underneath or through the flue
tubes of such a number as to give up the greatest amount of heat before
escaping into the chimney shaft. The doors or valves for regulating the

page_text: course of the fire-gases which heat the tanks should also be arranged
and worked in precisely the same manner as the similar doors or valves
are regulated in the "Hoffmans' Patent kiln." For instance if A, B, C,
D, and E are a series of tanks so arranged in a circle, and all charged
but E, the smoke flue under D is cut off by a valve from E, and oen ed
direct into the chimney, at the same time the fire being lighted under
the tank A the hot gases or smoke pass thence under B, C, and D,
giving up the whole of their heat on the way. When A is sufficiently
boiled the fire is withdrawn thence to B, and E being then charged with
timber and pickle is placed in the series by cutting off D from the
chimney opening the flue from D into E, and from the latter into the
chimney. Whilst the charge in B is being boiled, the tank A is
emptied and recharged with timber and creosote. The next change is
to remove the fire from B to C, and also to include the last charged
tank A in the course of the smoke to the chimney by cutting off E from
the chimney, opening the valve between E and A, and the valve between
A and the chimney.
When the rectification of tar is combined with the process, each
tank, acting as a retort, must send its vapours direct to the receiver;
but when croesote only is employed an exactly similar arrangement of
valves for connecting the upper or creosote portions of these tanks
with each other and with the chimney should be provided, and by this
means whilst all exhalations from the boiling tanks are drawn away to
the chimney they are certain to deposit in their course throughout the
series everything condensible before reaching the valve or door at the
tank last charged, by which egress into the chimney is allowed. This
general statement will suffice to shew to any one acquainted with
Hoffman's Patent kiln how perfectly its arrangements are applicable in
all respects to the purposes of this Invention.
A brick arch cemented with any good close grained cement will
answer as a cover to each tank or boiler where a moveable iron cover is
not preferred, and in this case bricks made hot and then dipped in hot
melted pitch or tar, and cemented together with a dense close grained
cement will answer best.
In adapting the Hoffman kiln principle the side and ends of the iron
tanks may be raised by continuations of brickwork thus prepared, and
in these sides and ends may be fitted the valves connecting each tank

page_text: with the chimney and with the adjacent tanks. A sheet or cast-iron lid
may still be provided overhead for cach tank if desired, as well as a
circular travelling crane for charging and discharging the contents.
For the purpose of affording greater protection from the boring of
white ants and other insects, in the case of timber covered by the afore-
said artificial bark, it may be desirable to saturate the paper, canvas, or
mineral dust about to be used for such bark with a strong solution of
hydrargic bichloride, and then to dry it before it is applied to the wood,
as herein-before described.
GENERAL PRINCIPLE OF THIS INVENTION AND CLAIMS.
In order to define more exactly the nature and extent of my claim as
regards the Invention herein-before described, it is necessary to point out
more fully the distinctive features of the process as compared with other
methods of attempting the preservation of timber by the use of creosote.
I have recently been made aware that about twenty years ago some
private experiments were made with the view of saturating the sub-
stance of timber with creosote by boiling it in that liquid, but that they
were abandoned as useless because no large amount of creosote could be
thus introduced into the wood to a greater depth than the mere surface.
I would therefore explain that I do not seek any such result, and that i
in all my arrangements I treat the surcharging of the timber by creosote
which is aimed at specially in the well-known "Bethel " processes as
useless so far as the mere saturation of the timber is concerned. On
the contrary I find that the limpid description of oily creosote best
adapted for the "Bethel" or high-pressure process is of the least value
for mine, as herein-before specified, because of its tendency to filter
away from the timber in the course of time, and I therefore use either the
impure residue from the rectification of coal tar, containing creosote and
pitch together, or I add pitch to the creosote of commerce to make it
more suitable to produce the best result under my plan.
It is well known that every existing method of applying creosote to
timber is useless if the timber is not dry when the creosote is employed,
and that the moisture confined within the substance of the timber by the
hydrocarbon oil exercises its destructive power upon the woody fibre
unchecked in any degree by the presence of the oil or creosote. It is
therefore clear that creosote possesses very slight or no antiseptic power

page_text: calculated to arrest and suspend the chemical action induced by the
presence of moisture already in the fibre, and I conclude that its chief
use is to prevent the admission of further moisture by reason of its oily
nature, and thereby to check decay if the wood is seasoned, which in the
case of railway sleepers and telegraph poles is rarely the case. For this
reason I take it as obvious that the mere saturation of the whole mass
of the woody fibre by creosote, as accomplished in the Bethel high-
pressure process, is only a waste of material, because a small proportion
of the creosote thus required, when applied under my process to the
boiling therein of the wood, will suffice to expel the whole of the
destructive moisture, whilst charging the outer surface at the same time
in every crack and pore with a solution which congeals when cold into a
perfectly waterproof cement. During the boiling of the timber the
carbolic acid of the creosote exercises an increased power of diffusion or
penetration into the timber as the vapour of water is escaping, and thus,
no doubt, exercises some preservative effect. These results are fully
realised in the combined processes of boiling the timber in coal tar and
rectifying the latter at one and the same time, as already described. The
same results are also realised with equal economy and advantage if the
timber is boiled in the residual liquid, consisting of a mixture of dead oil
or creosote and pitch, which can be run off from the retorts used in rec-
tifying coal tar or petroleum after the more volatile constituents have
been removed therefrom by distillation in the usual way.
Having now described the nature of my Invention, and the best
means known to me for carrying the same into effect, I wish it to be
understood that, without restricting myself to the precise details herein-
before specified, what I claim is,―
Firstly. The simultaneous pickling, seasoning, and surface water-
proofing of timber by boiling it in the pitchy creosote of coal or
petroleum tar, or in any other heavy hydrocarbon oil, with which there
is incorporated rosin, pitch, or other bituminous matter.
Secondly. The boiling of timber for the same purpose in tar, by com-
bining the process of pickling the timber with the usual method of
rectifying the tar, as herein-before described.
Thirdly. The use of a solution of sulphur incorporated with the hydro-
carbon pickle, as described.

page_text: Fourthly. The application of the process referred to in the above first
claim to timber which has been previously treated with an aqueous
solution of any preservative salt according to any known process.
Fifthly. The closing of the cracks and pores of the surface of the
wood, when desired, by means of an artificial bark, made and applied as
described.
Sixthly. The use of hydrargic bichloride in the preparation of the said
artificial bark, as described.
Seventhly. The use of the well-known beating arrangements of
"Hoffman's Patent Kiln," and also of the various other details, although
I do not limit myself thereto as regards the tanks or boilers, for the
purposes of this Invention, substantially as herein-before specified.
In witness whereof, I, the said William Alexander Lyttle, have
hereunto set my hand and seal, this Eighteenth day of October
in the year of our Lord 1873.