he liquid and boil ten
minutes. Then wash the dyed fabric and notice whether the dyestuff
washes off or not.

2. Repeat the experiment, using the same weight of undyed woolen yarn.
Repeat with worsted yarn.

3. Repeat the experiment using the same weight of wool sliver.

4. Notice which has the deeper color. The degree of color depends on
the amount of twist in yarn. Which sample has absorbed the greatest
amount of dyestuff from the liquid?

_a._ Why is a yarn-dyed fabric faster than a piece-dyed?

_b._ Why is a raw stock dyed fabric better than piece or
yarn dyed?

=Experiment 21--Dyeing Cotton=

Apparatus: Porcelain dish, filter stand, etc.
Material: Piece of cotton cloth.
Reference: _Textiles_, page 67.

_Directions_

1. Prepare a solution of coloring matter by dissolving a half ounce of
logwood in a quart of water. Filter the solution. Place a piece of
cotton cloth in the liquid and boil ten minutes. Then wash the dyed
fabric and notice whether the dyestuff washes off or not.

2. Repeat the same experiment and use a piece of cotton cloth that has
been previously washed in common alum.[25] Note the effect. Which has
the greater attraction for dyestuffs, cotton or wool? Why is alum
used?

3. Repeat the same experiment, using first the same weight of cotton
yarn and then the same weight of cotton sliver. Notice the results.

Which piece of cotton holds the dye best, that which was dipped in
alum or the one that was simply boiled in the solution?

=Experiment 22--Weighting Silk.--Affinity of Metallic Salts for Silk=

Apparatus: Porcelain dishes.
Material: Silk yarn.
Reference: _Textiles_, pages 212-214.

_Directions_

1. Weigh separately two skeins of dry silk and distinguish skein No. 1
by looping some cotton thread into it. Prepare a tepid bath containing
10 gm. strong sumach extract in 400 cc. water. Enter the skeins of
silk and work for 15 to 20 minutes, meanwhile slowly raising the
temperature to about 150 deg. F. Remove, squeeze, rinse with water,
squeeze, and dry skein No. 1 for weighing.

2. Meanwhile prepare another bath containing 4 gm. of copperas
(ferrous sulphate) in 400 cc. cold water. Work skein No. 2 in bath for
10 minutes cold. Remove, and rinse well; save the iron bath. Repeat
the treatment in the sumach and iron baths several times more, finally
wash the sumach iron skein in 1 per cent hot soap solution; rinse,
squeeze, and dry. Weig