dium chloride,
potassium sulphate, sodium sulphate, etc., have no action whatever on
the wool fibre.

Wool has a strong affinity for many colouring matters. For some of the
natural colours, turmeric, saffron, anotta, etc., and for the neutral
and basic coal-tar colours it has a direct affinity, and will combine
with them from their aqueous solutions. Wool is of a very permeable
character, so that it is readily penetrated by dye liquors; in the
case of wool fabrics much depends, however, upon the amount of felting
to which the fabric has been subjected.

If wool be boiled in water for a considerable time it will be observed
that it loses much of its beautiful lustre, feels harsher to the
touch, and also becomes felted and matted together. This has to be
carefully guarded against in all dyeing operations, where the handling
or moving of the yarns is apt to produce this unfortunate effect.

After prolonged boiling the fibre shows signs of slight decomposition,
from the traces of sulphuretted hydrogen and ammonia gases which it
evolves.

When wool is dried at 212 deg. F. it assumes a husky, harsh feel, and
its strength is perceptibly impaired. According to Dr. Bowman, the wool
fibre really undergoes a slight chemical change at this temperature,
which becomes more obvious at 230 deg. F., while at about 260 deg. F.
the fibre begins to disintegrate. According to the researches of Persoz,
however, temperatures ranging from 260 deg. F. to 380 deg. F. can be
employed without any harm to the wool, if it has previously been soaked
in a 10 per cent. solution of glycerine.

When wool is heated to 212 deg. F. (100 deg. Cent.) it becomes (p. 014)
quite pliant and plastic and may be moulded into almost any shape,
which it still retains when cold. This fact is of much interest in
the processes of finishing various goods, of embossing velvet where
designs are stamped on the woven fabric while hot, and in the
crabbing and steaming of woollen goods, making hats, etc.

CHAPTER II. (p. 015)

PROCESSES PREPARATORY TO DYEING, SCOURING AND
BLEACHING OF WOOL.

Wool scouring takes place at two stages in the process of manufacture
into cloth. First, in the raw state, to free the wool from the large
amount of grease and dirt it naturally contains; second, after being
manufactured into cloth, it is again scoured to free it from the oil
that has been added to the scoured raw