_Antique marbles._--The most remarkable of these are the
following:--_Parian marble_, called _lychnites_ by the ancients, because
its quarries were worked by lamps; it has a yellowish-white colour; and
a texture composed of fine shining scales, lying in all directions. The
celebrated Arundelian tables at Oxford consist of Parian marble, as well
as the Medicean Venus. _Pentelic marble_, from Mount Penteles, near
Athens, resembles the Parian, but is somewhat denser and finer grained,
with occasional greenish zones, produced by greenish talc, whence it is
called by the Italians _Cipolino statuario_. The Parthenon, Propyleum,
the Hippodrome, and other principal monuments of Athens, were of
Pentelic marble; of which fine specimens may be seen among the Elgin
collection, in the British Museum. _Marmo Greco_, or Greek white marble,
is of a very lively snow white colour, rather harder than the preceding,
and susceptible of a very fine polish. It was obtained from several
islands of the Archipelago, as Scio, Samos, Lesbos, &c. _Translucent
white marble_, _Marmo statuario_ of the Italians, is very much like the
Parian, only not so opaque. Columns and altars of this marble exist in
Venice, and several towns of Lombardy; but the quarries are quite
unknown. _Flexible white marble_, of which five or six tables are
preserved in the house of Prince Borghese, at Rome. The _White marble of
Luni_, on the coast of Tuscany, was preferred by the Greek sculptors to
both the Parian and Pentelic. _White marble of Carrara_, between Specia
and Lucca, is of a fine white colour, but often traversed by gray veins,
so that it is difficult to procure moderately large pieces free from
them. It is not so apt to turn yellow as the Parian marble. This quarry
was worked by the ancients, having been opened in the time of Julius
Cæsar. Many antique statues remain of this marble. Its two principal
quarries at the present day are those of Pianello and Polvazzo. In the
centre of its blocks very limpid rock-crystals are sometimes found,
which are called Carrara diamonds. As the finest qualities are becoming
excessively rare, it has risen in price to about 3 guineas the cubic
foot. The _White marble_ of Mount Hymettus, in Greece, was not of a very
pure white, but inclined a little to gray. The statue of Meleager, in
the French Museum, is of this marble.
_Black antique marble_, the _Nero antico_ of the Italians. This is more
intensely black than any of our modern marbles; it is extremely scarce,
occurring only in sculptured pieces. The _red antique marble_, _Egyptum_
of the ancients, and _Rosso antico_ of the Italians, is a beautiful
marble of a deep blood-red colour, interspersed with white veins and
with very minute white dots, as if strewed over with grains of sand.
There is in the Grimani palace at Venice, a colossal statue of Marcus
Agrippa in _rosso antico_, which was formerly preserved in the Pantheon
at Rome. _Green antique marble_, _verde antico_, is a kind of breccia,
whose paste is a mixture of talc and limestone, while the dark green
fragments consist of serpentine. Very beautiful specimens of it are
preserved at Parma. The best quality has a grass-green paste, with black
spots of noble serpentine, but is never mingled with red spots. _Red
spotted green antique marble_, has a dark green ground marked with small
red and black spots, with fragments of _entrochi_ changed into white
marble. It is known only in small tablets. _Leek marble_; a rare variety
of that colour, of which there is a table in the Mint at Paris. _Marmo
verde pagliocco_ is of a yellowish green colour, and is found only in
the ruins of ancient Rome. _Cervelas marble_ of a deep red, with
numerous gray and white veins, is said to be found in Africa, and highly
esteemed in commerce. _Yellow antique marble_, _giallo antico_ of the
Italians; colour of the yolk of an egg, either uniform or marked with
black or deep yellow rings. It is rare, but may be replaced by Sienna
marble. _Red and white antique marbles_, found only among the ruins of
ancient Rome. _Grand antique_, a breccia marble, containing shells,
consists of large fragments of a black marble, traversed by veins or
lines of a shining white. There are four columns of it in the Museum at
Paris. _Antique Cipolino marble._ Cipolin is a name given to all such
marbles as have greenish zones produced by green talc; their fracture is
granular and shining, and displays here and there plates of talc.
_Purple antique breccia marble_, is very variable in the colour and size
of its spots. _Antique African breccia_, has a black ground, variegated
with large fragments of a grayish-white, deep red, or purplish wine
colour; and is one of the most beautiful marbles. _Rose-coloured antique
breccia_ marble is very scarce, occurring only in small tablets. There
are various other kinds of ancient breccias, which it would be tedious
to particularize.
_Modern marbles._--1. British. Black marble is found at Ashford,
Matlock, and Monsaldale in Derbyshire; black and white in the north part
of Devonshire; the variegated marbles of Devonshire are generally
reddish, brownish, and grayish, variously veined with white and yellow,
or the colours are often intimately blended; the marbles from Torbay and
Babbacombe, display a great variety in the mixture of their colours; the
Plymouth marble is either ash-coloured with black veins, or
blackish-gray and white, shaded with black veins; the cliffs near
Marychurch exhibit marble quarries not only of great extent, but of
superior beauty to any other in Devonshire, being either of a
dove-coloured ground with reddish-purple and yellow veins, or of a black
ground mottled with purplish globules. The green marble of Anglesea is
not unlike the _verde antico_; its colours being greenish-black,
leek-green, and sometimes dull purplish, irregularly blended with white.
The white part is limestone, the green shades proceed from serpentine
and asbestos. There are several fine varieties of marble in Derbyshire;
the mottled-gray in the neighbourhood of Moneyash, the light gray being
rendered extremely beautiful by the number of purple veins which spread
upon its polished surface in elegant irregular branches; but its chief
ornament is the multitude of _entrochi_, with which this transition
limestone-marble abounds. Much of the transition and carboniferous
limestone of Wales and Westmoreland is capable of being worked up into
agreeable dark marbles.
In Scotland, a particularly fine variety of white marble is found in
immense beds, at Assynt in Sutherlandshire. A beautiful ash-gray marble
of a very uniform grain, and susceptible of a fine polish, occurs on the
north side of the ferry of Ballachulish in Invernesshire. One of the
most beautiful varieties is that from the hill of Belephetrich in Tiree,
one of the Hebrides. Its colours are pale blood-red, light flesh-red,
and reddish-white, with dark green particles of hornblende, or rather
sahlite, diffused through the general base. The compact marble of Iona
is of a fine grain, a dull white colour, somewhat resembling pure
compact felspar. It is said by Bournon, to consist of an intimate
mixture of tremolite and carbonate of lime, sometimes with yellowish or
greenish-yellow spots. The carboniferous limestone of many of the coal
basins in the lowlands of Scotland may be worked into a tolerably good
marble for chimney-pieces.
In Ireland, the Kilkenny marble is the one best known, having a black
ground more or less varied with white marks produced by petrifactions.
The spar which occupies the place of the shells, sometimes assumes a
greenish-yellow colour. An exceedingly fine black marble has also been
raised at Crayleath in the county of Down. At Louthlougher, in the
county of Tipperary, a fine purple marble is found, which when polished
looks very beautiful. The county of Kerry affords several variegated
marbles, not unlike the Kilkenny.
France possesses a great many marble quarries which have been described
by Brard, and of which a copious abstract is given under the article
marble,--_Rees’ Cyclopedia_.
The territory of Genoa furnishes several beautiful varieties of marble,
the most remarkable of which is the _polzevera di Genoa_, called in
French the _vert d’Egypte_ and _vert de mer_. It is a mixture of
granular limestone with a talcose and serpentine substance disposed in
veins; and it is sometimes mixed with a reddish body. This marble was
formerly much employed in Italy, France, and England, for
chimney-pieces, but its sombre appearance has put it out of fashion.
Corsica possesses a good statuary marble of a fine close grain, and pure
milky whiteness, quarried at Ornofrio; it will bear comparison with that
of Carrara; also a gray marble (_bardiglio_), a cipolin, and some other
varieties. The island of Elba has immense quarries of a white marble
with blackish-green veins.
Among the innumerable varieties of Italian marbles, the following
deserve especial notice.
The _rovigio_, a white marble found at Padua; the white marble of St.
Julien, at Pisa, of which the cathedral and celebrated slanting tower
are built; the Biancone marble, white with a tinge of gray, quarried at
Magurega for altars and tombs. Near Mergozza the white saline marble
with gray veins is found, with which the cathedral of Milan is built.
The black marble of Bergamo is called _paragone_, from its black colour,
like touchstone; it has a pure intense tint, and is susceptible of a
fine polish. The pure black marble of Como is also much esteemed. The
_polveroso_ of Pistoya, is a black marble sprinkled with dots; and the
beautiful white marble with black spots, from the Lago Maggiore, has
been employed for decorating the interior of many churches in the
Milanese. The Margorre marble found in several parts of the Milanese, is
bluish veined with brown, and composes part of the dome of the cathedral
of Milan. The green marble of Florence owes its colour to a copious
admixture of steatite. Another green marble, called _verde di Prado_,
occurs in Tuscany, near the little town of Prado. It is marked with
spots of a deeper green than the rest, passing even into blackish-blue.
The beautiful Sienna marble, or _brocatello di Siena_, has a yellow
colour like the yolk of an egg, which is disposed in large irregular
spots, surrounded with veins of bluish-red, passing sometimes into
purple. At Montarenti, two leagues from Sienna, another yellow marble is
met with, which is traversed by black and purplish-black veins. The
Brema marble is yellow with white spots. The _mandelato_ of the Italians
is a light red marble with yellowish-white spots, found at Luggezzana,
in the Veronese. The red marble of Verona is of a red rather inclining
to yellow or hyacinth; a second variety of a dark red, composes the vast
amphitheatre of Verona. Another marble is found near Verona, with large
white spots in a reddish and greenish paste. Very fine columns have been
made of it. The _occhio di pavone_ is an Italian shell marble, in which
the shells form large orbicular spots, red, white, and bluish. A
madreporic marble known under the name of _pietra stellaria_, much
employed in Italy, is entirely composed of star madrepores, converted
into a gray and white substance, and is susceptible of an excellent
polish. The village of Bretonico, in the Veronese, furnishes a splendid
breccia marble, composed of yellow, steel-gray, and rose-coloured spots.
That of Bergamo consists of black and gray fragments in a greenish
cement. Florence marble, called also ruin and landscape marble, is an
indurated calcareous marl.
Sicily abounds in marbles, the most valuable of which is that called by
the English stone-cutters, Sicilian jasper; it is red with large stripes
like ribands, white, red, and sometimes green, which run zigzag with
pretty acute angles.
Among the Genoese marbles we may notice the highly esteemed variety
called _portor_, on account of the brilliant yellow veins in a deep
black ground. The most beautiful kind comes from Porto-Venese, and Louis
XIV. caused a great deal of it to be worked up for the decoration of
Versailles. It costs now two pounds per cubic foot.
_Of cutting and polishing marble._--The marble saw is a thin plate of
soft iron, continually supplied during its sawing motion, with water and
the sharpest sand. The sawing of moderate pieces is performed by hand,
but that of large slabs is most economically done by a proper mill.
The first substance used in the polishing process is the sharpest sand,
which must be worked with till the surface becomes perfectly flat. Then
a second, and even a third sand of increasing fineness is to be applied.
The next substance is emery of progressive degrees of fineness, after
which tripoli is employed; and the last polish is given with tin-putty.
The body with which the sand is rubbed upon the marble, is usually a
plate of iron; but for the subsequent process, a plate of lead is used
with fine sand and emery. The polishing rubbers are coarse linen cloths,
or bagging, wedged tight into an iron planing tool. In every step of the
operation, a constant trickling supply of water is required.
Visiters of Derby may have an opportunity of inspecting Brown’s
extensive machinery for cutting marble into many ornamental forms, which
has been well described in Rees’ Cyclopedia.
Sir James Jelf patented, in 1822, a combination of machinery for cutting
any description of parallel mouldings upon marble slabs, for ornamental
purposes; in which, tools, supplied with sand and water, are made to
traverse to and fro.
Mr. Tullock obtained a patent, in 1824, for improvements in machinery
for sawing and grooving marble; the power being applied by means of
toothed wheels bearing cranks, which gave the see-saw motion to the
cutting iron plates.
In November, 1829, Mr. Gibbs secured, by patent, an invention for
working ornamental devices in marble, by means of a travelling drill,
guided by a mould of wood, &c., in counter relief; and in April, 1833,
Mr. G. W. Wilds obtained a patent for machinery, which consists of a
series of circular cutters, for separating slabs from a block of marble;
the block being advanced slowly to meet the cutters, by the progressive
movement of a platform upon wheels, driven by the agency of a rack and
pinion, as in the cylinder boring machine of the steam-engine
manufacturer. Sand and water must be supplied, of course, from a hopper,
to these smooth cutting discs of iron or copper. See GLASS-CUTTING. He
proposes also to mould and polish marble, by applying a rotatory wheel
or cylinder of any shape to it, in its carrying frame.
MARCASITE, is a variety of iron pyrites, containing generally a little
arsenic.
MARGARATES, are saline compounds of margaric acid with the bases.
MARGARIC ACID, is one of the acid fats, produced by saponifying tallow
with alkaline matter, and decomposing the soap with dilute acid. The
term Margaric signifies PEARLY-looking.
The physical properties of the margaric and stearic acids are very
similar; the chief difference is that the former is more fusible,
melting at 140° F. The readiest mode of obtaining pure margaric acid, is
to dissolve olive oil soap in water, to pour into the solution, a
solution of neutral acetate of lead, to wash and dry the precipitate,
and then to remove its oleate of lead by ether, which does not affect
its margarate of lead. The residuum being decomposed by boiling hot
muriatic acid, affords margaric acid. When heated in a retort this acid
boils. It is insoluble in water, very soluble in alcohol and ether; it
reddens litmus paper, and decomposes with the aid of heat, the
carbonates of soda and potash.
MARINE ACID. See MURIATIC ACID.
MARINE SALT. See SALT.
MARL (_Marne_, Fr.; _Mergel_, Germ.), is a mixed earthy substance,
consisting of carbonate of lime, clay, and siliceous sand, in very
variable proportions; it is sometimes compact, sometimes pulverulent.
According to the predominance of one or other of these three main
ingredients, marls may be distributed into calcareous, clayey, and
sandy. See LIMESTONE.
MARQUETRY, is a peculiar kind of cabinet work, in which the surface of
wood is ornamented with inlaid pieces of various colours and forms. The
_marqueteur_ puts gold, silver, copper, tortoise-shell, mother-of-pearl,
ivory, horn, &c. under contribution. These substances being reduced to
laminæ of proper thinness, are cut out into the desired forms by
punches, which produce at once the full pattern or mould, and the empty
one, which enclosed it; and both serve their separate purposes in
marquetry. For the methods of dyeing the woods, &c. see IVORY.
MARTIAL, signifies belonging to iron; from Mars, the mythological name
of this metal.
MASSICOT, is the yellow oxide of lead.
MASTIC (Eng. and Fr.; _Mastix_, Germ.), is a resin produced by making
incisions in the _Pistacia Lentiscus_, a tree cultivated in the Levant,
and chiefly in the island of Chios. It comes to us in yellow, brittle,
transparent, rounded tears; which soften between the teeth; with
bitterish taste and aromatic smell, and a specific gravity of 1·07.
Mastic consists of two resins; one soluble in dilute alcohol; but both
dissolve in strong alcohol. Its solution in spirit of wine constitutes a
good varnish. It dissolves also in oil of turpentine. See VARNISH.
MATRASS, is a bottle with a thin egg-shaped bottom, much used for
digestions in chemical researches.
MATTE, is a crude black copper reduced, but not refined from sulphur and
other heterogeneous substances.
MEADOW ORE, is conchoidal bog iron ore.
MEDALS. For their composition, see BRONZE and COPPER.
MEERSCHAUM (Germ.; _sea-froth_, Eng.; _Ecume de Mer_, _Magnésie
carbonatée silicifère_, Fr.), is a white mineral, of a somewhat earthy
appearance, always soft, but dry to the touch, and adhering to the
tongue. Specific gravity, 2·6 to 3·4; affords water by calcination;
fuses with difficulty at the blowpipe into a white enamel; and is acted
upon by acids. It consists, according to Klaproth, of silica, 41·5;
magnesia, 18·25; water and carbonic acid, 39. Other analysts give,
silica 50, magnesia 25, water 25. It occurs in veins or kidney-shaped
nodules, among rocks of serpentine, at Egribos, in the island of
Negropont, Eski-Schehir in Anatolia, Brussa at the foot of Mount
Olympus, at Baldissero in Piedmont, in the serpentine veins of Cornwall,
&c.
When first dug up, it is soft, greasy, and lathers like soap; and is on
that account used by the Tartars in washing their linen. The well-known
Turkey tobacco-pipes are made from it, by a process analogous to that
for making pottery ware. The bowls of the pipes, when imported into
Germany, are prepared for sale by soaking them first in tallow, then in
wax, and finally by polishing them with shave-grass.
MELLITE. (Eng. and Fr.; _Honigstein_, Germ.) See HONEYSTONE.
MELLITIC ACID, which is associated with alumina in the preceding
mineral, crystallizes in small colourless needles, is without smell, of
a strongly acid taste, permanent in the air, soluble in water and
alcohol, as also in boiling hot concentrated sulphuric acid, but is
decomposed by hot nitric acid, and consists of 50·21 carbon, and 49·79
oxygen. It is carbonized at a red heat, without the production of any
inflammable oil.
MELLON, is a new compound of carbon and azote, discovered by M. Liebig,
by heating bi-sulpho-cyanide of mercury. The mellon remains at the
bottom of the retort under the form of a yellow powder.
MENACHANITE, an ore of _titanium_, found in the bed of a rivulet which
flows into the valley Menacan, in Cornwall.
MERCURY or QUICKSILVER. This metal is distinguished by its fluidity at
common temperatures; its density = 13·6; its silver blue lustre; and its
extreme mobility. A cold of 39° below zero of Fahrenheit, or -40° cent.,
is required for its congelation, in which state its density is increased
in the proportion of 10 to 9, or it becomes of spec. grav. 15·0. At a
temperature of 656° F. it boils and distils off in an elastic vapour;
which, being condensed by cold, forms purified mercury.
Mercury combines with great readiness with certain metals, as gold,
silver, zinc, tin, and bismuth, forming, in certain proportions, fluid
solutions of these metals. Such mercurial alloys are called _amalgams_.
This property is extensively employed in many arts; as in extracting
gold and silver from their ores; in gilding, plating, making
looking-glasses, &c. Humboldt estimates at 16,000 quintals, of 100 lbs.
each, the quantity of mercury annually employed at his visit to America,
in the treatment of the mines of New Spain; three-fourths of which came
from European mines.