The Republican. [volume] (Oakland, Md.) 1877-current, 1910-05-26
DETECTING BLOOD STAINS
Is Simple Matter With Modern Chem
icaI Outfit.

People often wonder why it is |
that experts, when given evidence |
in court, can so confidently affirm
that certain substance removed |
from clothes, weapons, and so on
consists of blood, although the
suspected parties declare it to be
rust or red paint. The determina-
ton of the truth is, however, a
matter of simple preparation and
microscopical observation which
is absolutely infallible, for reasons
which l will give.
The reader has probably learnt
at school that all human blood
consists of two kinds of densely-
packed globules invisible to the
naked eye, called corpuscles, white
and red, floating or suspended in
a liquid, doubt whether one
person in a million-aside from
those who study such topics-has
any real idea of the minuteness of
these objects 1t is useless to say,
for instance, that ten million of
the red corpuscles will cover a
square inch if laid out quite flat.
1t is the function of the white
corpuscles to consume the bacteria
and bacilli that enter the blood,
and they are actually alive. The
red discs contain the iron of the
blood This much enables US to
proceed with understanding.
I squeeze a mere drop from
needle prick in my finger on to a
slide. At first all the globules
and discs are fairly we'll defined,
though it is usual to add a drop |
of water, or a chemical solution,
to separate them and render them
clearer, Slowly the drop stiffens,
the hrmness commencing at the
edge, which is paler than else
where, and proceeding inwards.
Within.a short time it has wholly |
concealed. The edge is family
frilled, while tuft-like darker lines,
the fibrin, are observable near it
The lengths Of the tufts increase
toward the centre of the spot in
the vicinity of which are compare
lively large cracks dividing the
film iuto plates like those on a
tortoise's back. No beads are
then present. This feature Of it.
self affords a good clue to the clev-
erer analysis if the substance is
not too old. l wait till the next
day before making the tests.
The dried blood is eventually
loosened with thin, sharp knife
blade, and comes away like a feck
of india rubber or leather, or SINH
lar resistant, yet pliable stuff.
detach all except the portion to
be tested Then l let fall a drop
of glacial acetiC acid onto the
dried fake, and tiny speck of
common salt and gently warm the
mixture. Upon replacing it be-
meath the microscope the liquid
cools and evaporates. and there
strangely springs into view a mass
of red-brown crystals, or maybe
scattered ones, having definite
characteristic shapes. The chem
ical reactions have been of a very
curious kind. Before the appear
anCe of the crystals, bubbles of
gas, etc. emerge from between
the cracks separating the minute
plates, and burst in due course.
Then the edges of the plates be-
come fainter and fainter until all
red tint is absorbed, and the crys-
tails commence to appear at various
points.
The substance forming these
crystals, composed of chlorine
from the salt and eXtractions from
the blood combined, is known as
haemin, or chloride of haematin.
The crystals will undergo another