STATISTICAL TABLE of LAC-DYE and LAC-LAKE, per favour of James
Wilkinson, Esq., of Leadenhall-street.
+----+---------+-------+-------------+-------------+---------+
| | Import. |Export.| Home | Prices. | Stocks. |
| | | |Consumption. | | |
+----+---------+-------+-------------+-------------+---------+
| | _lbs._ | _lbs._| _lbs._ |_s. d. s. d._|_Chests._|
|1802| 253| none | none | | |
|1803| 1,735| |accot. burned| | |
|1804| 531| | | | |
|1805| 1,987| | | | |
|1806| none | | | | |
|1807| 25,350| | | | |
|1808| 5,731| | | | |
|1809| 40,632| | | | |
|1810| 235,154| | | | |
|1811| 378,325| | | | |
|1812| 198,250| | | | |
|1813| 289,654| | | | |
|1814| 278,899| 5,071| 133,935 | | |
|1815| 598,592| 8,441| 137,915 | | |
|1816| 269,373| 27,412| 162,894 | | |
|1817| 384,909| 23,091| 234,763 | | |
|1818| 242,572| 32,079| 323,169 | | |
|1819| 179,511| 21,707| 207,063 | | |
|1820| 441,486| 49,519| 912,514 | | |
|1821| 641,755| 91,925| 322,837 | | |
|1822| 872,967| 29,578| 349,351 | | |
|1823| 534,220| 13,050| 414,714 | | |
|1824| 604,269| 53,843| 483,339 | | |
|1825| 541,443| 61,908| 385,734 | | |
|1826| 760,729| 68,603| 395,609 | | |
|1827| 756,315| 76,875| 448,270 | 1 9 4 0 | 11,538 |
|1828| 512,874| 54,999| 397,867 | 1 3 3 9 | 11,085 |
|1829| 475,632| 39,344| 433,851 | 1 3 3 6 | 11,976 |
|1830| 534,341| 78,099| 548,865 | 0 9 3 3 | 11,834 |
|1831| 913,562|175,717| 597,568 | 0 4 2 6 | 12,559 |
|1832| 378,843| 69,842| 594,155 | 0 4 2 3 | 11,420 |
|1833| 326,894| 66,447| 426,460 | 0 9 2 4 | 11,457 |
|1834| 708,959| 89,229| 398,832 | 0 11 2 4 | 11,928 |
|1835| 528,564|203,840| 573,288 | 0 11 3 0 | 10,454 |
|1836| 642,436|200,975| 642,615 | 1 0 4 0 | 9,492 |
|1837|1,011,674|133,959| 427,890 | 1 0 3 9 | 8,780 |
+----+---------+-------+-------------+-------------+---------+
| The Stock includes 2,200 chests of Lac-lake. |
+------------------------------------------------------------+
LACCIC ACID crystallizes, has a wine-yellow colour, a sour taste, is
soluble in water, alcohol, and ether. It was extracted from stick-lac by
Dr. John.
LACCINE is the portion of shell-lac which is insoluble in boiling
alcohol. It is brown, brittle, translucid, consisting of agglomerated
pellicles, more like a resin than any thing else. It is insoluble in
ether and oils. It has not been applied to any use.
LACE MANUFACTURE. The pillow-made, or bone-lace, which formerly gave
occupation to multitudes of women in their own houses, has, in the
progress of mechanical invention, been nearly superseded by the
bobbin-net lace, manufactured at first by hand-machines, as stockings
are knit upon frames, but recently by the power of water or steam. This
elegant texture possesses all the strength and regularity of the old
Buckingham lace, and is far superior in these respects to the point-net
and warp lace, which had preceded, and in some measure paved the way for
it. Bobbin-net may be said to surpass every other branch of human
industry in the complex ingenuity of its machinery; one of Fisher’s
spotting frames being as much beyond the most curious chronometer in
multiplicity of mechanical device, as that is beyond a common
roasting-jack.
[Illustration: 608]
The threads in bobbin-net lace form, by their intertwisting and
decussation, regular hexagonal holes or meshes, of which the two
opposite sides, the upper and under, are directed along the breadth of
the piece, or at right angles to the selvage or border. _Fig._ 608.
shows how, by the crossing and twisting of the threads, the regular
six-sided mesh is produced, and that the texture results from the union
of three separate sets of threads, of which one set proceed downwards in
serpentine lines, a second set proceeds from the left to the right, and
a third from the right to the left, both in slanting directions. These
oblique threads twist themselves round the vertical ones, and also cross
each other betwixt them, in a peculiar manner, which may be readily
understood by examining the representation. In comparing bobbin-net with
a common web, the perpendicular threads in the figure, which are
parallel to the border, may be regarded as the warp, and the two sets of
slanting threads, as the weft.
[Illustration: 609]
These warp threads are extended up and down, in the original mounting of
the piece between a top and bottom horizontal roller or beam, of which
one is called the warp beam, and the other the lace beam, because the
warp and finished lace are wound upon them respectively. These straight
warp threads receive their contortion from the tension of the weft
threads twisted obliquely round them alternately to the right and the
left hand. Were the warp threads so tightly drawn that they became
inflexible, like fiddle-strings, then the lace would assume the
appearance shown in _fig._ 609.; and although this condition does not
really exist, it may serve to illustrate the structure of the web. The
warp threads stand in the positions _a a_, _a´ a´_, and _a´´ a´´_; the
one half of the weft proceeds in the direction _b b_, _b´ b´_ and _b´´
b´´_; and the second crosses the first by running in the direction _c
c_, or _c´ c´_, towards the opposite side of the fabric. If we pursue
the path of a weft thread, we find it goes on till it reaches the
outermost or last warp thread, which it twists about; not once, as with
the others, but twice; and then returning towards the other border,
proceeds in a reverse direction. It is by this double twist, and by the
return of the weft threads, that the selvage is made.
The ordinary material of bobbin-net is two cotton yarns, of from No.
180. to No. 250., twisted into one thread; but sometimes strongly
twisted single yarn has been used. The beauty of the fabric depends upon
the quality of the material, as well as the regularity and smallness of
the meshes. The number of warp threads in a yard in breadth is from 600
to 900; which is equivalent to from 20 to 30 in an inch. The size of the
holes cannot be exactly inferred from that circumstance, as it depends
partly upon the oblique traction of the threads. The breadth of the
pieces of bobbin-net varies from edgings of a quarter of an inch, to
webs 12, or even 20 quarters, that is, 5 yards wide.
[Illustration: 610 611]
Bobbin-net lace is manufactured by means of very costly and complicated
machines, called _frames_. The limits of this Dictionary will admit of
an explanation of no more than the general principles of the
manufacture. The threads for crossing and twisting round the warp, being
previously gassed, that is, freed from loose fibres by singeing with
gas, are wound round small pulleys, called bobbins, which are, with this
view, deeply grooved in their periphery. _Figs._ 610, 611. exhibit the
bobbin alone, and with its carriage. In the section of the bobbin _a_,
_fig._ 610., the deep groove is shown in which the thread is wound. The
bobbin consists of two thin discs of brass, cut out in a stamp-press, in
the middle of each of which there is a hollow space _c_. These discs are
riveted together, leaving an interval between their edge all round, in
which the thread is coiled. The round hole in the centre, with the
little notch at top, serves for spitting them upon a feathered rod, in
order to be filled with thread by the rotation of that rod in a species
of reel, called the bobbin-filling machine. Each of these bobbins (about
double the size of the figure), is inserted into the vacant space G of
the carriage, _fig._ 611. This is a small iron frame (also double the
size of the figure), which, at _e e_, embraces the grooved border of the
bobbin, and by the pressure of the spring at _f_, prevents it from
falling out. This spring serves likewise to apply sufficient friction to
the bobbin, so as to prevent it from giving off its thread at _g_ by its
rotation, unless a certain small force of traction be employed upon the
thread. The curvilinear groove _h h_, sunk in each face or side of the
carriage, has the depth shown in the section at _h_. This groove
corresponds to the interval between the teeth of the comb, or bars of
the bolt, in which each carriage is placed, and has its movement. A
portion of that bolt or comb is shown at _a_, _fig._ 612. in plan, and
one bar of a circular bolt machine at _b_, in section. If we suppose two
such combs or bolts placed with the ends of the teeth opposite each
other, but a little apart, to let the warp threads be stretched, in one
vertical plane, between their ends or tips, we shall have an idea of the
skeleton of a bobbin-net machine. One of these two combs, in the double
bolt machine, has an occasional lateral movement called _shogging_,
equal to the interval of one tooth or bolt, by which, after it has
received the bobbins, with their carriages, into its teeth, it can shift
that interval to the one side, and thereby get into a position to return
the bobbins, with their carriages, into the next series of interstices
or gates, in the other bolt. By this means the whole series of carriages
receives successive side steps to the right in one bolt, and to the left
in the other, so as to perform a species of countermarch, in the course
of which they are made to cross and twist round about the vertical warp
threads, and thus to form the meshes of the net.
[Illustration: 612]
The number of movements required to form a row of meshes in the double
tier machine, that is, in a frame with two combs or bars, and 2 rows of
bobbins, is six; that is, the whole of the carriages (with their
bobbins) pass from one bar or comb to the other six times, during which
passages the different divisions of bobbin and warp threads change their
relative positions 12 times.
[Illustration: 613]
This interchange or traversing of the carriages with their bobbins,
which is the most difficult thing to explain, but at the same time the
most essential principle of the lace-machine, may be tolerably well
understood by a careful study of _fig._ 613., in which the simple line |
represents the bolts or teeth, the sign ● the back line of carriages,
and the sign ○ the front line of carriages. H is the front comb or bolt
bar, and I the back bolt bar. The former remain is always fixed or
stationary, to receive the carriages as they may be presented to it by
the shogging of the latter. There must be always one odd carriage at the
end; the rest being in pairs.
No. 1. represents the carriages in the front comb or bar, the odd
carriage being at the left end. The back line of carriages is first
moved on to the back bar I, the odd carriage, as seen in No. 1., having
been left behind, there being no carriage opposite to drive it over to
the other comb or bar. The carriages then stand as in No. 2. The bar I
now shifts to the left, as shown in No. 3.; the front carriages then go
over into the back bar or comb, as is represented by No. 4. The bar I
now shifts to the right, and gives the position No. 5. The front
carriages are then driven over to the front bar, and leave the odd
carriage on the back bar at the right end, for the same reason as before
described, and the carriages stand as shown in No. 6. The bar I next
shifts to the left, and the carriages stand as in No. 7. (the odd
carriage being thereby on the back bar to the left.) The back carriages
now come over to the front bar, and stand as in No. 8. The back bar or
comb I shifts to the right as seen in No. 9., which completes the
traverse. The whole carriages with their bobbins have now changed their
position, as will be seen by comparing No. 9. with No. 1. The odd
carriage, No. 1. ○ has advanced one step to the right, and has become
one of the front tier; one of the back tier or line ● has advanced one
step to the left, and has become the odd carriage; and one of the front
ones ○ has gone over to the back line. The bobbins and carriages
throughout the whole width of the machine have thus crossed each other’s
course, and completed the mesh of net.
The carriages with their bobbins are driven a certain way from the one
comb to the other, by the pressure of two long bars (one for each)
placed above the level of the comb, until they come into such a position
that their projecting heels or catches _i i_, _fig._ 611., are moved off
by two other long flat bars below, called the locker plates, and thereby
carried completely over the interval between the two combs.
There are six different systems of bobbin-net machines. 1. Heathcoate’s
patent machine. 2. Brown’s traverse warp. 3. Morley’s straight bolt. 4.
Clarke’s pusher principle, single tier. 5. Leaver’s machine, single
tier. 6. Morley’s circular bolt. All the others are mere variations in
the construction of some of their parts. It is a remarkable fact, highly
honourable to the mechanical judgment of Mr. Morley of Derby, that no
machines except those upon his circular bolt principle, have been found
capable of working successfully by mechanical power.
The circular bolt machine (comb with curved teeth) was used by Mr.
Morley, for making narrow breadths or edgings of lace immediately after
its first invention, and it has been regularly used by the trade for
that purpose ever since, in consequence of the inventor having declined
to secure the monopoly of it to himself by patent. At that time the
locker bars for driving across the carriages had only one plate or
blade. A machine so mounted is now called “the single locker circular
bolt.” In the year 1824, Mr. Morley added another plate to each of the
locker bars, which was a great improvement on the machines for making
plain net, but an obstruction to the making of narrow breadths upon
them. This machine is now distinguished from the former by the term
“double locker.”[31]
[31] By reading the above brief account of Bobbin-net, in connexion
with the more detailed description of it in my COTTON MANUFACTURE OF
GREAT BRITAIN, a tolerably clear conception of the nature of this
intricate manufacture may be obtained.
A rack of lace, is a certain length of work counted perpendicularly, and
contains 240 meshes or holes. Well-made lace has the meshes a little
elongated in the direction of the selvage.
The term gauge, in the lace manufacture, means the number of gates,
slits, or interstices, in one inch of the bolt-bar or comb; and
corresponds therefore to the number of bobbins in an inch length of the
double tier. Thus, when we say “gauge nine points,” we mean that there
are nine gates with nine bobbins in one inch of the comb or bolt-bar.
Each of such bobbins with its carriage is therefore no more than one
ninth of an inch thick. The common proportion or gauge up and down the
machine is 16 holes in the inch for ten bobbins transversely. Circular
bolt double tier machines can turn off by steam power fully 360 racks
each day of 18 hours, with a relay of superintendents.
The number of new mechanical contrivances to which this branch of
manufacture has given rise, is altogether unparalleled in any other
department of the arts. Since Mr. Heathcoate’s first successful patent,
in 1809, a great many other patents have been granted for making lace.
In the year 1811, Mr. Morley, then of Nottingham, invented his straight
bolt frame, more simple in construction, better combined, and more easy
in its movements, than the preceding machines; but the modest inventor
did not secure it, as he might have done, by patent. The pusher machine
was invented in the same year, by Samuel Mart and James Clark, also of
Nottingham. The following year is remarkable in the history of the lace
trade, for the invention of the circular bolt machine, by Mr. Morley--a
mechanism possessing all the advantages of his straight bolt machine,
without its disadvantages.
Nearly at the same time Mr. John Leaver brought forward the lever
machine, conjointly with one Turton, both of New Radford, near
Nottingham. About the year 1817, or 1818, Mr. Heathcoate applied the
rotatory movement to the circular bolt machine, and mounted a
manufactory on that plan, by mechanical power, at Tiverton, after he and
his partner, Mr. Boden, had been driven from Loughborough, in 1816, by
the atrocious violence of the frame-destroying Luddites.
Such has been the progress of improvement and economy in this
manufacture, that the cost of labour in making a _rack_, which was,
twenty years ago, 3_s._ 6_d._, or 42 pence, is now not more than one
penny. The prices of this beautiful fabric have fallen in an equally
remarkable manner. At the former period, a 24 rack piece, five quarters
broad, fetched 17_l._ sterling, in the wholesale market; the same is now
sold for 7_s._! The consequence is, that in lace decoration, the maid
servant may now be more sumptuously arrayed than her mistress could
afford to be twenty years ago.
LACQUER, is a varnish, consisting chiefly of a solution of pale
shell-lac in alcohol, tinged with saffron, annotto, or other colouring
matters. See VARNISH.
LACTIC ACID. (_Acide Lactique_, Fr.; _Milchsäure_, Germ.) This acid was
discovered by Scheele in buttermilk, where it exists most abundantly;
but it is present also in fresh milk in small quantity, and communicates
to it the property of reddening litmus. Lactic acid may be detected in
all the fluids of the animal body; either free or saturated with
alkaline matter.
Scheele obtained this acid by evaporating the sour whey of clotted milk
to an eighth part of its bulk, saturating this remainder with slaked
lime, in order to throw down the subphosphate of lime held in solution,
filtering the liquor, diluting it with thrice its weight of water, and
precipitating the lime circumspectly, by the gradual addition of oxalic
acid. He next filtered, evaporated to dryness on a water bath, and
digested the residuum in strong alcohol, which dissolved the lactic
acid, and left the sugar of milk. On evaporating off the alcohol, the
acid was obtained. As thus procured, it requires to be purified by
saturation with carbonate of lead (pure white lead), and precipitating
the solution of this lactate with sulphate of zinc, not added in excess.
Sulphate of lead falls, and the supernatant lactate of zinc being
evaporated affords crystals, at first brown, but which become colourless
on being dissolved and re-crystallized twice or thrice. If the sulphuric
acid of the dissolved salt be thrown down by water of baryta, the liquid
when filtered and evaporated yields a pure lactic acid, of a syrupy
consistence, colourless and void of smell. It has a pungent acid taste,
which it loses almost entirely when moderately diluted with water. It
does not crystallize. Its salts, with the exception of those of magnesia
and zinc, have a gummy appearance, and are very soluble in alcohol,
unless they hold an excess of base. Lactic acid consists of 44·92
carbon; 6·55 hydrogen; 48·53 oxygen. It contains 9·92 per cent. of
water. It has not hitherto been applied to any use in the arts, except
by the Dutch in their old process of bleaching linen with sour milk.
LACTOMETER is the name of an instrument for estimating the quality of
milk, called also a _Galactometer_, which see. The most convenient form
of apparatus would be a series of glass tubes each about 1 inch in
diameter, and 12 inches long, graduated through a space of 10 inches, to
tenths of an inch, having a stop-cock at the bottom, and suspended
upright in a frame. The average milk of the cow being poured in to the
height of 10 inches, as soon as the cream has all separated at top, the
thickness of its body may be measured by the scale; and then the
skim-milk may be run off below into a hydrometer glass, in order to
determine its density, or relative richness in caseous matter.
LAKES. Under this title are comprised all those colours which consist of
a vegetable dye, combined by precipitation with a white earthy basis,
which is usually alumina. The general method of preparation is to add to
the coloured infusion a solution of common alum, or rather a solution of
alum saturated with potash, especially when the infusion has been made
with the aid of acids. At first only a slight precipitate falls,
consisting of alumina and the colouring matter; but on adding potash, a
copious precipitation ensues, of the alumina associated with the dye.
When the dyes are not injured, but are rather brightened by alkalis, the
above process is reversed; a decoction of the dye-stuff is made with an
alkaline liquor, and when it is filtered, a solution of alum is poured
into it. The third method is practicable only with substances having a
great affinity for subsulphate of alumina; it consists in agitating
recently precipitated alumina with the decoction of the dye.
_Yellow lakes_ are made with a decoction of Persian or French berries,
to which some potash or soda is added; into the mixture a solution of
alum is to be poured as long as any precipitate falls. The precipitate
must be filtered, washed, and formed into cakes, and dried. A lake may
be made in the same way with quercitron, taking the precaution to purify
the decoction of the dye-stuff with buttermilk or glue. After filtering
the lake it may be brightened with a solution of tin. Annotto lake is
formed by dissolving the dye-stuff in a weak alkaline lye, and adding
alum water to the solution. Solution of tin gives this lake a lemon
yellow cast; acids a reddish tint.
_Red lakes._--The finest of these is _carmine_.
This beautiful pigment was accidentally discovered by a Franciscan monk
at Pisa. He formed an extract of cochineal with salt of tartar, in order
to employ it as a medicine, and obtained, on the addition of an acid to
it, a fine red precipitate. Homberg published a process for preparing
it, in 1656. Carmine is the colouring matter of cochineal, prepared by
precipitation from a decoction of the drug. Its composition varies
according to the mode of making it. The ordinary carmine is prepared
with alum, and consists of _carminium_ (see COCHINEAL), a little animal
matter, alumina, and sulphuric acid. See CARMINE.
_Carminated lake_, called lake of Florence, Paris, or Vienna. For making
this pigment, the liquor is usually employed which is decanted from the
carmine process. Into this, newly precipitated alumina is put; the
mixture is stirred, and heated a little, but not too much. Whenever the
alumina has absorbed the colour, the mixture is allowed to settle, and
the liquor is drawn off.
Sometimes alum is dissolved in the decoction of cochineal, and potash is
then added, to throw down the alumina in combination with the colouring
matter; but in this way an indifferent pigment is obtained.
Occasionally, solution of tin is added, to brighten the dye.
A lake may be obtained from kermes, in the same way as from cochineal;
but now it is seldom had recourse to.
_Brazil-wood lakes._--Brazil wood is to be boiled in a proper quantity
of water for 15 minutes; then, alum and solution of tin being added, the
liquor is to be filtered, and a solution of potash poured in as long as
it occasions a precipitate. This is separated by the filter, washed in
pure water, mixed with a little gum water, and made into cakes. Or, the
Brazil wood may be boiled along with a little vinegar, the decoction
filtered, alum and salt of tin added, and then potash-lye poured in to
precipitate the lake. For 1 pound of Brazil wood, 30 to 40 pounds of
water, and from 1-1/2 to 2 pounds of alum, may be taken, in producing a
deep red lake; or, the same proportions with half a pound of solution of
tin. If the potash be added in excess, the tint will become violet.
Cream of tartar occasions a brownish cast.
_Madder lake._--A fine lake may be obtained from madder, by washing it
in cold water as long as it gives out colour; then sprinkling some
solution of tin over it, and setting it aside for some days. A gentle
heat may also be applied. The red liquor must be then separated by the
filter, and decomposed by the addition of carbonate of soda, when a fine
red precipitate will be obtained. Or, the reddish brown colouring matter
of a decoction of madder may be first separated by acetate of lead, and
then the rose-red colour with alum. Or, madder tied up in a bag is
boiled in water; to the decoction, alum is added, and then potash. The
precipitate should be washed with boiling water, till it ceases to tinge
it yellow; and it is then to be dried.
The following process merits a preference.
Diffuse 2 pounds of ground madder in 4 quarts of water, and after a
maceration of 10 minutes, strain and squeeze the grounds in a press.
Repeat this maceration, &c. twice upon the same portion of madder. It
will now have a fine rose colour. It must then be mixed with 5 or 6
pounds of water and half a pound of bruised alum, and heated upon a
water bath for 3 or 4 hours, with the addition of water, as it
evaporates, after which the whole must be thrown upon a filter cloth.
The liquor which passes is to be filtered through paper, and then
precipitated by carbonate of potash. If the potash be added in three
successive doses, three different lakes will be obtained, of
successively diminishing beauty. The precipitates must be washed till
the water comes off colourless.
_Blue lakes_ are hardly ever prepared, as indigo, prussian blue, cobalt
blue, and ultramarine, answer every purpose of blue pigments.
_Green lakes_ are made by a mixture of yellow lakes with blue pigments;
but chrome yellows mixed with blues produce almost all the requisite
shades of green.
LAMINABLE is said of a metal which may be extended by passing between
steel or hardened (chilled) cast-iron rollers.