The free press. (Poplarville, Miss.) 1890-19??, 1899-01-12
MAGNETISM IN BRICKS.
Interesting Experiments Made by Professor
Lawrence at Rochester University.

Probably the idea that a humble
red brick would ever play any part in
electrical experiments has occurred to
few. However, this is just what a GER
tain lot of bricks composing a pier at
the Reynolds Laboratory did and will
continue to do as long as they are
within reasonable distance of the deli.
cate electrical instruments used in the
laboratory. A suspicion that the
above contingency might exist has
been in the mind of Prof. Henry E.
Lawrence of the University of Roches-
ter n. Y. for some time past. That
it is reality he now feels sure, and
the methods he used to come to that
conclusion are most interesting.
The professor. in cola boration with
Otis A. Gage, a special student in elec
tricity, began a series of experiments
covering some months. The perform
ance of magnetometer which was used
in measuring the magnetic power of a
steel bar was the first cause for sus.
pecting that the bricks were other than
what their appearance would lead one
| to thirk. The magnetometer had rest
ed on a brick pier for the purpose OF
making it plumb. Not long after Prof
Lawrence while in Ann Arbor, heard
of a similar experience occurring there.
| On his return the experiments went
on with more zeal than ever. Bricks
| of all varieties We're put through any
| number Of tests, and the great major.
ity were found to be magnetic. Those
manufactured by water power, known
as hydraulic" bricks, proved to be ex
ceedingly stro0g, one equalling the
power of a steel needle % centimetres
in length. This same block of clay
would make noticeable deflections in
comparatively crude instruments,
| while delicate ones would fiutter per
ceptibly.
One of the bricks. plain white one
| automatically pressed, possessed no
magnetism. A certain amount of lime
enters into the composition of a white
brick, such as was used. and its pres
ence undoubtedly had much to do with
the absence of magnetic power. 1t
was discovered that the bricks gained
magnetism in the presence of a dy-
namo, though the surrounding of the
bricks by wire coils made no percepti-
| BILE difference. Heating the bricks
served in a measure to decrease the
magnetism, though in each case a mi
mute amount was retained.
To lust what cause this is due nei
| ;, TO rot :
the present opinion, however, thai
there is more or less magnenite in the
clay of which the bricks are made.
The mode of manufacturing is also
thought to have something to do with
the phenomena. AS stated above, the
presence of lime served to decrease
| the magnetism. while the absence al
lowed of greater power. The profes-
sor thinks the Importance of his dis
! covery obvious. The slightest trace of
unsuspected magnetic power in the
structural part of laboratory is ne
cessarily fatal to nicely of electrical
measurements.
I That clay. when worked ever so
little by human agency gathers mag
netic properties has been thought for
some time Eminent Italian scientists
| have made innumerable experiments
| in that line during the past half dozen
/ years. Their greatest proof was
| found by experimenting with several
examples of ancient pottery which
had been buried for centuries. Crude
as they were, magnetism was found to
exist in no uncertain quantities.