Port Tobacco times, and Charles County advertiser. (Port Tobacco, Md.) 1845-1898, 1851-02-12
AGRICULTURAL GEOLOGY.

.'Hdlne Farmer.
! AGRICULTURAL GEOLOGY.
BY JOSIAH HoLBRooK.
No. 4.
Feldspar is composed Of four oxydes-
slick, aIumina or clay, iron, and potash ST.
lex predominates. OF quartz, in all its va
rie'ies, it is almost the entire element; of
feIdspar, it is the principal; aluminous or
clay soils contain frequently twice as much
silex as alumina; the quantity Of iron and
potash in feldspsr is small, not often over
Two or three per cent.
1t appears then tha, sand is composed of
two oxydes or chemical combinations again
combined by the same agency. Feldspar
or clay is composed Of four oxydes, also
combined by chemical affinity, to form a
compound still more complex than quartz
or sand. The quartz and feldspar are COM
bined by a mechanical mixture TO form
rocks and soils.
1t hence follows, that in these two ele-
men's of soils, quartz and feldspar, or sand
and clay, are not less than six combinations
of ultimate principles, or oxygen and metals,
all by chemical affinity, and two combina-
tons at least Of those compounds forming
those two elements. These six chemical
compounds, again compounded by chemical
agency, are then united by mechanical mix
lures to form rocks and Soils
Quartz and feldspar are not only the es-
senlial elements Of soils, but also among the
most important materials in the arts of civil
liza'ion. The principal material of glass is
quartz; that of porcelain, feldspar. The
presence of potash, soda, or some alkaline
substance acting as aux, is indispensable
in the manufacturing Of each of these i'm
portant articles Of domestic economy.
After performing the imporlan. agency Of
producing vegelalion-of course furnishing
our wheat, our corn, our beef, and our
pork-quar'z of porous character consli-
tules the French burr, for changing grains
into flour. Pulverized quarts, cemen,ed by
iron into sandstone, forms ouE grinds,ones,
for sharpening the axes and chisels Of The
mechanic and the knives and scissors Of the
housekeeper. For some animals it is es-
sential 10 the process Of digestion fowls
cannot live without it.
Everything, animate and inanimate; every
product of nature and of art; every human
being in every position and condition Of
Ilfe-lle sturdy farmer, the busy mechanic,
the industrious housekeeper, the delicate
refined lady, the polished gentleman, the en-
ighened teacher, The wise statesman, and
the noisy politician: in a word, everything
which has physical existence bears visible
testimony to the necessity Of this important
element of mountains: rocks, and sols-of
quartz, sand-"a common sfone"
Experiment: Shake a lumber, containing
IA little newly-sIaked lime and some waller; :;
let the ,umber stand till the lime settles and
the waller becomes clear; pour the water
into another ,umbler and blow into it air
from the lungs through quill or pipe-stem,
the clear waller becomes lulbid with white
flakes or sediment, by the ca,b bonic acid
from the lungs uniting with the lime in the
water forming the carbonate of lime.
No. 5.
Mica is compound of oxydes, more COM
pounded than either qnar,z or fedspar. 1t
contains all the oxydes entering into both
these minerals, with the addition of magnese,
much used for bleaching salts, (chloride of
lIme.) Mica also contains traces of the sill
cate Of nagnesia-the article used in the
manufacture. EPSON salts and other chemi-
Gals. This silica,e, as lis name denotes,
contains slick, or the oxyde Of silcum. 1t
has been found by The progress of geology
in large quantities, both in Pennsy lvania and
Mary land. From it have been made various
chemicals, and among them epson salts,
(suIphae of magnesia,) at SO cheap rale,
in such quantities, and Of so good quality,
as entirely to supersede the importation of
this article, so extensively used for medi-
cinal purposes. In connexon with this ST.
lica.e and other magnetism minerals, chrome
ore (chromate Of iron) has been found, and
chrome yellow (chromate Of Iead) made
from it, with such success as to reduce the
price of tha. valuable paint from fifteen dol
lars to twenty-five cents a pound; thus
bringing the benefits of geology and chem
istry TO every individual in the community
at leas! to every man and woman who
rides in carriage with yellow paint, and
TO every child who uses an atlas with col
ored maps.
Mica is not an important element in soils,
and IN rocks is less abundant than either
quartz or feldspar. Though not abundant
in rocks, i! is one of the three materials of
granite, and has an important influence in