Vermont watchman and State journal. [volume] (Montpelier, Vt.) 1836-1883, 1879-08-13
The Young farmers Catechism.

THE COMPOSITION OF SOIL

CHAPTER II,
THE COMPOSITION OF SOILS.
Question-Are soils of one uniform sub
stance
Answer-No; rocks are composed of a
vast number of minerals, and soils contain
all the mineral substances of the rocks from
which they were formed.
Question-Will you name the more com
mon mineral substances that soils contain
Answer-Silica, aumina, lime, potash
magnesia, soda, sulphur, phosphorus, iron,
and the compounds of these substances with
each other, with water, and with oxygen,
nitrogen, hydrogen, chlorine, carbonic acid,
and ammonia.
QaeStion-What is silica
Answer-It is hard mineral called by
the chemists silicic acid. 1t is compound
of an elementary substance, silicon, with
oxygen gas. 1t is also called slick, and as
it is found naturally we call it flint, quartz
jasper, agate, aud when broken into small
grains, sand.
Quesiion-What is alumina?
Ans~er-lt is an earth, or earthly sub
stance, contained in clay. The finest pottery
clays are nearly pure silica and alumina ;
our common clays are composed OF silica and
alumina mixed with silicious sand, lime,
iron and other impurities. Alumina is also
a constituent of rocks, particularly GRANTEES
and states. Alumina is composed of metal
(aluminum) united with oxygen gas This
metal is somewhat used in the arts Were it
not so difficult and expensive to extract it
from clay, it would be very useful, since it
is superior to lead or tin Tor most OF the
purposes to which those metals are applied,
and its ore, clay, Is everywhere abundant
Questlon-What is lime
AnsUer-ltls mineral winch exists In
combination with caroonc acid gas under
the name oil limestone when subjected TO
a strong heat, the carbonic acid is driven
off, and we have lime, called also quick-lime'
This quick-llme when exposed to the AR
absorbs water and caroonlc acid, and
ia'ls into POWDER called air-siaked lime
fure lime Is compound OF a metal
(calcium) with oxygen gas
Qaesi'n-What Is potash
ns~er-lt Is mineral substance enter
Ing into the composition OF one species OF
the rock called 1eidSpar' feldspar Is found
pure, but exists most aoundantly as a com
ponent OF granite. Potash, like alumina
and lime, is compound OF a metal with
oxygen. This metal (potassium) has so
great an affinity for oxygen that it cannot
be kept exposed to the air, and is conse-
quently not common, though used by chemists
for some purposes.
Question-What is magnesia -?
Answer-A white earthly substance, com.
posed OF a metal (magnesium) united with
oxygen. 1t is constituent of kind of
limestone, to which the name of magnesian
limestone, or dolomite, is given. The metal
magnesium, when drawn out into wire, may
be burned in the flame of lamp. 1t emits
very bright light in burning, and the ashes
or fine white powder which is left after the
burning, is pure magnesia. Burning, il
this as in other cases, is simply rapid unior
with oxygen (oxydation). Slow oxydation
as when iron is rusted in the air, does moi
produce light, and the heat produced is moi
sufficient to be sensible to the touch. But
pure iron, in very Fl lie POWDER will burr
rapidly when exposed to the air, giving
very strong heat. Aud iron wire will burr
in jar OF oxygen gas as brilliantly as tn
more easily oxydizable magnesium burns il
the air, which is mixture of oxygen AM
nitrogen.
Qaesiion-What is soda :
/, Ansper-An alkaline substance, resem
bling potash, and like it the oxyd of meta
called sodium, which, like potassium, ca
only be kept from rapid oxydation by keel
ing it from the air. When potassium
thrown upon water 1T burns brightly, an
the potash thus formed unites with tn
water, forming apure potash I've, from whic
the potash can be extracted by boiling, tn
2 same as from the I've OF wood ashes. Sodiur
does not oxydizs upon water 80 rapidly a
a to flame, but is converted iuto soda yer
quickly, aud this dissolyes like potash, NAL
e ing soda I've. Both of these metals ar
, very light, as is shown by their floating upo
e water. When protected from oxydatio
4 they have metallic luster, like lead or tin