The Thread of Murder
| Published date | 01 April 1969 |
| Date | 01 April 1969 |
| DOI | 10.1177/0032258X6904200402 |
| Subject Matter | Article |
F.
E.
D.
GRIFFITHS,
M.B., Ch.B., D.T.M. &H.,
Home Office Pathologist, Birmingham M.C.Path.
W.
E.
MONTGOMERY,
Ph.D., D.I.C.
Director, Forensic Science Laboratory, Birmingham
THE
THREAD
OF
MURDER
In 5000 B.C., in the Upper Nile valley, Neolithic man was weaving
a linen cloth. This involved knowledge of the growing of flax,
separation of fibre from stem, fibre spinning to produce yarn and
the use of a loom to weave cloth. During the 7,000 years that
followed, textile developments have continued. At the end of the
19th century the viscose process was invented and the annual
production is now several million tons. The raw material is wood
pulp (cellulose) which, after chemical treatment, is dissolved in weak
alkali. The resulting viscous fluid is pumped through jets into an
acid bath causing coagulation of the cellulose and forming viscose
filaments ready for spinning. A few yearsago a process was developed
in Switzerland for producing hollow viscose filaments which would
simulate animal hair. .
Filaments growing from the skin of animals possess the
characteristic property of adhesion and this permits the spinning of
acontinuous thread or yarn. The outside of an animal hair is not
smooth but consists of a series of projecting processes or scales.
When two or more hairs come into contact the scales of different
hairs become entangled; the hairs cling together or become felted.
Hence, by the use of simple devices, hairs can be spun into yarn.
In the "Celta" process, for producing hollow viscose, traces of
bicarbonate powder are introduced into the viscous cellulose
solution. When the solution enters the acid bath a skin forms,
outlining the filament, and the acid, diffusing into the still liquid
interior, produces carbon dioxide from the bicarbonate particles.
The effect is to cause an irregular ballooning of the fibre forming a
chain of unequal swollen segments; when the gas diffuses out, the
swollen portions collapse to a flat ribbon. The final product consists
of very short pieces of ribbon joined by unexpanded filament of
circular cross section. A length of fibre as short as one millimetre
shows, in section, the collapsed ribbon, partly collapsed ribbon
with one or two gas bubbles and unexpanded filament, thus providing
a definite identification of the make of fibre.
April 1969 141
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