Silk is the production of a species of Moth, called the _Phalæna
mori_ or Mulberry moth, and its original locality, as we have already
stated, appears to have been China or Persia. The changes that
butterflies or moths undergo, having already been described at page
212 of Vol. II., it will be needless to repeat them. The substance
which the animal spins to protect itself when in the Pupa state, is
the silk, which, before it is dyed or bleached, is of a bright yellow
colour more or less inclining to orange. The Silk-worm in not the
only creature that produces substances of this description, for many
other kinds of butterflies and moths do the same; a kind of silk has
also been manufactured from the webs of spiders, and as they require
less attention than the Silk-worms, the plan might have answered,
had it not been for the ravenous appetites of the little spinners,
who, when brought together in any quantity very speedily devour each
other. Certain shell-fish also produce a kind of silky thread; as, for
instance, the muscle, but more particularly the _pinna_, a large kind
of shell-fish found in the Mediterranean and other seas.
The time that elapses while the silk-worm is undergoing its changes,
varies according to the warmth of the weather, and the quantity of
nourishment with which it is supplied; the Chinese, who are very
particular on this head, take the greatest pains to supply the little
creature with food, as on this they say depends the quantity of silk
which the worm will produce. They calculate that the same number of
insects, which would, if they had attained their full size, in from
twenty-three to twenty-five days, produce twenty-five ounces of silk,
would only yield twenty ounces if their growth occupied twenty-eight
days, and only ten ounces if forty days. During the first twenty-four
hours of the creature's existence, the patient Chinese feeds the
objects of his care forty-eight times, or once every half hour, and
during the second day and night thirty times, and so on, reducing the
number of meals as the worms grow older; the care bestowed on their
culture, and the numerous precautions taken to preserve them clean and
warm, are curiously expressed in the following extract from on old
Chinese work on the subject.
"The place where their habitation is built must be retired, free
from noisome smells, cattle and all noises; a noisome smell, or
the least fright, make great impressions upon so tender a breed;
even the barking of dogs and the crowing of cocks are capable of
putting them in disorder, when they are newly hatched.
"For the purpose of paying them every attention, an affectionate
mother is provided for the worms, who is careful to supply their
wants; she is called _Isan-mon_, mother of the worms. She takes
possession of the chamber, but not till she has washed herself
and put on clean clothes, which have not the least ill smell;
she must not have eaten any thing immediately before, or have
handled any wild succory, the smell of which is very prejudicial
to these tender creatures; she must be clothed in a plain habit,
without any lining, that she may be more sensible of the warmth
of the place, and accordingly increase or lessen the fire, but
she must carefully avoid making a smoke or raising a dust, which
would be very offensive to these tender creatures, which must be
carefully humoured before the first time of casting their slough.
Every day is to them a year, and has in a manner the four seasons;
the morning is the spring, the middle of the day the summer, the
evening the autumn, and the night the winter."
While it remains in the state of a caterpillar, the Silk-worm changes
its coat four times, and previous to each moult refuses its food, and
appears in a very sickly condition. As soon as its nest or cocoon is
finished, and it has changed into the pupa-state, the cocoons are
carefully removed from the place where the animal had formed them; and
after those which it is intended to keep, that they may perfect their
changes and lay eggs for the ensuing year, are removed, the remainder
are placed in large vessels, each covered with a thick blanket; they
are then exposed to heat sufficiently powerful to destroy the life
of the pupæ. This is generally accomplished by placing the vessels in
an oven, heated to about the same degree as that of a baker after his
loaves are drawn; here they are suffered to remain for about an hour,
they are then withdrawn, but the blanket that covers them, is not
removed for the space of five or six hours.
The first process in preparing the silk, is winding it off the cocoons:
for this purpose, after the rough outsides are removed, several
handfuls at a time are thrown into a vessel containing water, and
placed over a gentle fire, the water is then allowed to be heated to
nearly the boiling point; a short stunted brush formed of heath or any
other shrub of that description, is now gently moved about among the
cocoons, and on withdrawing it from the water, the ends of the silk are
found to have adhered to it in several places; the winder then gathers
together with her fingers, as many ends as she intends the first
description of thread to consist of, and hands them to an assistant,
whose office it is to turn the reel as soon as the silk is laid upon
it; the principal workwoman, in the mean time, continually adds to the
thread the ends of fresh cocoons, as soon as the first are exhausted.
The silk, when reeled off in this manner, is called _singles_, and is
used in weaving to form the _weft_, that is, the thread that crosses
the cloth from side to side. Another description of silk threads, are
called trams, and these consist of two or three _singles_ twisted
together; but the strongest and most valuable sort is the _organzine_,
which is formed by placing skeins of _singles_ upon a reel, and
as they are wound off, they are, by the assistance of machinery,
strongly twisted. Two or three of these are then taken, and the whole
again twisted together to form a stronger thread; this thread is the
_organzine_, and is used for the warp or length of the cloth.
The process of making organzine, is called _throwing_, and the
throwsters form a very important branch of the silk business. Before
the year 1719, the whole of the thrown silk used in England came from
abroad, but at that time Sir Thomas Lombe and his brother erected a
large mill at Derby for the purpose of forming organzine, and obtained
an exclusive patent for its manufacture, for the term of fourteen
years; at the expiration of that term, they applied for a renewal of
their patent, but it was refused by Parliament, and the trade has since
then been open to competition. Some idea may be formed of the extent to
which the silk manufacture is carried on at present in England, by the
fact that no less a quantity than four million, six hundred and ninety
three thousand, five hundred and seventeen pounds of raw silk were
imported for home consumption, in the year ending January 1831.
The substance on which this valuable caterpillar feeds, is the leaf
of the Mulberry Tree; and Providence as if to ensure the continuance
of this useful species, has so ordained it, that no other insect will
partake of the same food; thus ensuring a certain supply for the little
spinster.
* * * * *
The engravings which illustrate this article are copied from original
Chinese drawings: the first shows the apartment in which the worms
are fed, and the manner in which the little trays containing them are
arranged. In the second, the cocoons being completed by the insect, are
being cleared of dirt and dead leaves, before they are removed from the
frames on which they had spun. The third represents the winding off
the silk into _singles_, but the windster appears for the moment to
have left her post for the purpose of blowing the fire. In the fourth
engraving, a Chinese silk-loom, is shown; the figure seated above,
among the machinery, appears to assist the labour by means of her
weight.
[Illustration: WINDING THE SILK FROM THE COCOONS.]
[Illustration: CHINESE MODE OF WEAVING THE SILK]