reen, etc.,
which may be dyed on the cotton, and so it becomes necessary to remove
this colour and render the cotton quite bright. This is commonly called
"bleaching". It is these preparatory processes that will be dealt with
in this chapter.

=Scouring Cotton.=--When dark shades--blacks, browns, olives, sages,
greens, etc., are to be dyed it is not needful to subject the cotton to
a bleaching operation, but simply to a scouring by boiling it with soda
or caustic soda. This is very often-carried out in the same machine as
the goods will be dyed in; thus, for instance, in the case of pieces,
they would be charged in a jigger, this would be filled with a liquor
made from soda or from caustic soda, and the pieces run from end to end,
while the liquor is being heated to the boil--usually half to
three-quarters of an hour is sufficient. Then the alkali liquor is run
out, clean water run into the jigger and the pieces washed, after which
the dyes, etc., are run into the jigger and the dyeing done. There is
usually used 2 lb. to 3 lb. of caustic soda, or 3 lb. to 4 lb. of soda
for each 100 lb. of goods so treated.

If the ordinary dyeing machines are not used for this purpose, then the
ordinary bleachers' kiers may be used. These will be described
presently.

=Bleaching of Cotton.=--Cotton is bleached in the form of yarn, or in
the finished pieces. In the latter case the method depends very largely
on the nature of the fabric; it is obvious that fine fabrics, like
muslins or lace curtains, cannot stand the same rough treatment as a
piece of twilled calico will. Then, again, the bleaching process is
varied according to what is going to be done with the goods after they
are bleached; sometimes they are sent out as they leave the
bleach-house; again, they may have to be dyed or printed. In the first
case the bleach need not be of such a perfect character as in the last
case, which again must be more perfect than the second class of bleach.
There may be recognised:--

(1) Market or white bleach.
(2) Dyers or printers' bleach.
(3) Madder bleach.

As the madder bleach is by far the most perfect of the three, and
practically includes the others, this will be described in detail, and
differences between it and the others will be then pointed out. A piece
is subjected to the madder bleach which has afterwards to be printed
with madder or alizarine. Usually in this kind of work the cloths are
printed with mordant colours, and th