The national era. [volume] (Washington [D.C.]) 1847-1860, 1853-06-02

tlhstlC, anu stnhi-d anu ~ 'h"0 hN''N
for the doors OF stoves and other purposes, as a
substitute for glass. In some parts If Russia 1t
is much used for the windows of houses, where
it is known by the name of Muscoyy & Ass. 1t
is frequently called isinglass.
Nos. 6 and 7.-GRANITE is composed OF
quartz, felspar, and mica-the latter thrown
about in every possible MISUNDERSTANDING the
rock unstrGtifed, not slaty. 1t differs widely in
the degree of fineness of the three ingredients
composing it. the mica sometimes being in
plates two feet or more in diameter; at other
times in fine spanges, like scales, thickly scat
tered through the rock. The quartz or ielspar
also vary greatly in the size of the masses COM
posing the granite.
Fine granite is best fitted for purposes Of
architecture, for which it is extensively used in
many countries In the u States ere many quar-
rieS, furnishing building materials for all our
seaports, and many inland towns and villages.
No. S.-GNEIss is slaty granite, rendered so
by the uniform direction of the mica. 1t hence
splits in slabs of large and smooth surface, fit
ting it for sidewalks, floors, bridges, and many
other purposes of economy and convenience. Ii
is the prevailing rock on New York island, as
it is in many parts of New England and many
other parts of the world The color Of gneiss
depends, Of course upon that of the materials
composing it, especially the mica, which is
sometimes black, giving black or dark color
to the GUESS 1t is more commonly Of light
ish gray, and sometimes siyery.
No. 9.-MICA SLATE resembles gneiss, but is
composed OF quartz and mica. telspar COM
posing part.of granite and gneiss, is wanting
in this rock. Ii frequently has an unduating
surface bat is smooth. Ii splits readily, and
is used for purposes similar to those of gneiss.
Garnets are more abundant in this than any
other rock; and this rock contains more OF
those than any other crystals.
No. 10.-HoRNBLEND is black, green, or other
dark colors. 1t is more tough than hard and
is an element of rocks much used in architect
ure, also forming some of the most beautiful
scenery in the world.
No. ll.--SIENITE is commonly called gran
lite, but differs from it in taking hornblend in
place of mica. The Bunker Hill Monument
(Massachusetts) Merchants Exchange, Aston
House, Rutgers Institute, and numerous other
buildings, in New York and other cities, are
built of sente, commonly called Quincy gran
ite Cleopatras Needle, Egypt is sienite.
No. 12-BAsALT. The Giants Causeway il
composed of basaltic pillars, many of which
are six-sided prisms from six inches to foot
or two in diameter, in blocks about the same
length, with one end rounded and the other
followed, so as exactly to match, and are piled
upon each other to the height of 200 feet or
more Rocks nearly resembling these, and
piled upon each other in q similar manner,
form the Palisades on the Hudson the two bluffs
at New Haven, Mount Holyoke, and many
other mountain masses in this and other coun-
tries. The same kin d of rock is scattered over
many countries, in the form of powders, and
is frequently known by the name Of ironstone.
1t is composed principally Of hornblend or
augite, which it resembles, and felspar, with a
large portion of iron. Basalt, greensboro, and
other rocks of the same family, are much used
for building
Nos 10 and l4.-LIME formations are ex-
tensive various, useful, and sometimes beaut-
full. They embrace common limestone, nearly
all marbles, chalk, and many beautiful crys-
tails The older formations are in coarse grains,
which give it the name of granular lime The
more recent is frequently finer or more COM
pact when it is called compact lime. Ii is fire.
quenty found in rhombic crystals, when it is
called rhomb spar. When these crystals are
transparent they are called Iceland spar, and
produce double refraction-giving one line or
letter seen through it the appearance of two.
All these formations are the carbonate of
lime, composed of lime and carbonc acid.
When burnt, the acid is thrown from the lime,
when it is reduced to quicklime, and fitted for
various uses in building also for manuring
land, for which it is extensively used White
limestone and milk quartz are sometimes con-
founded but they may be easily distinguished
by the knife, as the former can be cut, and the
latter not and more certainly by an aoid as
the former effervesces, and the latter not
No. 15.-GYPsUM is the sulphate of lime
and Of course composed of sulphuric acid Toll
Of vtriol) and lime. In Italy and other coun-
tries, it appears in the form of alabaster, which
receives fine polish, and is translucent When
crystallized in transparent plates, it is called
selenite (moonstone 1t sometimes appears in
fine silky fibrcs, when it is called fibrous gyp-
sum. Radiated gypsum is another beautiful
variety of this mineral
Gypsum is a powerful manure, and is much
used for ornamental work in plasterng rooms !;
also for busts and casts of various kinds.
No. l6.-SERpENTINE rocks form extensive
barren ridges, but contain chrome ore, magne-
STA, asbestus, and Othor useful and curious de-
posts. 1t takes its name from its variety of
colors like the serpent, though its prevailing
color is green. The prevailing rock at Hobo
ken and Staten Island is serpentine which ex.
tends, with frequent Interruptions through
New Jersey, Pennsylvania, and Maryland, into
Virginia. Ii abounds in various parts of the
world.
No II. TALc, like serpcntine contains
II is sometimes known by the name
of French chalk. 1t has greasy feel, and is
easily cut with knife, or scratched by the fin
ger nail.
No. 1S--SoAPsToNE is composed of tale,
infinitely combined with quartz Il is easily cut
with an axe or saw, turned in lathe, smoothed
with plane, and thus changed into any form
desired for economy or convenience. IL is less
abundant than serpentine, but is frequently
found with it,
No. 19-SANDsToNE is composed of grains
Of sand or quartz cemented into rocks CON-
monty by iron. 1t abounds in many countries,
and is much used for buildings, and is the ma
terial for grindstones, whetstones, and other
similar articles.
No 20-PUpDINGsToNE is a rock formed of
pebbles and cemented by iron. The pebbles
are commonly quartz rounded by a long course
Of friction. When the pebbles are limestone,
not rounded the rock is called brcccia.
Nos. 81 and 22.--CoAL. Mineral coal is
divided into two great iamilies--btuminous
and anthracite. The former contains hydrogen,
which produces ready ignition, bright blaze,
smoke, smell, tar, and coke. Anthracite is
composed principally of carbon, which is ig-
nted less readily, produces little blaze, smoke,
Or smell, no tar or coke but higher heat and
is more durable. Bituminous coal is found in
Pennsylvania, Ohio, Illinois, Missouri, Tennes-
see, Alabama, and other States. Nearly all
the anthracite used comes from Pennsylvania.
Both are found in various parts of the other
sentiment.
No. 23.-FossILs. More than 5000 differ
INT kinds Of animals are changed into stone, or
petri6ed the greater portion OF the specie, now
extinct, or unknown in living state. Some
animals thus petri6ed were larger than eie-
plants; others are microscopic, or too small to
be seen by the eye alone. Microscopic animals
thus fossilized and now forming chalk, flint,