Year: 1861

The difference between chemistry and
mechanics can be very clearly explained by.
the changes produced Oh sand. Thus If VIC
take piece of quartz and reduce it to pow.
der it becomes sand This is simply me-
chanical change, the sand remaining OF the
same nature as it was prior to its beng re
duced to dust Silica is the chemical name
for quartz, and it is one of the most refrac-
tory substances known. 1t is perfectly ins
soluble in water, and neither sulphuric-
hydrochloric nor nitric acid will dissolve i5-
1t is also so infusable that it cannot be melts
ed by any heat obtained by the blow pipes
and yet this substance. so hard, so infusible
and insoluble, can readily be converted inte.
soap and made to melt like wax through the
subtle agencies Of chemistry BY taking
some sand and mixing with it a portion o..
caustic soda carbonate of soda and lime
and submitting these substances to verse
high heat in melting, pots placed in furn-
ace, it fuses and becomes glass. In K.
molten state it is blown into bottles and ves-
sells Of every variety of form, andis also
converted into sheets for window panes,Sansds
moulded like clay for many other purposes. !.


Glass contains just sufficient quantity OF
alkal to render it fusable, but not soluble, ),
as neither water nor the three acids named
dissolve it; indeed, glass, is the SUBSTANCE
commonly used for containing those very.
corrosive acids and for this purpose it is of
inestimable value to the arts The change
produced by the soda on silica is a chemical
one. The moulding of glass, when fused.
so as to change its form is mechanical
principle; the action of the soda upon the.
silica in conjunction with the high heat in.
the furnace, whereby the silica is made fusi-
BILE, is chemical one, and the compound
thus formed, which we call glass, is a sill
cate of soda. A still more wonderful change
than this is effected if an excess of caustic
alkali is combined with the silica, as it then
forms what is called soluble gllss," a sub
stance which will dissolve by being boiled
in water. Soluble glass (silicate of soda)
is best formed by boiling finely subdividea:
sand in very caustic lye under steam pres
sure, so as to subject the silica to the high
est possible temperature, as this tends to
form more concentrated solutions of the
silica This is also chemical change
The hard silica, formerly SO insoluble, unitas.
with the excess of alkali and really becomas
a soap which is now used IN Prussia dssa
some other places for washing purposes. 4
The silica takes the place Of tallow, oil and
grease, which are used for making common
soap. and uniting with the alkali it becomes
soluble in water, and may be used for wash
ing as an inferior saponaceous compound.
Such are some of the mysteries of chemistry.


Silica is one of the most common and use
full substances in nature 1t is the constitu-
ent Of many rocks and composes most of the
pebbles in gravel beds Rock crystal is
pure transparent quartz, and it's name is
derived from Arustallos, Greek word sig
nifying ice. Silica is the base Of great
number of precious stones, such as the car
nelian and sardonyx, which are bright red;
also the opal, &c. We are entirely depen-
dent upon silica for our present advanced
position in some of the arts It forms the
lenses Of the telescopes by which such ad


vances have been made in astronomy. and
from it the lenses are made for our most
improved system of lighthouse illumination.


Spcctacles, those aids to the aged, are
also formed Of it, also our windows and look


ing glasses in short, silica is applied to
numberless purposes in all the philosophi-
cal, useful and elegant arts. The little
grains of sand' have become mighty agents
in the hands of cultivated man. 1t is said.s
however, that the ancieEts were acquainted
with the art of making malleable giass-an
art which, if it ever existed, can be re-dis-
covered. - Standardization.