CERTAIN IMPROVEMENTS IN IMPREGNATING WOOD WITH PRE- SERVATIVE AND COLOURING MATERIALS, AND IN APPARATUS FOR THAT PURPOSE
Year: 1856

page_text: LETTERS PATENT to Charles Cowper, of 20, Southampton Buildings,
Chancery Lane, in the County of Middlesex, Patent Agent, for the
Invention of "CERTAIN IMPROVEMENTS IN IMPREGNATING WOOD WITH PRE-
SERVATIVE AND COLOURING MATERIALS, AND IN APPARATUS FOR THAT PURPOSE."
-A communication from the late Henri Boucherie, of Bordeaux, in'
41France.
PROVISIONAL SPECIFICATION left by the said Charles Cowper,
the Office of the Commissioners of Patents,' with his Petition, on
14th February 1856,
:
: : :
at
the
I, CHARLES COWPER, do hereby declare the nature of the said Invention for
CERTAIN IMPROVEMENTS IN IMPREGNATING, WOOD WITH PRESERVATIVE AND COLOUR
ING MATERIALS, AND IN APPARATUS FOR THAT PURPOSE, to be as follows:
:,
I construct an air-tight vessel or chamber of cylindrical; rectangular, or
other form, in which the logs or pieces of wood are placed in a vertical
position. On the top of each log or piece is placed a plate of metal, or other
suitable material, with a ring or band of caoutchouc, or other flexible substance,
to connect it with the wood. The plates may be attached to the wood by nails
or screws, or otherwise, and they are kept in their proper positions by links,
connecting them to each other, and to rings or fixtures in the sides of the
chamber. There is a short tube in the centre of each plate, and these tubes are
connected by flexible tubes to other short tubes passing through the sides of the
[Price 8d 1

page_text: chamber. The chamber is closed by a cover, fixed by screws or otherwise, and
it has a cock in the cover or near the top for the escape of air, and another
cock for the admission of the preservative or coloring liquid; a third cock
serves for drawing off the liquid. The air cock being open the liquid is allowed
to flow in and fill the vessel; the air cock is then shut, and the operation
proceeds. The liquid penetrates into the wood at the lower end and partially at
the sides, and passes out at the upper end and through the flexible tubes and
into a gutter on the exterior of the chamber which conveys itaway. The liquid
penetrates with greater rapidity according to the pressure to which it is
subjected; it may be forced in by pumps or, it may descend from an elevated
reservoir, or it may be forced in by any other means. The wood is thus com-
pletely immersed in the liquid, which is enabled to penetrate it, owing to the
outlet afforded by the plate and flexible tube for the air or liquid contained in
the wood. I still farther fac ilitate the penetration of the liquid by connecting
an air pump, or a steam chamber, or other apparatus for producing a vacuum
or partial vacuum with the tubes which are in communication with the ends of
the logs or pieces of wood; I also reverse the action by causing the liquid to
enter the tubes leading to the ends of the pieces of wood, and I exhaust the air
from the chamber so that the liquid passes in the reverse direction through the
wood. By thus reversing or alternating the direction, the wood becomes very
the neces
uniformly and perfectly saturated. The apparatus is provided with the
sary cocks or valves for regulating the entrance and direction of the liquid, and
the action of the exhausting orvaccuumapparatus. The apparatus maybeplaced.
in a vertical position, or in a horizontal or inclined position if preferred. Thus,
for preparing railway sleepers and short pieces of timber, a vertical positionmay
be adopted, and the apparatus made of a height corresponding to the length of
the pieces. For masts and long pieces of timber a horizontal position may be
more convenient, and several short chambers may be united to form one long
chamber. In some cases the piece or pieces of wood may be screwed or
attached directly to the end or side of the chamber, which is then provided
with a tube or tubes, and serves in lieu of the detached plates and flexible
tubes. A long chamber may also be used for preparing short pieces of timber;
in which case, in lieu of employing a separate tube passing through the side or
wall of the chamber for each piece or log, I construct a flat hollow disc,
having the tubes fixed in each side of it, and having one larger tube or neck;
which is screwed or connected to a tube which passes through the side or top
of the chamber; or I employ in lieu of such disc a ring, or a straight or bent
main pipe,in which the small tubes are inserted, and which communicates with
the exterior of the chamber. In this way a long chamber may be filled with

page_text: several carriages full of short timber, each piece of which communicates with
the exterior of the chamber by means of the plates, flexible tubes, and hollow
discs or main pipes. When the number of pieces of wood to be prepared are
less than the number of small tubes, the superfluous tubes are closed by plugs
or cocks. The whole apparatus may be heated if required by a steam jacket, or
by a fire, or otherwise. The chambers may be made of metal, or of wood, or of
wood encased in metal or other suitable material, according to the nature of the
liquids to be employed in it. The wood should be clean and a thin slice may
be. cut off each end with a saw to expose the pores for the entrance and exit of
the liquid. The operation of the apparatus may be arrested when the liquid
escapes unchanged after passing through the wood: A portion of each of the
exit tubes inay be of glass, so that the colour of the escaping liquid may be
observed. The liquids employed may be creasote, solutions of tannin, tars, oils,
resins, fats, salts of calcium, sodium, aluminium, iron, zinc, mercury, or copper,
or other liquids or solutions. Solutions of indigo and other colouring matters
may be employed to colour the wood. Two solutions may be introduced in
succession, so as to decompose each other. in the pores of the wood.

page_text: I, the 'said,Charles Cowper, my executors or administrators, by an instrument
in writing under my, or their, or one of their hands and seals, should par
ticularly 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
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 Charles Cowper, do hereby declare the
nature of the said Invention, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement
thereof, that is to say :-
The Invention relates to improvements in that mode of impregnating wood
by which the preservative or colouring liquid or liquids is or are caused to
traverse the wood, by entering at one end or part, acd flowing out at the other
end, or another part of the same piece of wood.
: :
Various processes have been heretofore employed for impregnating wood
with preservative or colouring materials. Thus, the wood has been simply
immersed in the liquid contained in an open vessel. The wood has also been
placed in a close vessel, and the air has been exhausted, and the liquid has
then been introduced and forced in by pumps or otherwise. Another process
consists in inserting one end of the piece of wood in a water-tight bag or box
connected with an elevated cistern containing the liquid. By this last
arrangement, the liquid penetrates and percolates through the wood and drives
out the air before it, and finally passes out at the opposite end of the piece of
wood. This plan, however, involves considerabletrouble and labour in forming
the joint or connection with the end of the piece of wood, as the pressure of
the liquid has a tendency to open the joint and cause it to leak.
The present Invention relates to improvements in the method and apparatus
for applying the liquid so as to cause it to percolate through the wood. For
this purpose, the pieces of wood are completely inclosed within a close vessel,
and one end of each piece of wood is caused to communicate with the exterior
of the vessel, as herein-after described.
Figure 1 of the accompanying Drawing is an elevation of a close vessel,
provided with a cover, which can be secured by screws or otherwise; Figure 2,
is a section of the vessel without the cover; and Figure 3 is a section of the
vessel and cover, with the pieces of wood placed within the vessel. The same
letters refer to similar parts in each Figure.
A is the vessel or chamber, which may be inade of wood or metal, or of
wood inclosed in a metal case, or of any material sufficiently strong to resist
the
pressure to which it is to be exposed; and of a nature not to be injuriously

page_text: acted upon by the liquid to be employed; B is the cover, fixed by the screw
clamps, b, or in any other suitable manner; R' is a cock for the admission
of the liquid, and R is another cock for drawing off the liquid; R" is a cock
placed on the cover or at the upper part of the vessel, for the escape of the air
when the vessel is being filled with liquid; T, T, are a series of short tubes
passing through the side of the vessel. These tubes may be about half an
inch in diameter, or more or less, and may project about an inch and a
quarter, or more or less, into the interior of the vessel. Each of these tubes
can be closed by a plug applied to its interior or exterior, or by means of a
cock. A small gutter is formed at D, for the purpose of receiving the liquid,
which escapes at the tubes, and conducting it into a recipient or cistern. A
series of rings C, C, are firmly fixed to the interior of the chamber. d, d, are
loose plates, which are connected by flexible tubes e,e, to the short tubes T,T.
These plates are provided with rings or hooks, which receive the links f, f, by
which the plates are connected to each other, and to the rings C, C, in the side
of the vessel. The plates are thus kept in their places without being rigidly
fixed. Each plate d is connected to a piece of wood W, with the intervention
of a ring or cord of vulcanized caoutchouc or hemp, or other suitable material,
and the plate is kept in its place by nails or screws inserted into the wood.
Figure 4 is a section, on a larger scale, of one of the plates d, attached to a
piece of wood W. The plates d is perforated with a number of holes, through
which nails or spikes or screws p, p, may be passed. is the ring or cord, of
caoutchouc or other suitable material, which is laid upon the end of the piece
of wood W; the plate d is laid upon it, and nails or screws p, p, are driven
through it into the wood; the remaining holes are closed by plugs q, q.
Figure 5 is a section, and Figure 6 is a plan, of a plate d, having the spikes
P. p, attached to it; a ring or cord r, of caoutchouc or other suitable material,
of a size corresponding to the piece of wood W, is placed between the spikes,..
and the plate is then placed on the end of the piece of wood and struck with
a mallet so as to cause the spikes to enter the wood. These arrangements
of plates serve for pieces of wood of different diameters and shapes. The
mode of proceeding is as follows:-The pieces of wood W are cleansed from
adhering dirt, if necessary, and if the ends have not been recently cut,
a thin slice is removed by a saw from each end so as to expose the pores of
the wood. One of the plates dis then attached by screws or nails to one end
of each piece of wood, with the intervention of a ring or cord of vulcanized
caoutchouc or hemp, or other suitable material. The pieces of wood are then
placed in the chamber or vessel A, and the plates d are connected together
and to the sides of the chamber by the links f, f; a cord attached to a ring.

page_text: near the bottom of the vessel may also be wound round each piece of wood
to keep it in its place. The plates are then connected by the flexible tubes e,e,
to the short tubes T, Tand if there are more of the tubes. T, T, than the
number of pieces of wood; the remaining tubes T, T, are plugged up or closed
by their cocks. The cover B is then placed on the vessel and secured by the
screws b, b; the cock R is opened, and the cock Ris closed the cock-B
is opened, and the preservative or colouring liquid is allowed to flow in until
the vessel is full; the cock R is then closed. The reservoir which contains
the liquid is placed at a considerable height above the vessel A, or the liquid
is forced in by a pump or otherwise, so as to exert a considerable pressure
upon the wood in the vessel; this pressure acts upon the whole. of the
exterior of the wood, with the exception of the upper end which is placed in
connection with the exterior atmosphere by means of the plates and tubes
and T. The liquid is thus caused to infiltrate and percolate through the
pores of the wood from the lower end and partially from the sides, driving
out the air before it until it reaches the upper end, and flows out through.
the tubes e and T into the gutter D, which conveys it into a cistern: The
completion of the saturation of the wood may be ascertained by the liquid
passing out unchanged or of the full strength at which it enters. The links
ff, prevent, the pieces of wood from floating up to the top. of the vessel.
The vessel A may be heated by a steam jacket or otherwise during the
operation, if desired. When the operation is completed, the cock Ris
closed and the cock R is opened, the liquid, or a portion of it, is then run
out, through the cock R; the cover is then taken off, and the links and,
the flexible tubes are detached, and the pieces of wood are taken out and the
plates d removed from them. In lieu of forcing the liquid into the vessel by
pumps or a' column of liquid, it may be forced in by the pressure of the
atmosphere, by exhausting the air by means of an air pump or other appa
ratis connected to the tubes T; or both, or all of these..means; may be
employed simultaneously. In some cases it may be advantageous to pass the
liquid alternately in contrary directions through the wood. This is effected by
causing the liquid to enter at the pipes T, T, and to pass out at either of the.
cocks R, R, or R", which may be open to the atmosphere, or connected to a
pump or exhausting apparatus. In this arrangement, however, it is necessary.
to fix the plates d very firmly to the pieces of wood, to enable them to resist
the pressure of the liquid, which, then tends to force them off the wood, and.
if the pressure; be too great there is some danger of bursting or splitting the
wood. In conducting the operation as at first described, the pressure tends.
to keep the-plated in its place, and to keep the joint, tight, by.forcing it

page_text: against the wood, and as the pressure is applied to the exterior of the wood
there is no danger of splitting or bursting it.
The apparatus shewn in Figures 1, 2, and 3 may be conveniently employed
for saturating railway sleepers and similar pieces of wood. The apparatus may
be placed in a horizontal or inclined position if more convenient.
Thus, Figure 7 is a longitudinal section ofa long horizontal chamber, which
may be employed for saturating or impregnating railway sleepers and short
pieces of wood, and also for impregnating masts and long pieces of timber.
A is the chamber, and B is the cover; J, J, are hollow discs, or flat, circular,
water-tight boxes, formed of two plates of metal or wood, or other suitable
inaterial, united at their edges, and by intermediate stays, if necessary, and
having a number of short tubes projecting from each side. At one part of the
periphery of the box is a short neck or tube V, which is connected by a union
joint or flanges, or otherwise, to an aperture in the chamber A, which is
furnished with a cock S on the exterior:
1:
Figure 8 is a front view, and Figure 9 is a transverse section of one of
the boxes J; they are of smaller diameter than the chamber A, so as to
allow space for a man to get past them. The sleepers, or short pieces of
timber W, have plates with flexible tubes attached to them as before, and
they are placed upon trucks K, K, and one of these trucks is run into the
'chamber, taking care that all the flexible tubes are directed towards the
mouth or front of the chamber; oue of the boxes J is then fitted into its
place, and the flexible tubes are connected to the short tubes on one side
of the box. The flexible tubes may be about two feet long, so as to enable
the workman to connect them with facility; another loaded truck is then run
into the chamber, with its flexible tubes directed towards the back of the
chamber, and they are similarly connected to the other side of the box J;
a third truck is introduced with the flexible tubes directed towards the mouth
of the chamber, and another box J is then introduced, and so on, until the
chamber is filled. The timber is fastened by ropes or otherwise on the trucks,
which are kept in their places by struts or bars k, k, so as to prevent the wood
from floating up or being displaced by the liquid; the cover B is then secured
to the mouth of the chamber, and the liquid is admitted through a pipe and
cock R' while the air escapes at a cock R"; when the vessel is full of liquid
the cock R is closed, and the liquid is forced in by pumps or otherwise. The
liquid percolates through the wood until it escapes through the boxes J, J, and
cocks S, S, which are kept open during the operation; when the timber is
sufficiently impregnated, the cock R' is closed, and the cocks R and R" are
opened, and the liquid is drawn off from the chamber; the cover B is then

page_text: removed, and the trucks K are drawn out, and the boxes J.removed
; the
chamber is then charged again with a fresh lot of timber, and so, on. The
chamber has apertures at intervals to allow of the boxes J, J, being fixed in
different, positions, according to the lengths of timber to be impregnated, and
the apertures, which are not in use are closed by plugs or cocks. By the ap
plication of the collecting boxes J,J,a comparatively small number of apertures
suffice; whereas if a set of short tubes were fixed in the sides of the chamber
for each different length of timber, the sides of the chamber would be weakened,
and the tubes would be more exposed to injury in introducing the timber,
besides the inconvenience of having to plug up the multitude of tubes which
would be out of use; the apparatus may, however, be so constructed, if
preferred. In lieu of the collecting boxes J, collecting vessels of other forms
may be employed.
Thus, Figure 10 represents a collecting tube J, closed at one end and open
at the other end V, which is to be connected to one of the apertures in the
chamber shewn in Figure 7; this tube J is furnished with a series of short
tubes, to which the flexible tubes are to be connected as before:
Figure 11 shows a similar arrangement to Figure 10, except that the col-
lecting tube J is straight instead of curved. In lieu of connecting the
collecting tubes or vessels to apertures in the chamber, they may be connected
to one general collecting tube or main pipe, placed within the chamber, and
communicating with the exterior by a single aperture. When very long pieces
of timber are to be impregnated, only one collecting vessel or tube is required,
which is placed near the mouth of the chamber. In some cases, particularly
when operating upon single pieces, or a few pieces of wood, the wood may be
connected directly to the end or side of the chamber by means of screws or
other wise, with the intervention of a ring of packing between the wood and the
end or side of the chamber; an aperture is made in the end of the chamber
within the ring of packing, through which aperture the air escapes and is
followed by the liquid, which percolates through the wood; the end or side
of the chamber then acts in a similar manner to the plates d, d, in Figures
3, 4, 5, and 6. The apparatus shewn in Figures 1, 2, and 3 may be made
with a moveable bottom, secured by bolts and nuts or otherwise; and when
required the bottom may be removed, and several of such vessels or chambers
may be bolted or fixed together, so as to make one long chamber.
Figure 12 is a plan of a vessel constructed in a similar manner to that
shewn in Figures 1, 2, and 3; Figure 13 is a side view or elevation of the
These Figures show e methodofennlrings vacuum szavhaustin

page_text: to effect or assist in effecting the impregnation of the wood. The short tubes
T, T, are connected to a collecting tube Y, either directly or through short
pieces of glass tube, by means of which the colour of the liquid passing through
them may be seen, The tube Y is prolonged at a, and connected with any
suitable exhausting apparatus. Thus it may be connected through a cock Q
with a chamber (. A cock on the top of the chamber O is opened, and steam
is admitted through another pipe and cock from a boiler; the air is thus
driven out of the chamber O, and the cocks are then closed; the steam then
condenses or is condensed by a jet of water introduced into the chamber or
applied to its exterior. A partial vacuum is thus produced in the chamber O;
the cock Q is then opened, and the pressure of the atmosphere is thus
partially removed from the upper ends of the pieces of wood, and the liquid is
thus caused to percolate through the wood. The pipe Y is connected by the
cock N to the pipe H, which is also connected by the cock R' to the chamber
A; this pipe H serves for the introduction of the liquid. R is a cock for
drawing off the liquid from the chamber A; P is a pipe which connects the
chamber A with the vacuum chamber O, or directly to the steam boiler; it is
provided with a cock X. The mode of proceeding is as follows:-All the
cocks are closed, and the wood is introduced into the chamber A, and connected
by the flexible tubes to the tubes T, T, in the manner herein-before described;
the cover,
B is secured in its place; the cocks R' and R" are opened, and the
chamber A is filled with the liquid; the cock R" is then closed, and the cock
Qis opened; a partial vacuum having been previously made in the chamber O,
the liquid now percolates and ascends through the wood, driving the air into
the vacuum chamber O. The process of forming the vacuum in the chamber
O may be repeated from time to time as the air or liquid accumulates in it.
After passing the liquid through the wood in this direction for some time its
direction may be reversed, and it may be caused to descend through the wood
in the following manner-The cocks X, Q, R', are closed, and R and R" are
opened to allow the liquid to flow out of the chamber A; the cocks R and R"
are then closed and N is opened; the cock X is then opened so as to connect
the chamber A with the vacuum chamber O, and the operation proceeds. Or
if the vacuum is to be made by the direct application of steam to the chamber
A, after drawing off the liquid the cock is closed aud R" is left open; steam
is then admitted by the cock X until the air is driven out at: R", and both
those cocks are then closed. A jet of the liquid is then introduced at R¹, or a
jet of water or other liquid may be introduced through another cock provided
for the purpose; the steam is thus condensed, and the cock is immediately

page_text: closed again; the operation then goes on, and the liquid descends through
the wood. This alternate reversal of the direction of the current may be
repeated as often as desired. As already mentioned, it is necessary when
introducing the liquid at the end of the wood to which the plate is connected
to fix the plate very securely to the wood, as it has to resist the pressure tend-
ing to force it away from the wood. This is not necessary when the liquid is
introduced from the chamber and escapes from the end of the wood to which
the plate is connected. As regards the liquids to be employed, they may be
creasote, tar, oils, and resins, fatty matters, tannin, salts of lime, soda, alumina,
iron, zinc, mercury, copper, or other preservative materials reduced to the
liquid state by heat, or by dissolving them in water or other suitable solvent.
Solutions of indigo, and other colouring materials, may be employed to color
the wood. Two different solutions or liquids may be introduced in succession.
Thus, a solution of sulphate or nitrate of iron may be introduced, and a
solution of prussiate of potash may afterwards be introduced, so as to form a
precipitate of prussian blue in the pores of the wood. The present Invention,
bowever, does not relate to the nature of the liquids employed, but to the
apparatus and mode of impregnating the wood with liquids.
Having now described the nature of the said Invention and in what manner
the same is to be performed, I wish it to be understood that I do not claim'
generally the impregnating wood by causing the liquid to enter it at one end
and to pass out at the other end, such process having been known for many
years; but what I claim is,-
First, the mode of impregnating wood with preservative or colouring
materials, by completely inclosing it in a vessel into which the preservative or
colouring liquid is introduced, and connecting one end of the piece of wood by
means of a plate with the exterior of the vessel, and causing the liquid in the
vessel to be pressed upon with a greater pressure than that to which the afore-
said end of the piece of wood is exposed, by which means the liquid is caused
to percolate through the wood, and at the same time to press the end of the
piece of wood against the aforesaid plate, as herein-before described.
Secondly, the impregnating wood with preservative or colouring materials by
completely inclosing it in a close vessel, and connecting a plate to one end of
the piece of wood, as herein-before described, and then passing the preservative
or colouring liquid through the wood in both directions, successively or alter-
nately, as herein-before described.
Third, I claim the apparatus for impregnating wood, consisting of the
combination of the plates d and their flexible tubes, with a close vessel, having

page_text: suitable connections for the same, as herein-before described in reference to
Figures 1, 2, and 3.
Fourth, I claim the combination of apparatus for impregnating wood,
herein-before described in reference to Figure 7.
Fifth, I claim the combination of apparatus for impregnating wood, herein-
before described in reference to Figures 12 and 13.
In witness whereof, I, the said Charles Cowper, have hereunto set my
hand and seal, this Twenty-ninth day of July, in the year of our Lord
One thousand eight hundred and fifty-six.
Witness,
THO TAYLOR, Jr.,
7, Wellington Row,
Bethnal Green.
CHARLES COWPER. (L.S.)