Francis Lieber.

Library of universal knowledge. A reprint of the last (1880) Edinburgh and London edition of Chambers' encyclopaedia, with copious additions by American editors (Volume 13) online

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the agreement of 1537, to certain portions of Silesia; and without declaring war, marched
into and took possession of the province, maintaining his hold despite the utmost efforts
of Austria in 1740-42, and 1711-15, called the Jirst and second Silesian wars. After the
third Silesian war, better known as the seven years' war (q.v.), it was finally ceded (1763)
to Prussia.

SILESIA, AUSTRIAN, a duchy and crown-land of the Austrian empire, bounded on the
n.e. by Prussia, and on the s.w. by Moravia. Area, 1980 sq.m. ; pop. '76, 558,196. It
is mountainous in the w., where the Spieglitzer Schneeberge, a summit of the Sudetic
chain, rises to the height of 4,512 feet. The crown-land comprises 1806 sq.m. of level
laud, of which by far the greater portion is arable or under wood. The climate, though
rough, is healthy, and the soil produces good crops of rye, oats, barley, flax, etc.
Within the crown-land rise the Oder and Vistula. Cattle-breeding and bee-keeping are
important branches of industry; 110,000 head of sheep belong to the crown-laud. Iron,
lead, and coal mining are profitably pursued. The manufactures are principally spir-
its, copper and iron wares, and liueu and cotton fabrics.

SI'LEX (Lat. flint), a generic name given by some mineralogists to all those minerals
of which silica is the principal ingredient. See QUARTZ.

SIL'HOTJETTE, the name given to a profile or shadow-outline of the human figure,
filled in of a dark color, the shadows and extreme depths being sometimes indicated by
the heightening effect of gum or some other shining material. This species of design
was known among the ancients, and was by them carried to a high degree of perfection,
as the monochromes on Etruscan vases amply testify; but the name silhouette is quite
modern, dating from about the middle of last century. It was taken from Etienne
de Silhouette, the French minister of finance in 1759, 'who, to replenish the treasury,
exhausted by the costly wars with Britain and Prussia, and by excessive prodigalities,
inaugurated numerous reforms, and the strictest economy of expenditure. His extreme
parsimony in all finance matters made him a choice subject for caricature; so that any
mode or fashion that was plain and cheap " surtouts" without plaits, trousers with-
out pockets was. styled d la silhouette; and profiles made by tracing the shadow^ pro-
jected by the light of a candle on a sheet of white paper being then much in vogue,
have continued to bear the name. Although without merit as a work of art, the sil-
houette presents a clear and welKmarked profile, and such instruments as the panto-
graph (q.v.), etc., used to be frequently employed to obtain profiles of a reduced size
direct from the humtln features. Profiles cut out of black paper with scissors also
receive the name of silhouettes


SILICON, or SILI'CIUM (sym. Si. eq. 14 in new system, 28 spec. grav. 2.49), is one
of the non-metallic elements (see CHEMISTRY), it may be obtained in first of these, the
three different forms, viz., the amorphous, the graphitoid, and the crystalline. It is the
amorphous silicon, which is obtained by the processes in common use, the second and
third being obtained from this first modification.

Amorphous silicon presents the appearance of a dull brown powder, which adheres
to the finger, is insoluble in water and in nitric and sulphuric acids, but readily soluble
in hydrofluoric acid, and in a hot solution of potash. It is a non-conductor of elec-
tricity, and when heated in air or oxygen its external surface burns brilliantly, and is
converted into silica, which fuses from the extreme heat, and forms a coating over the
unburned silicon. Oraphitoid silicon is obtained by exposing the amorphous variety to
an intense heat in a closed platinum crucible. This forui of silicon will not take fire
when heated in oxygen gas, and resists the solvent action of pure hydrofluoric acid,
although it rapidly dissolves in a mixture of nitric and hydrofluoric acids ; moreover,
as another point of difference, it is a conductor of electricity. For the description of
crystalled silicon, we may refer to a treatise by Deville (in the Ann. de Chimie, 3d
ser. vol. 49, p. 65), who obtained it in regular double six-sided pyramids of a dark
steel-gray color.

Silicon, in a state of combination with oxygen, is the most abundant solid constit-
uent of our globe; and, in less proportion, is an equally necessary ingredient of the
vegetable kingdom, while in the animal kingdom it occurs in mere 'traces, except in ft


few special cases. It is never found in nature except in combination with oxygen; but
by a somewhat difficult process which we need uot here describe it may be separated
as a dark brown powder. It was first isolated byBerzelius in 1823. For our knowledge
of the other modifications we are indebted to Wohler and Deville.

Silicon forms two oxides, one of which is only known in the hydrated state, while
the other is the well-known compound silica or silicic acid. Hydrated oxide of silicon is
represented by the formula 2HO,3SiO, and silicic acid by 8iO 2 . The hydrated oxide
exhibits many interesting chemical properties, but is of no practical importance.

Silicic acid or silica exists both in the crystalline and in the amorphous form. The
best examples of the crystalline form are rock-crystal, quartz, chalcedony, flint, sand-
stone, and quartzose sand. Silica in this form has 'a specific gravity of about 2.9, and is
only attacked with difficulty by potash or hydrofluoric acid. The amorphous form
exists naturally in opal, and is obtained artificially as gelatinous silica, etc. ; it differs
from the former in its specific gravity, being about 2.2, and in its being rapidly dissolved
by potash and by hydrofluoric acid. Pure silica (as it occurs in rock-crystal, for exam-
ple^ is perfectly transparent and colorless, and is sufficiently hard to scratch glass. The
heat of the oxyhydrogen blowpipe is required for its fusion, when it melts into a trans-
parent glass, capable of being drawn out into elastic threads. Perfectly pure silica in
its amorphous form may be obtained by various chemical processes. If a solution of
silicate of potash or soda be treated with hydrochloric acid, the silicic acid separates as a
hydrate, and on evaporating this to dryness, and treating it with boiling water, silicic
acid remains as an amorphous powder, which, after being washed, dried, and exposed
to a red heat, may be regarded as chemically pure. The hydrated silicic acid men-
tioned in the above experiment is soluble in water and (more freely) in acids and alka-
lies. The solubility of hydrated silicic acid in water accounts for the presence of silicic
acid in mineral springs, and m the Geysers of Iceland, as well as for its gradual separa-
tion from these waters in the form of petrifactions. That silica or silicic acid is a true
acid (although a feeble one) is obvious from its uniting with bases, especially those
which are capable of undergoing fusion, and forming true salts, known as silicates.
These silicates occur abundantly in nature; all the forms of clay, feldspar, mica, horn-
blende, augite, serpentine, etc., being compounds of this description. Silicic acid
combines with bases in various proportions. The following table, borrowed from Mil-
ler's Elements of Chemistry, vol. ii., shows the combinations which are of the most
usual occurrence:

Examples. Formulae.

or <?P<5miiilipftt* J Silicate of lime 2CaO,3SiO 2 .

,, or Sesquisihcates. -j Mcerschaum (hydrated silicate of magnesia) 2MgO,3SiO 2 -f 2HO.
Wollastonite (silicate of' lime) CaO, SiO 2 .

MO,SiO.,, Neutral silicates.

2MO,SiO 2 , Dibasic silicates.
MO,2SiO 2 , Bisilicates.

Bioptase (hydrated silicate of copper) CuO,SiO 2 -f- HO.

Olivine 2(Mg.Fe)O,SiO a .

Iron forge cinder ... 2FeO,SiO 2 .

The composition of many of the ordinary varieties of glass may be
approximately represented by mixtures of different silicates which
have this formula.

In the above formulas MO stands for 1 equivalent of any metallic protoxide, such aa
lime, magnesia, or protoxide of iron.

The following are the general characters of the silicates: Most of them are fusible,
the basic silicates fusing more readily than those which are either neutral or contain an
excess of acid. Excepting the silicates of the alkalies r.o silicates are soluble in water.
The anhydrous, neutral, and acid silicates of the earths resist'rhe action of all acida
except the hydrofluoric.

In conclusion we may remark that silica derives its name from silfx, flint, of which
it is the essential constituent, and that it is largely employed in the manufacture of glass,
china, and porcelain. For these purposes it is obtained in a finely comminuted state by
heating flints or portions of colorless quartz to redness, and plunging them in cold water.
The silica splits up into a friable mass, which may be easily ground to a fine powder.
The use of silica in giving firmness and rigidity to various parts of the animal organs is
exemplified in its free occurrence in the quill-part of the feather of birds, in the shields
of certain infusoria, and in the spicula occurring in sponges; while its similar use in the
vegetable kingdom is seen in its more or less abundant presence in the stalks of the
grasses, more particularly in the cereals and in the bamboo (where it is especially depos-
ited about the joints, and is known as tubasbeer), in the equisetae, etc.

Silicon may be made to combine with several other elements besides oxygen, but,
with the exception of silicofluoric acid, these compounds are of no practical value
Thus silicon and hydrogen form a hydride of silicon, a colorLss and spontaneously
inflammable gas. .Nitride of silicon is a bluish fibrous body, while sulphide of silicon is
a white earthy powder. Silicon unites with chlorine, bromine, and probably iodine and
fluorine, in two proportions corresponding to its oxygen compounds. Fluoride of silicon.
(SiFa) is a colorless pungent gas, liquefiable under strong pressure, and solidifying at
220, inflammable, and a non-supporter of combustion. It is obtained by heating
powdered glass with 12 times its weight of oil of vitriol, and when a stream of this gas is
transmitted through water a reaction takes place; two atoms of water and three atoms
of the fluoride of silicon yielding silicofluoric acid (HF, SiF), which remains in solution,


and silicon, which is deposited. A saturated solution of this acid forms a very sour
fuming liquid, which does not directly attack glass, but if allowed to evaporate on it,
causes erosion from the fluoride of silicon becoming evaporized, and free hydrofluoric
acid being left. A dilute solution is frequently employed in the laboratory as a precipi-
tant of potash, which it throws down in a transparent gelatinous form. With salts of
baryta it gives a white crystalline precipitate. It combines with bases to form salts,
none of which are of any special importance.

SILIQTJE, Siliqva, in botany, the fruit of the cruciferce, a capsule opening by two,
.valves, which, when ripe, separate from the base upward, leaving a central frame
(replum), to which the seeds remain attached, and which is regarded as formed by
parietal placentas, the valves giving way close to the suture. The seeds are either in
one row or two. A SILICULE (silieula) is merely a silique of a different form, the true
silique being long and narrow, the silicule broad and short, although LinnaBus made
this difference the foundation of the orders (siliquosa and xiiiculosa) of his class tetrady-
nami't, a distinction not now equally attended to in the subdivision of the natural order

SILISTRIA, a t. of the new principality of Bulgaria, is situated on the right bank of
the Danube, which is here nearly one-fourth of a mile wide, and is studded with numer-
ous islands. The houses are mean, and built generally of wood, though sometimes of
stone, and also of mud; the streets, like those of most Moslem cities, are crooked, nar-
row, dirty, and ill-paved; and the manufactures are insignificant, though there is a con-
siderable trade in wood and cattle. Pop. 20,000. The Dobrudscha, ceded by Turkey
to Rumania in 1873, is bounded by a line running from a point just e. of Silistria to
Manga lia on the coast. The importance of Silistria lay formerly in its value as a mili-
tary outpost of Turkey. Its walla were constructed of solid masonry, but consisted
merely of a fortified enceinte (q.v.) surrounded by a ditch, ^he great strength of the for-
tress depending upon the support given to it by detached works. Silistria is a town of
great antiquity, and wa^ a fortress under the Byz unities. Here, in 971, the By/antine
emperor. John Zimisces, routed the Itasuiaus under Sviatoslav. It has been repeatedly
assaulted and taken by the Russians. In 1849 Silistria was made a stronghold of the
first class, and was rendered almost impregnable by tho addition (1853) of 12 det.iched
forts on the s. and ea>t. On the outbreak of the Crimean war the Russians laid siego
to it, with an army of from 60,030 to 8J,000 men, but were compelled to retreat after 89
days. The congress of Berlin in 1873, when erecting Bulgaria into a principality,
dscraed that the fortifications of Silistria, like those of the other Bulgarian cities, should
be dismantled.

SILK AND SILK-WORM. The name silk is derived by the not unusual substitution of
I for r, from L-it. sericitin (Gr. serikon), so called as coming from the country of the Seres
or Chinese. The SILK-WORM is the caterpillar of the SlLK-WORM MOTFI, of which thero

body is thick and hairy
the wings are large and broad, either extended horizontally when at rest, or inclined
like the sides of a roof; the antennae are pectinated. The caterpillars feed on the leaves
and other tender parts of trees or other plants; the chrysalids are inclosed in a cocoon of
silk, which gives to some of the spacies a great economical importance. The most
important is the COMMON SILK-WORM (bomtyx mori), a native of the northern provinces
of China. Tlie perfect insect is about an inch in length, the female rather larger than
the male; the wings meeting like the sides of a roof; the color whitish, with a broad
pale brown b:ir across the upper wings. The females generally die very soon after they
have laid tliL-ir eggs, and the males do not survive much longer. The eggs are numerous,
about the size of a pin's head, not attached together, but fastened to the surface on which
they are laid by a gummy substance, which, when dry, becomes silky. They are laid
in the end of summer, and are hatched in the beginning of next summer. The caterpillar
is at first very small, not more than a quarter of an inch in lensrth, but rapidly increases
in size, till, when full grown, it is nearly 3 in. long. It is of a yellowish gray color.
The head is large. On the upper part of the last joint of the body is a horn-like process.
The skin is changed four or five times during the .growth of the caterpillar. Before
each change of skin, it becomes lethargic, and ceases to eat, whereas at other times it is
very voracious. When the skin is ready to be cast off, it bursts at the forepart, and
the caterpillar then, by continually writhing its body, without moving from the spot,
thrusts it backward; but silk-worms frequently die during the change of skin. A very
rapid increase of size takes place while the new skin is still soft. The natural food of
the silk-worm is the leaves of the white mulberry, but it will also feed on the leaves of
some other plants, as the black mulberry and the lettuce. When so fed. however, it
produces silk of inferior quality. The silk-producing organs are two large glands
(sericteria) containing a viscid substance, which extend along a great part of the^body,
and terminate in two sjnnnerets in the mouth. These glands become verv large when,
the change to the chrysalis or pupa state is about to take place. When abo'ut to spin its
cocoon, fche silk-worm ceases to eat, and first produces the loose rough fiber which forms
U. K. XIII. -33


the outer part of the cocoon, and then the more closely disposed and valuable fiber of its
interior. In this process, the position of the hinder part of the body is little changed,
but the head is moved from one point to another; and the cocoon when finished is much
shorter than the body, which, however, being benl, is completely inclosed in it. The
cocoon is about the size of a pigeon's egg. Eacli fiber of silk, when examined by a
microscope, is seen to be double, being equally derived from the two -silk-producing
organs of the caterpillar. A single liber often exceeds 1100 ft. in length. The time of
the silk-worm's life in the caterpillar state is generally about eight weeks. About fiv
days are occupied in the spinning of the cocoon ; after which about two or three weeki
elapse before the cocoon bursts and the perfect insect comes forth. The natural hurst-
ing of the cocoon is, however, injurious to the silk, and the silk-worm rearer prevents
it by throwing all the cocoons into boiling water, except those which he intends to keep
in order to the maintenance and increase of his stock. These he selects with care, so
that he may have about an equal number of male and female insects, the females being
known, even in the chrysalis state, by their larger size. The cocoons intended for the
production of moths are placed on a cloth in a somewhat darkened room, of which the
temperature is near, but does not exceed, 73 Fahr. ; and the moths, when produced, show-
no inclination to fly away, but remain on the cloth, lay their eggs, and die there. It is
an interesting peculiarity of this valuable species of moth, that neither in the caterpillar
nor in the winged state does it show that restless disposition which belongs to many
others, the caterpillars remaining contentedly in the trays or boxes in which ihey are
placed, feeding on the leaves with which they are there supplied, and at last only seek-
ing a proper place to assume the chrysalis form on small bundles of twigs which are
placed for that purpose above the trays; the perfect moths, in like manner, abiding
almost in one spot, and scarcely caring to use their wings. Owing to this peculiarity it
IB capable of being reared and managed in a way which would otherwise be impossible.

The silk-worm is liable to various diseases, particularly to one by which great num-
bers are often destroyed, and which is either caused or characterized by the growth of
a small fungus known -AS silk-worm-rot, or muscardiiw (q.v.).

Of the other species of silk-worm, many are rapidly increasing in commercial impor-
tance. The following is an enumeration of the chief silk-producing insects; those in
italics are not as yet employed in manufactures:

Bombyx mori. The common silk-worm, native of India, and reared in other parts of the

B. craesi. Crosses have been obtained between this and B. mori, yielding excellent silk,

at Mussooree.

B. textor. Native of Mussooree.
B. sinenxis, China.

B. Huttoni. Silk collected in Mussooree.
. Hortfieldi. Native of Java.

Attacus atlas. Native of India, and said to yield some of the " Tusseh silk."

A. Guerini. Native of Bengal.

A. ritini. Native of Assam.

A. cynthia. The "Eria," or "Arrindy" silk-worm, native of India, now extensively
raised in Hong-kong, Nepaul, Mussooree, Java, and to some extent in southern
Europe. It feeds on the leaves of the ailanto (q v.) tree.

Anthersea Mezankooria. The Mezankooria silk-moth.

A. Paphia. The true tusseh or tussur moth, native of Darjeeling, and other parts of
upper India. It is produced very extensively, and is chiefly collected in the jungle
districts by the Sahars and other half-wild castes who live in the jungles. The
cocoons are so carefully concealed in the leaves that much care is required to discover
them, the only indication being the dung of the caterpillar under the trees. The tus-
seh silk is easily wound off from the cocoons in the same way as that of the common

A. Assama. The Moonga, or Moogha, native of Assam.

A. Pernyi. North China.

A. Perrottetti. North China.

A. Roylci. Mussooree.

A. He'feri. Darjeeling.

A. Jana. Java.

A. Frit/iii. Darjeeling.

A. Liirism. Java.

The preceding seven are all called tusseh moths.

Actias Selene. Darjeeling.

Satttrnia pyrctrum. China.

S. Grotei. Darjeeling.

Jj(Kpn, Katinka, Java.

Neorix Jhittoni. Mussooree.

Caligula Tibeta. Mussooree.

C. Simla.

Solatia Lola. South-east Himalaya.
Cricula triferrentrata. Java.


It will be seen by the above list that hitherto very few of the silk-moths have been turned
to man's profit. The tirsl in importance after the common silk-worm is the true ttisse/i,
next the moouga, the silk from both of which can be wound off the cocoon; aud then
the eriu, which cannot be wound easily, and is therefore generally carded.

Silk appears not to have been well known to the ancients; although several times
mentioned in the translations of the Bible, the best authorities deny that it is in the original,
or that it was known to the Hebrews. Among the Greeks. Aristotle is the first who
mentions it, and he only says that " Pamphile, daughter of Plates, is reporfed to have fhvt
woven it in Cos;" and from all the evidence which has been collected, it would appear
that the natives of Cos received it indirectly (through the Pheuiciuns and Persians) from
China. The silken webs of Cos found their way to Rome, but it was very long before
they were obtainable except by the most wealthy. The cultivation in Europe of the
worm itself did not take place until 530 A.D. , when, according to an account given by
Proccpiud, the eggs were brought from India (China) to the emperor Justinian by some

In China the cultivation of silk is of the highest antiquity, and according to the
greatest Chinese authorities, it was first begun l:y Si-ling, the wife of the emperor
Hoaiig-ti, 2,600 years B.C., and the mulberry was cultivated for the purpose of feeding
them only 40 years later.

Since its introduction into Europe it has always formed a great branch of industry
in Italy, r lurkey, and Greece, and it has been cultivated to some extent in France, Spain,
and Portugal. In England, too, from time to time, laudable efforts have been made to
cultivate it, especially by Mrs. Whitby cf ^ewlands. Mr. Mason of Yatelyiu Hampshire,
and lady Dorothy Neville of Dangsteiu in Lampshire; but their partial success has
not encouraged others to pursue this branch of industry, ^hieh requires a warmer and
less variable climate r.r.d cheaper labor than we can command.

The quantity of silk raised in the world is enoimous. Great Britain imports annu-
ally in the unmanufactured state: " Kaw" silk, about 6.5CO.OCO Ibs. ; " waste," or knubs
and husks, about 3.500,OCO Ibs. ; besides undyed " singles," about 5,700 Ibs. ; tram, about
7,000 Ibs.; orgauziue. about 9,000 Ibs.; and dyed singles and tram, about 3.CCO Ibs.
org-inzine, about 10,000 Ibs. Singles, tram, and organzine are terms applied to the
thread af I er it has undergone certain t pern i ions (to be afterward desciibeo). The total
quantity is thus about 10^,OCO,000 Ibs., cf the value of 5,000,1(0; and in addition to this
We import manufactured silk goods to the value of about 12,500.000; so that the impor-
tance of this little in-ect to Great Britain alone is represented annually by about 17,500,-
000. It requires 1600 worms to raise a pound of silk.

Rearing of &i'k-ir<> nns. It b <.f the 1 rst consequence in the production of silk that
one of the species of mulberry ?! ould 1 e cultivated, rnd that it should be so favorably
situated as to climate that its foliage is in readiness for itedirg the young worms when
they are first hatched from the eggs. The species best adapted is tie wbite, erry,
morn* dibit. The extreme lateness of season at which ihe black mulbe;ry jModuces its
leaves prevents its employment generally, besides which it \\ill not bear the loss of its
leaves so well. It is said that in some parts of China the silk-worm is easily reared upon
the trec> in the open air. So IKtle has it a tendency to wander far from the place of its
birth, if food be at hand, that it cnly requires a warm, dry atmosphere to bring it to per-
fection: but usually, even in China, and in all other countries, it is thought desirable
to raise the silk-worm in properly rrranged luildings, and to supply it with mulberry
leaves gathered from day to day. In India, China, and other tropical countries, the

Online LibraryFrancis LieberLibrary of universal knowledge. A reprint of the last (1880) Edinburgh and London edition of Chambers' encyclopaedia, with copious additions by American editors (Volume 13) → online text (page 115 of 203)