The broad ax., 1924-01-05
To Determine ALI
Wool Dress Goods
Burning or Acid Test VIII
Settle Question When
There Is Doubt.

At this season Of the year, aim 1st
every woman is buying wool dress ma
terial, notes a fashion correspondent.
The question uppermost in her mind as
she Is trying to choose the best for
the money she feels justified IN spend
Ing Is, How much Of this is woolg"
Some Jew brands of cloth have ALI
wool guarantees, and very few large
stores have testing laboratories where
cloth samples may be tested, but for
the large majority Of women purchas-
ers the testing must be done by them
selves, and in their own homes.
Most wool and cotton mixtures are
made after the yarn is spun. Because
of this, the thread test, made with
threads raveled from cut sample, is
the most satisfactory. Tests must be
made on threads going in each direction,
for substitution is often made il the
warp while an all-wool filling is used.
The simplest method of determining
the character Of the thread Is by the
burning test A thread of cotton will
burn with flash and almost no odor,
while one of wool burns slowly, almost
melts back, and gives off the familiar
acrid odor.
This simply tells whether or not a
certain thread is WOOL 1t is not prac-
teal as test for the percentage of
wool in a given sample. To determine
that more complicated methods will
be needed, but in the household where
much sewing is done it will pay to
provide the material necessary and to
test each sample before purchasing.
The materials necessary are two
small glass beakers, a glass stirring
rod, a bottle Of so per cent solution Of
nitric acid, one of strong household
ammonia and one of 5 per cent solu-
ton of either sodium or potassium
hydroxide. A gas jet or alcohol lamp
win be necessary to furnish heat and a
small metal stand with a square Of
wire gauze on which the beakers may
stand.
If the material Is white or light-col-
ored the nitric acid test is most evil
dent. Cover the samples to be tested
in one of the beakers with nitric acid.
In few moments the wool will turn a
bright yellow. for nitric acid win turn
any animal fiber that color. Cotton is
unaffected. Pour off the acid, wash In
clear water and cover with ammonia.
This time the yellow threads win turn
-
and wool has been made in the yarn
when cardlng, as is sometimes the case
in flannel, 1t may be thus detected.
Dyed materials will not show the
nitric acid tests, so other methods
must be used with them. Wool dis
solves If boiled for ten minutes in
either the sodium or potassium n.y.
droxide. Cotton is unattached. Some
times this win prove a complete set of
cotton threads one way. Often it win
simply weaken the web in both sets of
threads. At any rate. it win show
you whether you are buying wool or
cotton.
Often it Is economical and practical
to buy cotton and wool mixtures, espe-
cially if the material must be laund-
cred. But you really are entitled to
know which you are getting and to
pay the price accordingly.
Care must be exercised in the use
Of acids to avoid touching other ma
teriaIs or getting them on ones hands.
Bottles containing the solution used
should be plainly marked and not
kept in the same place with any medI
cines. They are poison and should be
labeled such.