K, K, &c., in the view of the lower line, are the steam cylinders for
drying the endless sheet.
_i_, _i_ are rollers to convey the paper.
_j_, _j_ are rollers to conduct the felt; which serves to support the
paper, and prevent it wrinkling or becoming cockled.
D, D are the hexagonal expanding reels for the steam-dried paper web,
one only being used at a time, and made to suit different sizes of
sheets. _l_ is their swing fulcrum.
F, F, F, F, is the frame of the machine.
The deckle straps are worthy of particular notice in this beautiful
machine. They are composed of many layers of cotton tape, each one inch
broad, and together one half-inch thick, cemented with caoutchouc, so as
to be at once perfectly flexible and water-tight.
The upper end of each of the two carriages of the roller L is of a
forked shape, and the pivots of the roller are made to turn in the cleft
of the forked carriages in such a manner, that the roller may be
prevented from having any lateral motion, while it possesses a free
vibratory motion upwards and downwards; the whole weight of the roller L
being borne by the endless web of woven wire.
[Illustration: 789 790]
The greatest difficulty formerly experienced in the paper manufacture
upon the continuous system of Fourdrinier, was to remove the moisture
from the pulp, and condense it with sufficient rapidity, so as to
prevent its becoming what is called _water-galled_, and to permit the
web to proceed directly to the drying cylinders. Hitherto no invention
has answered so well in practice to remove this difficulty as the
channelled and perforated pulp rollers or dandies of Mr. John Wilks, the
ingenious partner of Mr. Donkin; for which a patent was obtained in
1830. Suppose one of these rollers (see L, in _fig._ 788., and M, M, in
_fig._ 793.,) is required for a machine which is to make paper 54 inches
wide, it must be about 60 inches long, so that its extremities (see
_figs._ 789. and 790.) may extend over or beyond each edge of the sheet
of paper upon which it is laid. Its diameter may be 7 inches. About 8
grooves, each 1-16th of an inch wide, are made in every inch of the
tube; and they are cut to half the thickness of the copper, with a
rectangularly shaped tool. A succession of ribs and grooves are thus
formed throughout the whole length of the tube. A similar succession is
then made across the former, but of 24 in the inch, and on the opposite
surface of the metal, which by a peculiar mode of management had been
prepared for that purpose. As the latter grooves are cut as deep as the
former, those on the inside meet those on the outside, crossing each
other at right angles, and thereby producing so many square holes;
leaving a series of straight copper ribs on the interior surface of the
said tube, traversed by another series of ribs coiled round them on the
outside, forming a cylindrical sieve made of one piece of metal. The
rough edges of all the ribs must be rounded off with a smooth file into
a semicircular form. _Figs._ 789. and 790., A A, are portions of the
ribbed copper tube. _Fig._ 789. shows the exterior, and _fig._ 790. the
interior surface; _b_, _b_ and _b_, _b_ show the plain part at each of
the ends, where it is made fast to the brass rings by rivets or screws;
C, C are the rings with arms, and a centre piece in each, for fixing the
iron pivot or shaft B; one such pivot is fixed by riveting it in each of
the centre pieces of the rings, as shown at _c_, _fig._ 790.; so that
both the said pieces shall be concentric with the rings, and have one
common axis with each other, and with the roller. At _a_, _a_, a groove
is turned in each of the pivots, for the purpose of suspending a weight
by a hook, in order to increase the pressure upon the paper, whenever it
may be found necessary.
[Illustration: 791 792]
_Fig._ 791. is an end view, showing the copper tube and its internal
ribs A, A; the brass rings C, C; arm D, D, D; centre piece E, and pivot
B. _Fig._ 792. is a section of the said ring, with the arms, &c.
The roller is shown at L, _fig._ 788., as lying upon the surface of the
wire-web. The relative position of that perforated roller, and the
little roller _b_, over which it lies, is such that the axis of L is a
little to one side of the axis of _b_, and not in the same vertical
plane, the latter being about an inch nearer the vat end. Hence,
whenever the wire-web is set in progressive motion, it will cause the
roller L to revolve upon its surface; and as the paper is progressively
made, it will pass onwards with the web under the surface of the roller.
Thus the pulpy layer of paper is condensed by compression under the
ribbed roller; while it transmits its moisture through the perforations,
it becomes sufficiently compact to endure the action of the wet press
rollers H, H, and also acquires the appearance of parallel lines, as if
made by hand in a laid mould.
Mr. Wilks occasionally employs a second perforated roller in the same
paper machine, which is then placed at the dotted lines _i_, _i_, _i_.
The patentee has described in the same specification a most ingenious
modification of the said roller, by which he can exhaust the air from a
hollowed portion of its periphery, and cause the paper in its passage
over the roller to undergo the sucking operation of the partial void, so
as to be remarkably condensed; but he has not been called upon to apply
this second invention, in consequence of the perfect success which he
has experienced in the working of the first.
The following is a more detailed illustration of Mr. Wilks’ improved
roller.
[Illustration: 793]
_Fig._ 793. represents two parts of his double-cased exhausting
cylinder.
This consists of two copper tubes, one nicely lining the other; the
inner being punched full of round holes, as at K, K, where that tube is
shown uncovered: a portion of the inner surface of the same tube is
shown at L, L. In this figure also, two portions of the outer tube are
shown at M, M, and N, N; the former being an external, and the latter an
internal view. Here we see that the external tube is the ribbed
perforated one already described; the holes in the inner tube being made
in rows to correspond with the grooves in the outer. The holes are so
distributed that every hole in one row shall be opposite to the middle
of the space left between two holes in the next row, as will appear from
inspection of the figure. The diameter of each of the punched holes
somewhat exceeds the width of each rib in the inside of the outer
cylinder, and every inside groove of this tube coincides with a row of
holes in the former, which construction permits the free transudation or
percolation of the water out of the pulp. At each end of this
double-case cylinder, a part is left at N, N, plain without, and grooved
merely in the inside of the outer tube. The smooth surface allows the
brass ends to be securely fixed; the outer edge of the brass ring fits
tight into the inside of the end of the cylinders.
On the inside of each of these rings there are four pieces which project
towards the centre or axis of the cylinder; two of which pieces are
shown at _a_, _a_, _fig._ 793. in section. _b_, _b_, is a brass ring
with four arms _c_, _c_, _c_, _c_, and a boss or centre piece _d_, _d_.
The outer edge of the last-mentioned ring is also turned cylindrical,
and of such a diameter as to fit the interior of the former ring _o_,
_o_. The two rings are securely held together by four screws. _e_, _e_
is the hollow iron axle or shaft upon which the cylinder revolves. Its
outside is made truly cylindrical, so as to fit the circular holes in
the bosses _d_, _d_, of the rings and arms at each end of the cylinder.
Hence, if the hollow shaft be so fixed that it will not turn, the
perforated cylinder is capable of having a rotatory motion given to it
round that shaft. This motion is had recourse to, when the vacuum
apparatus is employed. But otherwise the cylinder is made fast to the
hollow axle by means of two screw clamps. To one end of the cylinder, as
at _p_, a toothed wheel is attached, for communicating a rotatory motion
to it, so that its surface motion shall be the same as that of the paper
web; otherwise a rubbing motion might ensue, which would wear and injure
both.
The paper stuff or pulp is allowed to flow from the vat A, _fig._ 788.,
on to the surface of the endless wire-web, as this is moving along. The
lines _o_, _o_, _fig._ 788. show the course of the motion of the web,
which operates as a sieve, separating to a certain degree the water from
the pulp, yet leaving the latter in a wet state till it arrives at the
first pair of pressing rollers H, H, between which the web with its
sheet of paper is squeezed. Thick paper, in passing through these
rollers, was formerly often injured by becoming water-galled, from the
greater retention of water in certain places than in others. But Messrs.
Donkin’s cylinder, as above described, has facilitated vastly the
discharge of the water, and enabled the manufacturer to turn off a
perfectly uniform smooth paper.
In _fig._ 788., immediately below the perforated cylinder, there is a
wooden water-trough. Along one side of the trough a copper pipe is laid,
of the same length as the cylinder, and parallel to it; the distance
between them being about one fourth of an inch. The side of the pipe
facing the cylinder is perforated with a line of small holes, which
transmit a great many jets of water against the surface of the cylinder,
in order to wash it and keep it clean during the whole continuance of
the process.
The principle adopted by John Dickinson, Esq., of Nash Mill, for making
paper, is different from that of Fourdrinier. It consists in causing a
polished hollow brass cylinder, perforated with holes or slits, and
covered with wire cloth, to revolve over and just in contact with the
prepared pulp; so that by connecting the cylinder with a vessel
exhausted of its air, the film of pulp, which adheres to the cylinder
during its rotation, becomes gently pressed, whereby the paper is
supposed to be rendered drier, and of more uniform thickness, than upon
the horizontal hand moulds, or travelling wire cloth of Fourdrinier.
When subjected merely to agitation, the water is sucked inwards through
the cylindric cage, leaving the textile filaments so completely
interwoven as, if felted among each other, that they will not separate
without breaking, and, when dry, they will form a sheet of paper of a
strength and quality relative to the nature and preparation of the pulp.
The roll of paper thus formed upon the hollow cylinder is turned off
continuously upon a second solid one covered with felt, upon which it is
condensed by the pressure of a third revolving cylinder, and is thence
delivered to the drying rollers.
Such is the general plan of Mr. Dickinson’s paper machines, into which
he has introduced numerous improvements since its invention in 1809,
many of them secured by patent right; whereby he has been enabled to
make papers of first-rate quality, more particularly for the
printing-press. See _infrà_.
In July 1830, Mr. Ibotson of Poyle, paper manufacturer, obtained a
patent, see B, _fig._ 788., which has proved very successful, for a
peculiar construction of a sieve or strainer. Instead of wire meshes, he
uses a series of bars of gun-metal, laid in the bottom of a box, very
closely together, so that the upper surfaces or the flat sides may be in
the same plane, the edge of each bar being parallel with its neighbour,
leaving parallel slits between them of from about 1-70th to 1-100th of
an inch in width, according to the fineness or coarseness of the
paper-stuff to be strained. As this stuff is known to consist of an
assemblage of very fine flexible fibres of hemp, flax, cotton, &c.,
mixed with water, and as, even in the pulp of which the best paper is
made, the length of the said fibres considerably exceeds the diameter of
the meshes of which common strainers are formed, consequently the
longest and most useful fibres were formerly lost to the paper
manufacturer. Mr. Ibotson’s improved sieve is employed to strain the
paper-stuff previously to its being used in the machine above described.
(see its place at B in the vat.) When the strainer is at work, a quick
vertical and lateral jogging motion is given to it, by machinery similar
to the joggling-screens of corn mills.
Since the lateral shaking motion of the wire-web in the Fourdrinier
machine, as originally made, was injurious to the fabric of the paper,
by bringing its fibres more closely together breadthwise than
lengthwise, thus tending to produce long ribs, or thick streaks in its
substance, Mr. George Dickinson, of Buckland Mill, near Dover, proposed,
in the specification of a patent obtained in February, 1828, to give a
rapid up-and-down movement to the travelling web of pulp. He does not,
however, define with much precision any proper mechanism for effecting
this purpose, but claims every plan which may answer this end. He
proposes generally to mount the rollers, which conduct the horizontal
endless web, upon a vibrating frame. The forepart of this frame is
attached, to the standards of the machine, by hinge joints, and the
hinder part, or that upon which the pulp is first poured out, is
supported by vertical rods, connected with a crank on a shaft below.
Rapid rotatory motion being given to this crank-shaft, the hinder part
of the frame necessarily receives a quick up-and-down vibratory
movement, which causes the water to be shaken out from the web of pulp,
and thus sets the fibres of the paper with much greater equality than in
the machines formerly constructed. A plan similar to this was long ago
introduced into Mr. Donkin’s machines, in which the vibrations were
actuated in a much more mechanical way.
John Dickinson, Esq., of Nash Mill, obtained a patent in October, 1830,
for a method of uniting face to face two sheets of pulp by means of
machinery, in order to produce paper of extraordinary thickness. Two
vats are to be supplied with paper stuff as usual; in which two hollow
barrels or drums are made to revolve upon axles driven by any first
mover; an endless felt is conducted by guide rollers, and brought into
contact with the drums; the first drum gives off the sheet of paper pulp
from its periphery to the felt, which passing over a pressing roller, is
conducted by the felt to that part of a second drum which is in contact
with another pressing roller. A similar sheet of paper pulp is now given
off from the second drum, and it is brought into contact with the former
by the pressure of its own roller. The two sheets of paper pulp thus
united are carried forward by the felt over a guide roller, and onward
to a pair of pressing rollers, where by contact the moist surfaces of
the pulp are made to adhere, and to constitute one double thick sheet of
paper, which, after passing over the surfaces of hollow drums, heated by
steam, becomes dry and compact. The rotatory movements of the two
pulp-lifting drums must obviously be simultaneous, but that of the
pressing rollers should be a little faster, because the sheets extend by
the pressure, and they should be drawn forward as fast as they are
delivered, otherwise creases would be formed. Upon this invention is
founded Mr. Dickinson’s ingenious method of making safety-paper for
Post-office stamps, by introducing silk fibres, &c., between the two
laminæ.
The following contrivance of the same inventive manufacturer is a
peculiarly elegant mechanical arrangement, and is likely to conduce to
the perfection of machine-made paper. I have already described Mr.
Ibotson’s excellent plan of parallel slits, or gridiron strainers, which
has been found to form paper of superior quality, because it permits all
the elongated tenacious fibres to pass, which give strength to the
paper, while it intercepts the coarser knots and lumps of the paste,
that were apt to spoil its surface. Mr. Turner’s circular wire sieves,
presently to be noticed, may do good work, but they cannot compete with
Mr. Dickinson’s present invention, which consists in causing the diluted
paper pulp to pass between longitudinal apertures, about the
hundred-and-fifteenth part of an inch wide, upon the surface of a
revolving cylinder.
The pulp being diluted to a consistency suitable for the paper machine,
is delivered into a vat, of which the level is regulated by a waste
pipe, so as to keep it nearly full. From this vat there is no other
outlet for the pulp, except through the wire-work periphery of the
revolving cylinder, and thence out of each of its ends into troughs
placed alongside, from which it is conducted to the machine destined to
convert it into a paper web.
The revolving cylinder is constructed somewhat like a squirrel cage, of
circular rods, or an endless spiral wire, strengthened by transverse
metallic bars, and so formed that the spaces between the rings are
sufficient to allow the slender fibres of the pulp to pass through, but
are narrow enough to intercept the knots and other coarse impurities,
which must of course remain, and accumulate in the vat. The spaces
between the wires of the squirrel cage may vary from the interval above
stated, which is intended for the finest paper, to double the distance
for the coarser kinds.
It has been stated that the pulp enters the revolving cylinders solely
through the intervals of the wires in the circumference of the cylinder;
these wires or rods are about three-eighths of an inch broad without,
and two-eighths within, so that the circular slits diverge internally.
The rods are one quarter of an inch thick, and are riveted to the
transverse bars in each quadrant of their revolution, as well as at
their ends to the necks of the cylinder.
During the rotation of the cylinder, its interstices would soon get
clogged with the pulp, were not a contrivance introduced for creating a
continual vertical agitation in the inside of the cylinder. This is
effected by the up-and-down motion of an interior agitator or plunger,
nearly long enough to reach from the one end of the cylinder to the
other, made of stout copper, and hollow, but water-tight. A metal bar
passes through it, to whose projecting arm at each end a strong link is
fixed; by these two links it is hung to two levers, in such a way that
when the levers move up and down, they raise and depress the agitator,
but they can never make it strike the sides of the cylinder. Being
heavier than its own bulk of water, the agitator, after being lifted by
the levers, sinks suddenly afterwards by its weight alone.
The agitator’s range of up-and-down movement should be about one inch
and a quarter, and the number of its vibrations about 80 or 100 per
minute; the flow of the pulp through the apertures is suddenly checked
in its descent, and promoted in its ascent, with the effect of
counteracting obstructions between the ribs of the cylinder.
The sieve cylinder has a toothed wheel fixed upon the tubular part of
one of its ends, which works between two metal flanches made fast to the
wooden side of the vat, for the purpose of keeping the pulp away from
the wheel; and it is made to revolve by a pinion fixed on a spindle,
which going across the vat, is secured by two plummer blocks on the
outside of the troughs, and has a rotatory motion given to it by an
outside rigger or pulley, by means of a strap from the driving shaft, at
the rate of 40 or 50 revolutions per minute. This spindle has also two
double eccentrics fixed upon it, immediately under the levers, so that
in every revolution it lifts those levers twice, and at the same time
lifts the agitator.
The diameter of the sieve cylinder is not very material, but 14 inches
have been found a convenient size; its length must be regulated
according to the magnitude of the machine which it is destined to supply
with pulp. One, four feet long in the cage part, is sufficient to supply
a machine of the largest size in ordinary use, viz., one capable of
making paper 4 feet 6 inches wide. When the cylinder is of this length,
it should have a wheel and pinion at each end.
Metal flanches are firmly fixed to the sides of the vat, with a
water-tight joint, and form the bearings in which the cylinder works.
Mr. Turner of Bermondsey, paper-maker, obtained a patent in March, 1831,
for a peculiar strainer, designed to arrest the lumps mixed with the
finer paper pulp, whereby he can dispense with the usual vat and hog in
which the pulp is agitated immediately before it is floated upon the
endless wire-web of the Fourdrinier apparatus. His strainer may also be
applied advantageously to hand paper machines. He constructs his sieves
of a circular form, by combining any desirable number of concentric
rings of metal, with small openings between them, from the 50th to the
100th part of an inch wide. In order to facilitate the passage of the
fine pulp and water, the sieves receive a vibratory motion up and down,
which supersedes the hog employed in other paper-making machines.
A mechanism to serve the same purpose as the preceding, in which Mr.
Ibotson’s plan of a parallel rod-strainer is modified, was made the
subject of a patent by Mr. Henry Brewer, of Surrey Place, Southwark, in
March, 1832. He constructs square boxes with gridiron bottoms, and gives
a powerful up-and-down vibration in the pulp tub, by levers, rotatory
shafts, and cranks.
As the contrivance is not deficient in ingenuity, and may be useful, I
shall describe this mode of adapting his improved strainers to a vat in
which paper is to be made by hand moulds. A hog (or churning rotator) is
employed for the purpose of agitating the pulp at the bottom of the vat,
in which the sieve is suspended from a crank-shaft, or in any other way,
so as to receive the up-and-down vibratory motion for the purpose of
straining the pulp. The pulp may be supplied from a chest, and passed
through a cock into a trough, by which it is conveyed to the strainers.
A pipe from the bottom of the vat leads into a lifter-box, which is
designed to convey thin pulp into the sieve, in order to dilute that
which is delivered from the chest. This pipe also allows the small
lumps, called rolls, to be re-sifted. The pressure of the pulp and water
in the vat forces the pulp up the pipe into the lifter-box, whence it is
taken by rotatory lifters, and discharged into a trough, where it runs
down and mixes with the thick pulp from the chest, as before mentioned.
By these means the contents of the vat are completely strained or sifted
over again in the course of almost every hour.
A patent was obtained for a paper-pulp strainer by Mr. Joseph Amies, of
Loose, in the county of Kent, paper manufacturer, who makes the bottoms
of his improved strainers with plates of brass or other suitable metal,
and forms the apertures for the fine fibres of pulp to pass through, by
cutting short slits through such plates, taking care that as much metal
is left between the ends of each short slit and the next following as
will properly brace or stiffen the ribs of the strainer; and he prefers
that the end of one slit shall be nearly opposite to the middle of the
two slits next adjoining it, which is commonly called blocking the
joints. This is for giving rigidity to the bottom of the strainer, and
constitutes the main feature of his improvement. The bottoms of sieves
previously constructed with long metallic rods, he considers to be
liable to lateral vibration in use, and thus to have permitted knots and
lumps to pass through their expanded intervals. This objection is not
applicable to Mr. Dickinson’s squirrel-cage strainer, of which the ribs
may be made rigid by a sufficient number of transverse bars; nor in fact
is it applicable to Mr. Ibotson’s original strainer, as it is admirably
constructed by Messrs. Donkin and Co. Each bar which they make being
inflexible by a feathered rib, is rendered perfectly straight in its
edge by grinding with emery upon a flat disc-wheel of block tin, and of
invariable length, by a most ingenious method of turning each set of
bars in a lathe. The bars are afterwards adjusted in the metallic
sieve-frame, or chest, at any desired distance apart, from the 120th to
the 60th of an inch, in such a manner as secures them from all risk of
derangement by the vibratory or jogging motion in shaking the pulpy
fibres through the lineal intervals between them.
Mr. James Brown, paper manufacturer, of Esk mills, near Edinburgh,
obtained a patent in May, 1836, for a particular mode of applying
suction to the pasty web in the Fourdrinier’s machine. He places a
rectangular box transversely beneath the horizontal wire cloth, without
the interposition of any perforated covering, such as had been tried in
the previously constructed vacuum machines, and which he considers to
have impeded their efficacy in condensing the pulp and extracting the
water.
Upon this and all similar contrivances for making a partial vacuum under
the pulpy paper web, it may be justly remarked, that they are more apt
to injure than improve the texture of the article; since when the
suction is unequally operative, it draws down not only the moisture, but
many of the vegetable fibres, causing roughnesses, and even numerous
small perforations in the paper.
A modification of Mr. Dickinson’s cylinder-mould continuous paper
machine was made the subject of a patent in Nov. 1830, by Mr. John Hall,
jun., of Dartford, as communicated to him by a foreigner residing
abroad. The leading feature of the invention is a mode of supplying the
vat in which the wire cylinder is immersed with a copious flow of water,
for the purpose of creating a considerable pressure upon the external
surface of the cylinder, and thereby causing the fibres of the paper
pulp to adhere to the mould.
There is a semi-cylindrical trough, in which the mould is immersed, and
made to revolve by any convenient means. The pulp is transferred from
the vat into that vessel at its bottom part. On the side of the
drum-mould opposite to the vat, there is a cistern into which a copious
flow of water is delivered, which passes thence into the
semi-cylindrical trough. In the interior of the cylindrical mould, a
bent or syphon tube is introduced, on the horizontal part of which tube,
inside, the mould revolves. This tube is connected at the outside to a
pump, by which the water is drawn from the interior of the cylindrical
mould. Thus the water in the semi-cylindrical trough, on the outside of
the drum, is kept at a considerably higher level than it is within; and
consequently the pressure of the water, as it passes through the wire
gauze, will, it is supposed, cause the fibres of the paper pulp to
adhere to the circumference of the mould. The water which is withdrawn
from the interior of the drum by the recurved tube, is conducted round
into the cistern, where its discharge is impeded by several vertical
partitions, which make the water flow in a gentle stream into the
semi-cylindrical mould vat. In order to keep the pulp properly agitated
in the mould vat, a segment frame, having rails extended across the vat,
is moved to and fro; as the drum mould goes round, the fibres of the
pulp are forced against its circumference, and as the water passes
through, the fibres adhere, forming the sheet of paper, which, on
arriving at a couching roller above, is taken up as usual by an endless
felt, conducted away to the drying apparatus, and thence to the reel to
be wound up.
The patentee claims merely the application of a pump to draw the water
from the interior of the mould drum, and to throw it upon its external
surface.
A rag-cutting and lacerating machine was patented by Mr. Henry Davy, of
Camberwell, in September, 1833, being a communication from a foreigner
residing abroad. The machine consists of an endless feeding-cloth, by
which the rough rags supplied by the attendants are progressively
conducted forwards to a pair of feed-rollers (see COTTON, _spinning_),
and on passing through these rollers, the rags are subjected to the
operation of rotatory cutters, acting against a fixed or ledger blade,
which cut and tear them to pieces. Thence the rags pass down an inclined
sieve, upon which they are agitated to separate the dust. The cleaned
fragments are delivered on to a horizontal screen or sorting table, to
suffer examination. When picked here, they are ready for the
pulp-engine. A distinct representation of this machine is given in
Newton’s Journal, conjoined series, vol. iv. pl. IX. _fig._ 1.
Mr. Jean Jacques Jequier obtained a patent in August, 1831, for a mode
of making paper on the continuous machine with wire-marks. The proposed
improvement consists merely in the introduction of a felted pressing
roller, to act upon the paper after it has been discharged from the
mould, and need not therefore be particularly described.
In August, 1830, Mr. Thomas Barratt, paper-maker, of St. Mary Cray, in
the county of Kent, obtained a patent for an apparatus by which paper
may be manufactured in a continuous sheet, with the water-mark and
maker’s name, so as to resemble in every respect paper made by hand, in
moulds the size of each separate sheet. On the wire web, at equal
distances apart, repetitions of the maker’s name or other device is
placed, according to the size of the paper when cut up into single
sheets. In manufacturing such paper, the ordinary method of winding upon
a reel cannot be employed; and therefore the patentee has contrived a
compensating reel, whose diameter diminishes at each revolution, equal
to the thickness of a sheet of paper. See Newton’s Journal, C. S. vol.
vii. p. 285.
For Mr. Lemuel Wellman Wright’s series of improvements in the
manufacture of paper, specified in his patent of November, 1834, I must
refer to the above Journal, C. S., vol. viii. p. 86.
A committee of the _Société d’Encouragement_, of Paris, made researches
upon the best composition for sizing paper in the vat, and gave the
following recipe:--
100 kilogrammes of dry paper stuff.
12 -- starch.
1 -- rosin, previously dissolved in 500 grammes of
carbonate of soda.
18 pails of water.
M. Braconnot proposed the following formula in the 23d volume of the
_Annales de Chimie et de Physique_:--To 100 parts of dry stuff, properly
diffused through water, add a boiling uniform solution of 8 parts of
flour, with as much caustic potash as will render the liquor clear. Add
to it one part of white soap previously dissolved in hot water. At the
same time heat half a part of rosin with the requisite quantity of weak
potash lye for dissolving the rosin; mix both solutions together, and
pour into them one part of alum dissolved in a little water.
Those who colour prints, size them previously with the following
composition:--4 ounces of glue, and 4 ounces of white soap dissolved in
3 English pints of hot water. When the solution is complete, two ounces
of pounded alum must be added, and as soon as the composition is made
homogeneous by stirring, it is ready for use. It is applied cold with a
sponge, or rather with a flat camel’s hair brush. Ackermann’s liquor, as
analyzed by Vauquelin, may be made for sizing paper as follows:--
100 kilogrammes of dry stuff.
4 -- glue.
8 -- resinous soap.
8 -- alum.
The soap is made from 4·8 kilos. of pounded rosin, and 2·22 crystals of
carbonate of soda, dissolved in 100 litres of water. It is then boiled
till the mixture becomes quite uniform; the glue, previously softened by
12 hours’ maceration in cold water, is to be next added; and when this
is totally dissolved, the solution of alum in hot water is poured in.
Three quarts of this size were introduced into the vat with the stuff,
and well mixed with it. The paper manufactured with this paste seemed to
be of excellent quality, and well sized.
The Chinese, in manufacturing paper, sometimes employ linen rags, as we
do; at other times, the fibres of the young bamboo; of the mulberry; the
envelope of the silk-worm cocoon; also a tree, unknown to our botanists,
which the natives call _chu_ or _ko-chu_; cotton down, and especially
the cotton tree. The processes pursued in China to make paper with the
inner bark of their _paper-tree_ (_Broussonetia-papyrifera_,) or Chinese
mulberry, have been described at great length in the bulletin of the
Société d’Encouragement, for 1826, p. 226; but they will hardly prove
serviceable to a European manufacturer. That tree has been acclimated in
France.
Chinese paper is not so well made as the good paper of Europe; it is not
so white, it is thinner, and more brittle, but extremely soft and silky.
The longitudinal tenacity of its filaments, however, renders it fitter
for the engraver than our best paper. The Chinese, after triturating,
grinding, and boiling the bamboo, set the paste to ferment in a heap
covered with mats. Chinese paper is readily recognised, because it is
smooth on one side, and bears on the other, the marks of the brush with
which it is finished, upon smooth tables, in order to dry it flat. The
kind employed for engravings is in sheets four feet long, and two broad.
It is made of the bamboo; their myrtle-tree paper would be too strong
for this purpose.
_Tracing Paper._
The best paper of this kind, sometimes superfluously called vegetable
paper, is made of the refuse of the flax mills, and prepared by the
engine without fermentation. It thus forms a semi-transparent paste, and
affords a transparent paper. Bank-note paper is made of the same
materials, but they always undergo a bleaching with chloride of lime.
Great nicety is required in drying this kind of paper. For this purpose,
each sheet must be put between two sheets of gray paper in the press;
and this gray paper must be renewed several times, to prevent the
bank-note paper from creasing.
_Paper of Safety or Surety; Papier de Sureté._
This subject has occupied the attention of the French Academy for many
years, in consequence of the number of frauds committed upon the stamp
revenue in France. One of the best methods of making a paper which would
evince whether any part of a writing traced upon it had been tampered
with or discharged, is to mix in the vat two kinds of pulp, the one
perfectly white, the other dyed of any colour easily affected by
chlorine, acids, and alkalis. The latter stuff being mingled with the
former in any desired proportion, will furnish a material for making a
paper which will contain coloured points distributed throughout all its
substance, ready to show, by the changes they suffer, whether any
chemical reaction has been employed.
Quantity of Paper charged with Duties of Excise, in the United Kingdom,
in
+--------------------------+-------------+-------------+-------------+
| | 1834. | 1835. | 1836. |
+--------------------------+-------------+-------------+-------------+
| | _lbs._ | _lbs._ | _lbs._ |
|First class | 54,053,721 | 56,179,555 | 66,202,689 |
|Second class | 16,552,168 | 7,863,095 | 15,906,258 |
|Pasteboard, millboard, &c.| 49,392 | 49,772 | 36,340 |
| | _yards._ | _yards._ | _yards._ |
|Stained | 8,749,144 | 8,247,931 | 8,032,577 |
+--------------------------+-------------+-------------+-------------+
| | _£ s. d._| _£ s. d._| _£ s. d._|
|Amount of duty, | | | |
| first class |675,671 10 0|702,244 9 0|651,699 0 0|
| -- second class |103,451 0 0|111,644 0 0| 99,414 0 0|
| -- pasteboard, &c. | 54,689 0 0| 54,548 15 0| 39,557 0 0|
| -- stained | 63,795 16 0| 60,141 0 0| 22,112 0 0|
+--------------------------+-------------+-------------+-------------+
The late reduction of the duty, from 3_d._ to 1-1/2_d._ per lb., upon
paper of the first class, viz., on all descriptions of it, except that
made out of tarred ropes only, has been already attended with
considerable benefit to the manufacture, and would have acted with much
greater effect, but for the American crisis. The gross amount of the
paper duty in the year ending 5th January, 1836, was 831,057_l._, and in
the year ending 5th January, 1838, it was 554,497_l._; instead of being
little more than one half, as might have been the case from the
reduction of the duty, which only came into full operation in the year
1837. At the same time that the tax on common paper was reduced, that
upon stained paper was repealed altogether. The effect of the diminution
consequently made in the price of paper-hangings, has been so great as
nearly to double the consumption of the country, while the manufacture
appears to be still rapidly on the increase.