Rock Island daily Argus. (Rock Island, Ill.) 1886-1893, 1889-10-14
BRICK TESTS.
Interesting Report OFFS II. south~en
an Experiment with Paving Ma
teriaIs

Interesting Report Of II. southweII
of an Experiment with Paving Ma.
teriaIs.
Recently Mr.. Phil Mitchell, of the
committee on brick factory of the Rock
Island Improvement association, submit
ted to Prof. j. II. Southwell for analyti,
cal test the sample of paving brick clay
received from Gslesburg and sample of
the deposit found in the eastern part of
Rock Island. The following is Mr..
Southwelrs report on the subject:
Mr.. PHIL MITCHELL: Dear Sr:-I
have examined the sample of clay you
gave me that came from the eastern part
of this city, and also that which was
found by MIR Nevins with a car load OF
the paving brick. This last, it is sup
possible, represents the material from
which the paving brick is manufactured.
The first mentioned contains a large pro-
portion of ksolinite or silicate of alumni,
mum, but no free silica or sand; is of
dark color, but the color does not seem to
be due to the presence of a hydro>carbon.
IL feels somewhat soapy which is caused
by the large proportion OF kaolin and the
absence of silica in the form OF either OBJ
servsble or impslpsble sand. 1t shows
no trace of soda, potash or any alksli,
but on the contrary, the litmus exhibits
the presence of some organic acid. When
dry the mass possesses noticeable
cleavage with tendency to split up into
irregular horizontal plates.
The piece of dry clay from the car of
paving brick shows no tendency to cleav-
age in any direction, but it breaks under
the hammer into pieces that seem to have
4 tendency TO roughly initiate in form
rhombohedrous or blocks with lozenger
shaped ends. n is of gray color
and quite hard and stone-like
A microscopic examination reveals a very
fine powder Of quite regularly rounded
grains. which the polariscope proves to
be silica. When this powder is viewed
under magniicstIon OF one hundred
diameters it appears very much as the
ssltpeter sand, which you use at the glass
works, does to the unsided eve. This
powder sand, You will observe must be
Of grain, exceedingly small-it was
ground in the mills that grind slowly
for, at the above mentioned rate of mag
MITIGATION. one grain of glass sand would
furnish enough silica for ten thousand of
these particles Fifteen to twenty-five
per cent of the piece of clay from the
car consists of this very fine sand.
The remainder is mostly kaolinite.
IL also contains some iron, proba-
bly, in the form of carbonate,
which. in burning. becomes changed to a
red oxide. giving the brick its color. In
ternally mixed with the mass are particles
of csrbonaceous substance. as If large
quantity of the clay had been ground
and thorough y mixed with few pounds
of coal
No alkah appears to be present. With
the constituents mentioned above the
addition of a little potash or soda would
cause the substance to become highly
vitri6ed in burning.
l think that clay similar to this piece
from the car may be found about here-a
little careful examination would demon
strate this. / imagine that good paving
brick clays could be found in the western
part of Andalusis and northern parts of
Buffalo Prairie and Drury townships. and
clay at Carbon Cliff may be found, upon
trial, suitable for this purpose.
Respectfully.
J. ii. SoUTHwELL.