Some Applications of the Spectrograph to Criminal Investigations
| Published date | 01 October 1939 |
| Date | 01 October 1939 |
| Author | F. H. Newman |
| DOI | 10.1177/0032258X3901200406 |
| Subject Matter | Article |
Some Applications of the Spectrograph
to Criminal Investigations
By PROFESSOR F.
H.
NEWMAN, D.Sc.
University
College,
Exeter
IN
aprevious article
(POLICE
JOURNAL, Vol.
II,
NO.3, 1938),
some particulars of
the
spectrograph, and the way in which
it is used, were given.
The
instrument is very useful in con-
ducting aqualitative survey of questioned materials.
If
the
results are negative, no further tests are necessary. If, on the
other hand,
the
analysis indicates
the
presence of elements
which would
tend
to incriminate, further analyses are made
by chemical means. One great advantage of
the
spectrograph
is
that
only minute quantities of material are needed.
Let
us
consider a few instances where spectrographic methods have
been employed in police work.
In
forcing a safe, a burglar used acommon iron bar,
and
a few days later the suspect was picked up
and
had abar in
the
house which corresponded
with
the
dimensions of the
marks on
the
safe-the
latter being painted green.
On
close
examination of the bar a few green smears were discovered on
the end. These were dissolved off by means of ethylene
bichloride and the residue tested in the arc by means of
the
spectrograph.
The
results were compared with those obtained
from the paint on the safe, and among
the
constituents from
both specimens were barium, chromium, lead and zinc,
the
latter coming from an undercoat of white paint.
The
similarity
of
the
paint smear on the bar and the paint from
the
safe door
were thus established.
In
another burglary case entrance
had
been made through
an opened window, on
the
sill of which was a faint film of
green vegetable matter which is often found on parts of build-
ings.
The
trousers of the suspect also had one or two green
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