Evening star., 1936-02-16
Detective Work of
Standards Bureau
BY Frederic ]. Haskin.

STANDARDS, Tor 1t contains many Of the
elements Of solution Of a baffing set Of
facts. The only murder involved was the
murder and mutilation of linen napkin.
The solution resulted in the acquittal of
laundry which lay deeply under
suspicion.
Privately conducted textile laboratories
such as that maintained by the Textile
Institute and those of big laundries have
wrestled with the mystery of damaged
linens. In some cases the presence of
cleansing agents in the water used has
been found guilty but not always. One
mystery which had not been unraveled
was brought to the National Bureau of
Standards and. after patient investiga-
ton, the solution has been found.
A piece of linen was brought to the
textile section of the bureau some time
ago. 1t had been hemmed as napkin
and seemed to be in good condition. 1t
was sent to laundry and, upon its re-
turn, it was found to have several large
holes. The first natural assumption was
that the laundry was at fault. But the
detectives of the bureau observed that
the holes were symmetrically placed
along the folds of the napkin, and this
proved to be the clue. For the holes to
be so placed created strong supposition
that the deterioration had taken place
while the napkin was folded. AS it would
not remain folded while going through
the laundry, it was clear that the damage
must have occurred at some other time
and in some other manner. Further, a
chemical analysis showed that no chem
ical was present in the fabric which
could account for the damage,
With the patience of Scotland Yard
sleuth, the bureau looked into all the
circumstances, the case history of this
particular bit of linen. 1t was discov-
cred that the linen had been hemmed
into a napkin and then laid away for a
number of years in the drawer Of a sew
ing cabinet in a living room. Why a
number of years had passed without the
napkins being brought forth and laun-
dered is another story which was no
concern of the bureau and has no part
in this mystery. The fact is enough.
What is of major Importance, however,
is that in the same drawer in which the
hemmed napkin had been found were
also found several pieces of unworked
linen. Whoever had started the work
had finished but one napkin; the other
pieces Of linen were untouched so far as
needlework is concerned. These were
taken to the textile laboratory and ex-
amined just as they were found. It is
regarded as fortuitouS circumstance for
science that whoever tossed the one fin
ished napkin in the laundry left the other
pieces where they were. For, on exam
ination, it was noted that even in an
unlaundered state the pieces of linen
were found to be seriously deteriorated.
In some places the textile was so brittle
that the fiberS crumbled into dust when
rubbed together between the fingers.
At this stage of the inquiry 1t became
clear that the laundry was exonerated.
The linen was ready TO fall to pieces
before the one hemmed napkin was sent
to be washed. That was all very well so
far as it went. but knowledge of the
culprit was still lacking. The sewing
table seemed to be innocent. 1t had
been in a well-ventilated living room
and not in damp cellar or any such
inhospitable place.
So the sleuthing continued. In this
sewing table, among other implements
of needlecraft. there were found some
knitting needles The bureau is thorough
and, while it had no a priori reason for
suspecting the knitting needles, still it
decided to examine them. 1t was found
that they we're not steel knitting needles,
nor ivory, but were of one Of those fairly
modern plastic materials, the sort that
can look like amber. Moreover, the
bureau discovered that the needles were
not in good condition. They we're found
to be weak and brittle.
This was long step, but as yet was
not conclusive. The needles were sub
jected to the closest analysis and it was
found they were made of celluloSe- nitrate
plastic. This is material which. when
new. is hard and useful, but which Is not
very stable The chemists of the bureau
had discovered that in the course Of slow
deterioration this synthetic material lib
crates oxides of nitrogen. The mystery
of the linen napkin was solvedl Nitric
acid. formed by the liberation of gases
in the deterioration of the cellulose-
nitrate needles, inSidiously attacked the
linen over the period of time it had re-
posed forgotten in the sewing cabinet.
mutilated by knitting needles before 1t
ever went to the laundry.
IF the owner of the deteriorated
linen," comments the bureau. had not
been obServant and had not furnished
all of the material bearing on the prob
lem, the cause of the deterioration prob
ably would have remained mystery"
~ ~ ..
The National Bureau of Standards
undertakes many detective assignments.
many in the interests of manufacturers.
An investigation has just been made to
determine causes Of various breaking
strengths in cotton cloths. While to
the layman, unequipped with microscope
or other precision instruments, the yarns
or strands in piece Of cotton cloth look
much the same. there often is a great
difference. When a machine is weaving
from yarns measuring around 1-70th OF
an inch in diameter it is difficult for the
eye to determine unaided whether some
of the strands are 1-80th and some
1-60th of an inch. Yet such differences
make a material difference in the strength
of the cloth. Tests have revealed that
piece of cloth is only as strong as the
yarns of which it is made. The stress
which will break very thin yarns will
break a fabric made of those very thin
yarns. By making sure in advance Of
the uniformity of yarns woven into cloth
stronger fabrics can be made-Strong
enough, indeed, to be used for parachutes,
where the strain is intense.