Clarksville weekly chronicle. (Clarksville, Tenn.) 1873-1890, 1877-09-15

nature. We think them better sep
arated, and would like to see a
short, simple, practical work on the
principles of equilibriumand motion
of bodies, including the mechanical
powers, such as lever, wheel and
axle, pulley, ETC., with simple APP
paratus all this to be Illustrated
with very simple apparatus, and to
constitute subject by itself. Then
we would have the forces of nature,
as heat, light, electricity and chem
zeal affinity, all taught as a part of
chemistry But now comes our
great difficulty. Unquestionably
chemistry should be held an indis-
pensable part of education in an agri-
cultural community, but at the
same time we have never seen a case
where a practical knowledge of
chemistry was acquired by boys at
school. Is it impossible to do so I?
We are unwilling to believe it with
out an intelligent attempt to do so,
and we are strongly of the opinion
that the intelligent attempt has not
vet been made. We have of late
taken the trouble to look over half
a dozen of the ordinary school chem
istries and are fully satisfied that an
essential preliminary to teaching
practical chemistry in schools will
be to burn the whole lot of them
and start fresh; they all (physics
and chemistry BOTH adopt the prin-
ciple of commencing with the alb
stract and proceeding from that to
the concrete, the very opposite to
the obvious way in which we prac-
ticaily become acquainted with eX-
ternal nature. We begin with OBJ
serving things as we find them and
by noticing their resemblances and
differences, the changes to which
/ they are liable under given circum-
stances, we gradually infer certain
principles or lars to which they are
subject. On this principle we pro-
pose to dispense with all the crude
metaphysics the boy encounters at
/ the threshold of science about the
properties of matter, and leave the
/ definition of them till he has become
/ familiar with them as facts. Again,
school chemistries always give us
the elementary substances first and
/ then proceed to their combinations.
We don't so meet with them in ma
ture. NOuncOmbined element occurs
i'm nature; we don't get oxygen or
hydrogen, calcium or aluminium in
the elementary condition in nature.
Let us take what nature furnishes
us, and proceed from the known to
the unknown, from the familiar to
the abstruse. Here is how we would
introduce the subject of chemistry
to a class of boys of average intelli-
gence in an agricultural community.
We would first present to such a
class three specimens of soil just as
they might be brought in from the
fields-a stiff clay soil, a light sandy
soil, and one in which limestone
predominated. heyshOuld at once
be familiarized with the physical
qualities of the two former soils.
Let an equal quantity of each be
shaken up in glass vial with water
and point out how much more rap
idly the light soil separates and set
ties, the clay specimen remaining
turbid for a larger time. Then re-
verse the experiments and, putting
an equal quantity of each into fun
mel, pour water through them and
show how much slower the water
passes through the stiff soil than the
light soil. This done, repeat the eX-
pertinent on pure clay and pure sand
and show how the above phenOme-
Ma are more strongly marked then,
and make them understand that the
characteristics of stiff and light soils
depend upon the predOminance of
clay or sand in them. Especially
make them repeat these expert
ments for themselves. Then take
your limestone soil, and shaking
up, as before, little of it in water,
show its efferVeScence when muriat-
ic acid is added, and when the liquid
becomes clear add some sulphuric
acid so as to percipitate the lime,
and explain to to them the presence
of carbonate of lime as accounting
for the characteristics of limstone
soils. Now present to them pure
specimens Of alumina in clay pre-
pared for pottery; silica in the form
of quartz and carbonate of lime in
that of marble or chalk, or both Of
them, and they will understand that
they have all the essential cOnstitu-
pnts of the different soils; and you
have done your first lecture.
You have yet resolved nothing
into its elements, and you need not
be in hurry to do SC, 6ithGr; it
will not be long before they will un=
derstand that these constituents are
combinations of the elements, alum
mum, silicon and calcium with
oxygen; but before you tell them
that, give them some idea what
oxygen Is, For this purpose eN-
plain that the productiyfpess OfsOils
depends upon the action of air SnG
water upon them, and giving the
simplest experiments in the analy-
sis of these two substances, separate
their elements of hydrogen, oxygen
and nitrogen, demonstrating the
characteristics of each. Ipsulate
some of the carbonic acid develop
ed in yesterdays, experiment, and
familiarize them with the simplest
combination OF the four elements
they have had to deal with, name
iy, water, ammonia and carbonic
acid-th6ER is your second lecture;
and in tbp third the actual Teduc-