IM- PROVEMENTS IN THE MANUFACTURE OF PULP FOR MAKING PAPER OR PAPIER MACHÉ. AND IN THE APPARATUS EMPLOYED THEREIN
Year: 1870

page_text: LETTERS PATENT to William Law, of Kilbagie, in the County of
Clackmannan, North Britain, Overseer, for the Invention of "IM-
PROVEMENTS IN THE MANUFACTURE OF PULP FOR MAKING PAPER OR PAPIER
MACHÉ. AND IN THE APPARATUS EMPLOYED THEREIN."
Sealed the 6th September 1870, and dated the 7th March 1870.
PROVISIONAL SPECIFICATION left by the said William Law at the
Office of the Commissioners of Patents, with his Petition, on the
7th March 1870.
I, WILLIAM LAW, of Kilbagie, in the County of Clackmannan, North
Britain, Overseer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN THE MANUFACTURE OF PULP FOR MAKING PAPER OR
PAPIER-MACHÉ, AND IN THE APPARATUS EMPLOYED THEREIN," to be as follows:-
:-
My Invention consists in an improved mode or method of reducing
woody or other fibres to a pulp suitable for the manufacture of paper or
papier maché. This I accomplish by reducing wood mechanically, first
into small pieces, shavings, or sawdust; I then place a sufficient

page_text: Mammuy of either O
A strong boners or wigesters,
in which is a solution of caustic soda. I boil or digest these for about
four hours under a pressure of about two hundred pounds per square
inch.
My improved boiler or digester in which the boiling or digesting is
performed I make (if a single one) with an inner and outer shell. The
inner has two mouth picces (if placed vertical), one of them at the top
and the other at the bottom or lower end. The upper one is for charging
the same with materials, and the lower one is for discharging. These
month picces have strong plugs or lids screwed into them or bolted on,
and made steam-tight. After the inner case is charged with the
necessary materials and the lids or plugs made tight superheated steam
or heated air, or both, is or are allowed to play in the space between the
inner and outer shell, so as to raise the pressure in the inner one (in
which the materials are) to about the before-mentioned pressure, viz.,
two hundred pounds per square inch. The steam is superheated in a set
of pipes cither in coils or in a series of hollow circular rings connected
together above each other, having inlet and outlet pipes connected to
them. The inlet pipe leads from a steam boiler to the furnace coil, and
the outlet pipe leads from the coil or circular pipes to the space between
the inner and outer shells. The outer shell is set in brickwork, and
has a winding flue round it from bottom to top, through which the
products of combustion from the steam superheating furnace (which is
placed below the coil or hollow circular rings) pass, and thus heats the
exterior of the outer shell, and prevents the loss of heat from its interior.
They then pass onward to the chimney. I sometimes place more than
one interior boiler or digester in one outer shell. I generally place four
in one shell, each having its inlet and outlet mouth pieces, and also
proper pipes attached to their bottoms or lowest points for running off
the liquor (in which the fibrous materials have been boiled or digested).
.I sometimes make the inner shell of my boiler or digester perforated, and
place a coil of pipes charged with superheated steam between the shells.
The heat from these coils boils the liquor, while the inner perforated
hell provents the materials from touching the coil of pipes. In this
case the inner shell may be made of light metal plates. I sometimes
also make a boiler or digester similar to the above, but with another
-hell on the outside of the two above-mentioned shells, and having a.
nitable space between them. Within that space I allow the heated air

page_text: to circulate freely, while superheated steam is allowed to play in the
inside of the coil of pipes round which the liquor (which passes through
the perforated shell) flows; or I reverse the process by passing hot air
through the coil of pipes, and making superheated steam play in the
space between the shells, and as before a winding flue is formed round
the outer shell, through which flue the products of combustion flow from
the steam or air superheater to the chimney. Instead of placing these
boilers or digesters vertically I sometimes place or fix some of them
horizontally, and build them in, on, and over a fluc. In this case the
air superheating pipes and passages are enclosed in a furnace at or near
one end of the boiler or digester. After the products of combustion
leave this furnace they pass through an opening in the brickwork, and
from thence to the further end of the boiler or digester, and then return
along the sides to near the superheating furnace, where they escape
through a flue to the chimney. If air is to be superheated for the
purpose of boiling, a proper fan is made use of to force the air through
the superheating pipes and aparatus. The air from the fan enters the
heaters, which I prefer to be of a semicircular or horse-shoe shape, the
lower ends of the legs of which are jointed into suitable hollow sockets
for returning the air over and over the heated furnace repeatedly until it
is sufficiently heated. The further end (from the furnace) of this boiler
or digester projects through the brickwork or seating, to which end the
charging and discharging mouth piece is fixed. The liquor charging
mouth piece is attached to the boiler about its centre, and projects
upwards through the top brickwork. These mouth pieces are also
Near to
fitted with screwed plugs, lids, or covers, as before described.
the discharging end a pressure gauge and thermometer are attached.
On the top of the furnace brickwork or other suitable place I mount a
small vessel, say, similar in shape to an egg-ended boiler. This auxiliary
vessel is also charged with liquor, and is connected to one or more or to
all of the boilers or digesters by means of two pipes to each, one of
which pipes is attached to the upper sides of both vessel and digester,
and is for allowing the steam or vapour to enter the small vessel from
the boiler or digester. The other pipe is connected to the under side of
the small vessel and to the top of the boiler or digester, but entering it
for some distance. This allows the liquor to flow from the upper or
small vessel into the lower to make up for any leakage or deficiency.
On each pipe a stop-cock is mounted to shut off or regulate the flow of
liquor or vapour through them. A pipe is also attached to the under

page_text: side of the boiler or digester fitted with a suitable cock for running off
the liquor in which the materials have been boiled or digested. A
suitable mouth piece is attached to the upper side of the small vessel
for charging it with liquor. After the liquor has been run off from the
boiler, boilers, or digesters the pulp material or materials under operation
is or are placed in and submitted to the action of a washing engine a
sufficient time, and from that it or they are worked in a poaching engine
containing a solution of chloride of lime or bleaching powder. I also
add a little sulphuric acid if necessary. After being in the poaching
engine a suitable time the whole material or materials along with the
bleaching liquor are run off into stone chests with false bottoms for
draining off the liquor. The pulp material or materials can then be
put through the ordinary process and prepared for the manufacture of
paper or papier maché. I put wood, wood shavings, or sawdust through
the same process. When I make use of esparto grass for making pulp I
cut the coarsest of it into lengths of about three inches, either by hand
or by means of an ordinary straw cutter, before putting it in the boiler,
boilers, or digesters. By the before-mentioned processes I effect a great
saving in time and materials.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Law in the Great Seal Patent Office
on the 7th September 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
Law, of Kilbagie, in the County of Clackmannan, North Britain,
Overseer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventh day of March, in the year of
our Lord One thousand eight hundred and seventy, in the thirty-third
year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said William Law, Her special licence that I,
the said William Law, my executors, administrators, and assigns, or
such others as I, the said William Law, my executors, administrators,
and assigns, should at 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,

page_text: and Isle of Man, an Invention for "IMPROVEMENTS IN THE Manufacture
OF PULP FOR MAKING PAPER OR PAPIER MACHÉ, AND IN THE APPARATUS EMPLOYED
THEREIN," upon the condition (amongst others) that I, the said William
Law, 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 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 Law, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by
the following statement, reference being had to the Drawings hereunto
annexed, that is to say:
-
My Invention consists in an improved mode or method of reducing
woody or other fibres to a pulp suitable for the manufacture of paper or
papier mache. This I accomplish by reducing wood mechanically, first
into small pieces, shavings, or sawdust; I then place a sufficient quantity
of either of these into one or more strong boilers or digesters in which is
a solution of caustic soda. I boil or digest these for about four hours
under a pressure of about two hundred pounds per square inch.
. My improved boiler or digester in which the boiling or digesting is
performed I make (if a single one) with an inner and outer shell. The
inner has two mouth pieces (if placed vertical), one of them at the top
and the other at the bottom or lower end. The upper one is for charging
the same with materials and the lower one is for discharging. These
mouth pieces have strong plugs or lids screwed into them and made
steam-tight. After the inner caso is charged with the necessary materials
and the lids or plugs made tight superheated steam or heated air, or
both, is or are allowed to play in the space between the inner and outer
shells so as to raise the pressure in the inner one (in which the materials
are) to about the before-mentioned pressure, viz., two hundred pounds
per square inch. The steam is superheated in a set of pipes either in
coils or in a series of hollow circular rings connected together above each
other, having inlet and outlet pipes connected to them. The inlet pipe
leads from a steam boiler to the furnace coil, and the outlet pipe leads.
from the coil or circular pipes to the space between the inner and outer
shells. The outer shell is set in brickwork, and has a winding fluc round

page_text: it from bottom to top through which the products of combustion from
the steam superheating furnace (which is placed below the coil or hollow
circular rings) pass, and thus heats the exterior of the outer shell and
prevents the loss of heat from its interior; they then pass onward to the
chimney. I sometimes place more than one interior boiler or digester
in one outer shell. I generally place four in one shell, each having its
inlet and outlet mouth pieces, and also proper pipes attached to their
bottoms or lowest points for running off the liquor (in which the fibrous
materials have been boiled or digested) into proper evaporating pans.
I sometimes make the inner shell of my boiler or digester perforated,
and place a coil of pipes charged with superheated steam between the
shells. The heat from these coils boils the liquor, while the inner per-
forated shell prevents the materials from touching the coil of pipes.
In this case the inner shell may be made of light metal plates. I
sometimes also make a boiler or digester similar to the above but with
another shell outside of the two above-mentioned shells, and having a
suitable space between them. Within that space I allow the heated air
to circulate freely, while superheated steam is allowed to play in the
inside of the coil of pipes round which the liquor (which passes through
the perforated shell) flows. Or I reverse the process by passing hot air
through the coil of pipes, and making superheated steam play in the
space between the shells, and as before a winding flue is formed round
the outer shell, through which flue the products of combustion flow from
the steam or air superheater to the chimney. Instead of placing these
boilers or digesters vertically I sometimes place or fix some of them
horizontally, and build them in, on, and over a flue. In this case the
air superheating pipes and passages are enclosed in a furnace at or near
one end of the boiler or digester. After the products of combustion
leave this furnace they pass through an opening in the brickwork, and
from thence to the further end of the boiler or digester, and then return
along the sides to near the superheating furnace, where they escape
through a flue to the chimney. If air is to be superheated for the
purpose of boiling in the first process, or for evaporating the water from
the liquor in a pan, a proper fan is made use of to force the air through
the superheating pipes and apparatus. The air from the fan enters the
heaters, which I prefer to be of a semicircular or horse-shoe shape, the
lower ends of the legs of which are jointed into suitable hollow sockets
for returning the air over and over the heated furnace repeatedly untill
it is sufficiently heated. The further end (from the furnace) of this

page_text: effect I will now proceed to describe the same more fully and with
reference to the Drawings hereunto annexed.
Figure 1, Sheet I., is a sectional elevation of a single boiler or digester
according to my Invention, and Figure 2 is a sectional plan of the same.
A is the inner shell, and B is the outer one. Similar letters refer to
similar parts. In these Figures I have shewn this boiler or digester as
standing upright or vertical. The shells A and B are firmly rivetted or
otherwise secured to the top plate C, and to this again is secured the
strong mouth piece D through its broad and strong flange E, or the top
plate C may be dispensed with, and the mouth piece D fastened direct
to the angle irons a, a, a, a, or flanges of the shells A and B. F is a
strong plug or lid, which has its flanges 6 faced true, and has a strong
screw thread cut, cast, or otherwise formed on the exterior of the plug
portion c. This screw takes into an internal screw cut, cast, or similarly
formed in the upper portion & of the mouth piece D, which also has its 1
flange e faced true, so as to form a joint with the flange 6 of the plug or
lid F, when it is screwed in firm by means of a lever or key having an
end properly formed so as to lay hold of or catch the projecting portion f
of the plug F, which may be formed square in section or of any other
suitable form. A pin g is secured in the end of this portion, on which
is mounted a swivel ring g³, so that the plug F may be laid hold of and
borne up by any suitable tackle, and so leave the plug at liberty to be
turned round either way when it is being screwed in or out of the
mouth piece D. This upper mouth piece is for charging the boiler with
the proper material for making pulp as well as the proper liquor and ?
chemicals. A similar mouth piece D is attached horizontally at or near
the bottom of the boiler or digester. F is the plug, cover, or lid. The
mouth piece D¹ is shewn as fitted to a piece D³, which passes through
the brickwork and is attached to the outer and inner shells by fixings
through them and the flanges of the piece D³. D' is a strong casting,
which serves as a bottom to both shells, and to which they are securely
fixed. This piece may be cast in one with the piece D³. The centre of
this casting has a boss and hole in it to which a pipe E' is fixed. This
pipe has a suitable stop-cock mounted on it but not shewn in the
Drawings, so that the liquor can be run off at pleasure. The lid or a
plug F has a strap or collar / mounted loosely in a groove formed in its
flange. A ring h³ is attached to this strap or collar, and to which ring

page_text: boiler or digester projects through the brickwork or seating, to which
end the charging and discharging mouth piece is fixed. The liquor
charging mouth piece is attached to the boiler about its centre, and pro-
jects upwards through the top brickwork. These mouth pieces are also
fitted with screwed plugs, lids, or covers, as before described. Near to
the discharging end a pressure gauge and thermometer are attached. On
the top of the furnace brickwork or other suitable place I mount a small
vessel, say, similar in shape to an egg-ended boiler. This auxiliary vessel
is also charged with liquor, and is connected to one or more or to all of
the boilers or digesters by means of two pipes to each, one of which
pipes is attached to the upper sides of both vessel and digester, and is
for allowing the steam or vapour to enter the small vessel from the boiler
or digester. The other pipe is connected to the under side of the small
vessel and to the top of the boiler or digester, but entering it for some
distance. This allows the liquor to flow from the upper or small vessel
into the lower to make up for any leakage or deficiency. On each pipe
a stop-cock is mounted to shut off or regulate the flow of liquor or
vapour through them. A pipe is also attached to the under side of the
boiler or digester fitted with a suitable cock for running off the liquor in
which the materials have been boiled or digested. A suitable mouth
piece is attached to the upper side of the small vessel for charging it
with liquor. After the liquor has been run off from the boiler, boilers,
or digesters the pulp material or materials under operation is or are
placed in and submitted to the action of a washing engine a sufficient
time, and from that it or they are worked in a poaching engine con-
taining a solution of chloride of lime or bleaching powder. I also add
a little sulphuric acid if necessary. After being in the poaching engine
a suitable time the whole material or materials along with the bleaching
liquor are run off into stone chests with false bottoms for draining off
the liquor. The pulp material or materials can then be put through
the ordinary process and prepared for the manufacture of paper or papier
mache. I put wood, wood shavings, or sawdust through the same process.
When I make use of esparto grass for making pulp I cut the coarsest
of it into lengths of about three inches, cither by hand or by means of
an ordinary straw cutter, before putting it in the boiler, boilers, or
digesters. By the before-mentioned processes I effect a great saving in
time and materials.
In order to shew clearly the manner in which I carry the same into

page_text: the lifting tackle may be applied. The plug or lid turns round in the
strap or collar while it is being screwed or unscrewed by means of a key
or lever applied to the projecting piece. This lower mouth piece is
for discharging the materials from the boiler or digester after they have
been sufficiently operated on. D³ is a pipe for conducting steam, super-
heated steam, or hot air, either all or singly, into the space between the
inner and outer shells. A pipe i is fixed to the bottom of the boiler or
digester, and leads into the space between the inner and outer shells for
letting off any condensed steam or water which may be therein and to
keep up a current. These pipes are also furnished with suitable stop-
cocks. The boiler or digester rests on a casting E³, which is set on a
piece of hollow brickwork E. This brickwork extends upwards round
the digester, but at a distance so far apart from it as will be sufficient to
get a winding or helical flue formed therein. Es is the flue, which is
made to wind helically round the outer shell B by means of the brick-
work, the inner end of which is supported on brackets or angle iron ≫
secured to the outer shell B. F' is an opening or inlet through which
the products of combustion from a furnace pass into the interior of the
brickwork, and from thence through a hole F³ in the casting E³ upward
through the helical or winding flue E' untill they arrive at the top,
where they pass into one or more flues, as Es, which is or are formed in
the brickwork, whence they pass downward and are led off by a flue to
a proper chimney.
In the foregoing I have only described a single boiler or digester with
outer shell set in brickwork, but before describing the mode of working
or operating with the same I will now describe a modification of my
Invention and the means made use of for producing and supplying hot
air, superheated steam, or steam to the boiler or digester or boilers or
digesters. The same letters of reference made use of while describing
Figures 1 and 2, Sheet I., will serve as far as they go to similar parts
while describing Figures 3 and 4, Sheet II. In this modification I
mount any suitable number of boilers or digesters in one outer shell.
In Figure 3 I have shewn a sectional elevation, and in Figure 4.a plan
of a set of four boilers or digesters so mounted, and with suitable steam
superheating, or air heating apparatus attached. As before, A, A, A, A,
are the inner, and B the outer shells; C is the top plate; D, D, D, D, arc
the mouth pieces; E, E, E, E, are their flanges; a, a, are the angle iron
or flanges of the shell A; F, F, F, F, are the strong plugs or lids, which

page_text: are screwed into the mouth pieces D, D, D, D; ƒ are the projecting
portion of the plugs F for laying hold of with a key or lever to screw
them in and out with; g is the pin on which the swivel ring is
mounted, to which tackle can be attached for lifting and suspending the
plugs F, F, F, F, by; D¹, D', D', D', are the month pieces attached
horizontally near the bottoms; F¹, F', F', F', are the plugs or lids; E' is
the hollow brickwork on and in which the combined boilers or digesters
are set; E, E³, is the winding flue; i, i, i, are the brickwork partitions
which divide the space and form a flue; the inner ends of the brickwork
rest on the brackets or angle iron **. E' is the descending flue, which
goes down to a flue which leads off to the chimney; F² is the opening or
inlet through which the products of combustion pass from an air heating
or steam superheating furnace G, the bars of which are seen in dotted
lines in the plan. The steam is supplied from a boiler through the
pipe E, which is furnished with a stop-cock H₁; it then passes into the
circular hollow castings or they may be coils H³, H³, H*, H³, H®, H², in
succession, where it is heated by the furnace G; it then makes its exit
from there by the pipe I, and passes into the space within the outer
shell B, where it circulates round and heats the inner shells, boilers, or
digesters A. with their contents. The products of combustion pass from:
the furnace G along the flue G' (in which the superheated steam pipe I
is fixed) and into the hollow brick building, then in through the helical
or winding flue E', around the outer shell A. to the top, when it then
descends through the flue or flues E* formed in the brickwork (shewn in
this case in dotted lines), and onwards through the flue E' to the proper 1
chimney J. J and J' are dampers for regulating the draught of the
furnace G, or for letting or causing the products of combustion to pass.
either way as may be desired. To the under side of the bottom plate of
the outer shell B I fix a suitable pipe K for running off any condensed
stcam or water. This pipe K is shewn in dotted lines, and is furnished 3
with a suitable stop-cock K². This pipe may either discharge by itself
or run into a branched pipe K². One of the branches K³ may be made to
proceed from a similar set of boilers or digesters, and discharge their
condensed steam or water through the same leading pipe K*. Suitable
liquor discharging pipes E³, E³, E³, E³, are fixed to the lower ends of the
inner shells. These lead to suitable stop-cocks L, L, L, L, which have
their opposite ends attached to branches of a leading main pipe L³, which
may be led so as to discharge the liquor into proper evaporating pans or
to any other convenient receptacle.

page_text: The mode of operation is as follows:-I place a sufficient quantity of
the fibrous materials that are to be reduced to pulp into one or other
or all of the before-described vessels, boilers, or digesters, in which is a
solution of caustic soda. I then screw fast the lid, cover, or plug F into
its seat in the mouth piece D, the lower plug having been previously
made fast. Superheated steam or air, or both, is or are allowed to play
between the inner and outer shells, while the products of combustion arc
allowed to pass from the superheating furnace G into the fluc, which
winds helically round the outer shell, and so imparts or gives out some
of its heat to the shell, which assists to keep up the heat of the super-
heated steam or air within it; they then pass onwards to the chimney:
By these means I raise the pressure in the inner shell to about two
hundred pounds per square inch. I boil or digest the materials for
about four hours under that pressure. After the liquor has been run off
from the boiler or digester the lower plug or lid is unscrewed, and the
pulp material or materials under operation is or are placed in and
submitted to the action of a washing engine a sufficient time, and from
that to a poaching engine containing a solution of chloride of lime or
bleaching powder, with a little sulphuric acid added to it if necessary.
After being in the poaching engine a suitable time the whole is then
run off into stone troughs or chests with false bottoms for draining off
the liquor. The pulp material or materials can then be put through
the ordinary process and prepared for the manufacture of paper or papier
mache.
I sometimes make the inner shell A of my boilers or digesters of
perforated metal, as shewn in Figures 5 and 6. Figure 5 is a sectional
clevation, and Figure 6 is a plan of the same, Sheet I. B, as before, is
the outer shell, which in this case has to resist the great pressure
required. A coil of pipes ; winds round between the inner and outer
shells, through which superheated steam or hot air is allowed to play.
The liquor passes freely through the perforated inner shell and comes in
contact with the coil of pipes ; and the inside of the outer shell, and
gets heated to the proper degree. This modification is in every other
respect similar to that represented in Figures 1 and 2 in Sheet I., and
need not be further described. The chief use of the perforated inner
shell is to keep the material from becoming entangled with the coil of
pipes j. I sometimes also mount these in sets of two, three, four, or
any other suitable number, as has already been described with reference

page_text: to Figures 3 and 4. I sometimes also make a boiler or digester similar
to Figures 5 and 6, Sheet I., but with another shell on the outside of
the shell B, and having a suitable space between them. Within that
space I allow the heated air to circulate freely, while superheated steam
is allowed to play in the inside of the coil of pipes round which the
liquor flows. I sometimes reverse the process and pass the hot air
through the coil of pipes, and make the superheated steam play in the
space between the two outer shells, and as before a winding flue is
formed round the outer shell, through which the products of combustion
flow, as has already been described with reference to Figures 1 and 2,
Sheet 1, and in Figures 3 and 4, Sheet II. Instead of placing theso
boilers or digesters vertically I sometimes place them horizontally, and
build them in, on, and over a flue.
1
In Sheet I. Figure 7 is a sectional elevation; Figure 8 is a sectional
plan through the dotted lines k, k, of Figure 7; Figure 9 is a cross 1
sectional clevation through the dotted lines 1, 2, in Figure 7; and
Figure 10 is another sectional elevation through m, m, of the sanie
Figure. In this case I dispense with the exterior shell, and place the
boiler or digester proper in direct contact with the flame and gases.
A is the boiler or digester laid horizontally in the brick setting M. One 2
end of this boiler or digester is globular and is set nearest to the
furnace N. The other end is furnished with the before-described
charging and discharging mouth piece D' and lid or plug F¹, which
project through the brickwork. At or near this end the pressure gauge n
is mounted. A thermometer o may be mounted near the egg end. The 2
liquor charging mouth piece D in this case is fixed on the top or upper
part of the boiler or digester, and projects upwards through the flue and
brickwork, and is also fitted with a plug, lid, or cover F screwed in
the mouth piece D. O is a vessel similar to an egg-ended steam boiler
mounted on two brackets placed on or near the top of the furnace 3
building. This vessel also has a mouth piece P with screwed plug, lid,
or cover P¹ for charging the same with liquor. This vessel is connected
to the boiler or digester A by a pipe p, which is attached to the under
part of the vessel O and to the boiler A. The end of this pipo dips into
the boiler for some distance, as shewn in dotted lines, to make sure that a
the pipe end will always be closed by the liquid therein. The other
pipe is attached to the upper parts of both vessel O and boiler, and
both pipes have stop-cocks ", ³, fixed on them. When the boiler or

page_text: r
digester is in operation the vessel O is used as a liquor compensating
reservoir for making up any scarcity or deficiency in the boiler through
leakage or otherwise. When compensation is to be made the stop-
cock' is opened on the pipe through which the liquor is to flow, the
other is then opened, which allows the steam or vapour to pass from
the upper part of the boiler A to the upper part of the vessel O, which
puts the pressure in each in or near an equilibrium, when the liquor by
its gravity descends to the lower vessel, boiler, or digester A. In this
case I sometimes place a heating coil of pipes ; similar to that already
described with reference to Figures 5 and 6. A suitable waste pipe & is
fixed to the under side of the shell B. N is the furnace, in which are
fitted and built the curved semicircular or horse-shoe pipes Q, Q, which
are heated by it. The lower ends of these pipes are jointed and fastened
in sockets or facets in the curved castings R, R. S is a fan (which may
be driven in any convenient manner from any prime mover) for forcing
air through the pipe S¹ into the curved pipes Q, Q, where it passes and
repasses over the furnace untill it becomes heated to the necessary
degree, when it is then led off by the pipe T to heat one or more of the
before-described boilers or digesters constructed according to any one or
all of the different modifications of boilers or digesters. To all of the
boilers or digesters I mount suitable pressure gauges n and thermo-
meter o, indicated by dotted lines in the Drawings. The spaces in or
around the digesters or boilers in which steam, superheated steam, hot
air, or one or other or all of them are allowed to play have pipes in
communication with them and proper stop-cocks mounted on them, so
that a constant current of either can be kept up and regulated when
desired. The coil of pipes ; in Figures 5 and 6, Sheet I., is also furnished
with an inlet and outlet regulating stop-cocks. Although I have shewn
the plugs, lids, or covers to be screwed into the charging and discharging
mouth pieces of the boilers or digesters, I also have holes formed in
their flanges to suit holes formed in the flanges of the mouth pieces, so
that bolts can be inserted therein, and the lids, plugs, or covers be made
fast by them, after the screws formed on them and in the mouth pieces
have been rendered useless.
And having now described the nature of my said Invention, and in
what manner the same is to be performed, I declare that I claim,-
First. The construction of boilers or digesters for pulp making with
an inner and outer shell, and causing steam, superheated steam, or hot

page_text: air to circulate between these shells, and with a helical flue winding
round the outer shell to heat the same, as described and set forth in the
Drawings hereunto annexed.
Second. The mounting of more than one boiler or digester in one
outer shell, as described with reference to the Drawings.
Third. The placing of a heating coil of pipes in a pulp-making boiler
or digester between an inner perforated shell and an outer solid shell, as
has been described with reference to the Drawings hereunto annexed.
Fourth. The mounting of pulp-making single shelled boiler or boilers,
digester or digesters in such a manner in, on, or over a flue in which
the products of combustion act to heat the same after they have passed
from the steam superheating or air heating furnace, as described and
represented in the Drawings hereunto annexed.
Fifth. The combination of the various improvements relating to the
making and mounting of pulp-making boilers or digesters, as herein-
before described and represented in the Drawings hereunto annexed.
Sixth. The reducing of the various pulp-making materials by dissolving
the resinous and siliceous portions of the same by means of my improved
apparatus, so as to convert these materials into a pulp suitable for the
manufacture of paper or papier mache.
.
In witness whereof, I, the said William Law, have hereunto set
my hand and seal, this Fifth day of September One thousand
eight hundred and seventy.