Evening star., 1898-12-26
MAGNETISN IN BRICKS,
Inferesttng Experiments Made at the
Rochester University.

From the Rochester Democrat and Chronicle
Probably the idea that Il humble red
brick would ever play any part in electrical
experiments has occurred to few. However
TINS Is Just what certain lot of bricks
composing pier at the Reynolds Labora-
tory dld and Will continue to do as long
as they are within reasonable distance of
the delicate electrical Instruments used in
the laboratory. n suspicion that the above
contingency might exist has been in the
mind of Prof. Henry f. Lawrence of the
University of Rochester for some time past
That IT IS reality he now feels sure and
the methods ne used to come 10 that con-
clusion are most interesting
The professor in collaboration with Otis
A Gage, special student i'll electricity
began series of experiments covering
some months. The performance of the mag
netometer which was used in measuring
the magnetic power of d steel bar was the
first cause for suspecting that the bricks
were other than what their appearance
would lead one to think. The magnet
umetcr had rested on brick pier for the
purpose of making it plumb. Not long
after Prof. Lawrence, while i'll 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 were put through any number
Of tests, and the great majority were found
to be magnetic. Those manufactured by
water power, known as hydraulic" bricks
proved to be exceedingly strong. one equal
ing the power of a steel needle 2.3 cent?
meters in length. This same block of clay
would make noticeable dehectIons in com
paratively crude instruments while deli
cate ones would fiutter perceptibiy.
One of the bricks, a plain white one
hydraulically pressed possessed no mag
netism. certain amount of lime enters
into the composition of white brick such
as was used, and its presence undoubtedly
had much to do with the absence of mag
netic power 1t was discovered that the
bricks gained magnetism in the presence
of a dynamo, though the surrounding of
the bricks by wire coils made no perceptibe
difference. Heating the bricks served in a
measure to decrease the magnetism, though
IN each case minute amount was re
tanned.
To just what cause this is due neither
gentleman is ready 10 state 1t is the pres
ent opinion, however, that there is more or
less magnetic in the clay of which the
bricks are made. The mode of manufacture
ing 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 allowed of
greater power. The professor thinks the
Importance of his discovery obvious The
slightest trace of uususpected magnetic
power in the structural part of a labora-
tory is necessarily fatal TO nicely of cleo
trical measurements.
That clay, when worked ever so little by
human agency. gathers magnetic properties
has been thought for some time Eminent
Italian scientists have made innumerable
experiments in that line during the past
| nail dozen years. Their greatest proof was
| found by experimenting with several ex-
ampies of ancient pottery, which had been
| buried for centuries. Crude as they WERE
magnetism was found to exist in no uncer-
tain quantities.