MANUFACTURE OF GUM LAC BY THE LAC INSECT.
Another insect of the same family as the cochineal, prepares a substance
called gum lac, which is used as a dye, and also as a varnish. This is
the lac insect, (_coccus lacca_,) found on several kinds of trees in the
East Indies, especially in the uncultivated mountains on both sides the
Ganges, where it is produced in such abundance, that were the
consumption ten times greater than it is, the markets might be readily
supplied. So great is the accumulation of these insects on the trees
which they frequent, that the branches appear as if covered with red
dust, and their sap is so much exhausted, that they wither and produce
no fruit: the leaves also drop off, or turn to a blackish hue. The
insects fix themselves so close together, that it is supposed that not
more than one in six can have room to complete her cell. It is said they
are transplanted from place to place by birds, which cannot perch upon
the branches without carrying off a number to the next place they rest
upon.
The female, when about to lay her eggs, becomes completely glued to the
branch by a semi-pellucid liquid, which accumulates round the body, and
hardens by exposure to the air. This is the gum lac, the original use of
which is to form a cell for the young. When the eggs are laid, the
parent insect becomes a mere lifeless bag of an oval shape, containing a
small quantity of beautiful red liquid. On this liquid the young insects
feed as soon as they come to life; after which they pierce the cell, and
come forth one by one. Some small branches of _mimosa cinerea_, gathered
when the lac was in a very fresh looking state, became covered with
myriads of exceedingly minute animals at the end of fourteen days. They
issued from small holes over the surface of the cells, and when single
ran about pretty briskly; but in general they were so numerous as to be
crowded over one another. The cells themselves were very much like
amber; the outer portion was strong and resisting, but the partitions of
the interior were thinner, and formed irregular squares, pentagons, and
hexagons, having no communication with each other.
There are four sorts of lac known in commerce, but these are only so
many different preparations of the same substance. Stick lac is the lac
in its natural state, with much of the woody parts of the branches
adhering to it: this is collected in the East twice a year, the only
trouble being to break off the twigs and branches, and take them to the
nearest market, with the lac upon them; or, if destined for exportation,
the lac is separated from the larger branches for convenience of
freight.
Seed lac is the second description known in commerce. This is a
collection of granules, obtained from the former after the colouring
matter has been extracted by water, but this is seldom imported, being
manufactured into shell lac in India. Lump lac is the third form, being
merely the granules further purified and made into lumps. Lastly, there
is shell lac, in which the substance is purified to the utmost by being
put in bags and held over a fire until sufficiently melted to pass
through the pores of the linen. The bags are then pressed and squeezed
at the same time that they are passed over a smooth surface of wood,
thus depositing the lac in thin layers. The fineness and purity of the
lac will of course depend on the fineness of the bag through which it is
passed. Shell lac if pure will take fire when laid on a hot iron, and
will burn with a strong but not disagreeable smell. The heat of the
ship’s hold is very apt to run this commodity into a solid mass, in
which case its value is much depreciated.
The different kinds of lac are largely used by Indians for ornamental
purposes. Of the lump lac they make _bangles_, or armlets for women of
the lower class; shell lac being employed for the same kind of ornaments
for the upper classes, and also for beads, chains, necklaces, and other
adornments. They also make a good varnish by melting the lac, colouring
it with cinnabar or some other pigment, and making it into sticks like
our sealing wax. The box, cabinet, or other article about to be
varnished, is made hot by a charcoal fire, and then rubbed over with a
stick of lac, the surface being afterwards smoothed with a piece of
folded plantain leaf to make it equal. A similar varnish is often used
on images and ornamental figures. The religious houses of the Indians
are often adorned with very thin beaten lead, coloured with various
varnishes made from lac. The leaf of lead is laid upon a smooth heated
iron while the varnish is being applied.
Lac is also extensively used as a dye. By pouring warm water on stick
lac, a crimson solution is obtained, which is the source of much of the
value attached to lac. This colouring matter is extracted in various
ways, and made into small square cakes for sale; these go by the names
of lac dye, lac lake, or cake lake. When broken, the cakes are dark
coloured, shining, smooth and compact, and when scraped or powdered they
present a bright red colour approaching carmine. The native mode of
dyeing with this substance is described as follows. They take one gallon
of the red liquid, and add to it three ounces of alum. Three or four
ounces of tamarinds are boiled in a gallon of water and strained. Equal
parts of the red liquid and of the tamarind water are then mixed over a
brisk fire; and the pieces of silk or cotton cloth to be dyed are dipped
and wrung alternately, until they have received a proper proportion of
the dye. To deepen the colour they increase the proportion of the red
liquid, and lengthen the time during which the cloth remains immersed in
it. The colour is rendered permanent by the use of bark in the rinsing
water.
There is yet another and a singular employment of lac among the Indians.
The polishing grindstones used by eastern lapidaries are composed of a
mixture of three parts river sand with one part lac: these are mixed in
a vessel over the fire, and then formed into the shape of a grindstone;
the part of the lac being merely that of a cement to hold the sand
together.
In this country lac is valuable partly as a dye, partly as a varnish. As
a dye it is less beautiful, but more durable than cochineal. It forms
the best kinds of sealing wax, and is also used in the hat manufacture.
With regard to its use as a dyeing drug we find the following remarks in
the Entomology of Kirby and Spence. “It has been employed to impart a
blood red or crimson dye to cloth from the earliest ages, and was known
to the Phœnicians before the time of Moses, under the name of _Tola_ or
_Thola_, to the Greeks under that of _Coccus_, and to the Arabians and
Persians under that of _Kermes_ or _Alkermes_; whence, as Beckmann has
shown, and from the epithet _vermiculatum_ given to it in the middle
ages, when it was ascertained to be the produce of a worm, have sprung
up the Latin _coccineus_, the French _cramoisi_ and _vermeil_, and our
_crimson_ and _vermilion_. It was most probably with this substance that
the curtains of the tabernacle (Exodus xxvi.) were dyed deep red, (which
the word scarlet, as our translators have rendered it, then implied, not
the colour now so called, which was not known in James the First’s
reign, when the Bible was translated;)—it was with this that the
Grecians and Romans produced their crimson; and from the same source
were derived the imperishable reds of the Brussels and Flemish schools.
In short, previous to the discovery of cochineal, this was the material
universally used for dyeing the most brilliant red then known; and
though that production of the New World has, in some respects
undeservedly, supplanted it in Europe, where it is little attended to
except by the peasantry of the provinces in which it is found, it still
continues to be employed in great part of India and Persia.
Some other insects besides the cochineal and lac insects are found to
produce dyes. The galls of a peculiar species of aphis are used in the
Levant, Persia and China, for dyeing silk crimson, and it is thought
that the galls of another species of this insect, common on the fir
trees of this country, might be employed for a similar purpose. A
species of mite is employed in Guinea and Surinam as a dye, and it is
suggested that the beautiful little dazzling red mite which is common
here, might also yield a valuable tincture. Réaumur has even suggested
that water colours of beautiful tints not otherwise easily attainable,
might be procured by feeding the common clothes-moth on different
coloured wools. The excrement of this insect always retains the colour
of the substance forming the food, and mixes well with water to form a
pigment.
[Illustration:
NUT GALLS AND THE GALL INSECT.
]