he
method of bleaching separate hanks, partly because so many improvements
have been made in the hank-bleaching machinery of late years, which
enables bleachers to handle the yarn in the form of separate hanks
better than they could do formerly; and as bleaching in separate hanks
means that the cotton is kept in a more open form, and is thus more
easily penetrated by the various liquors which are used, it follows that
the bleach will be better and more thorough, which is what the bleacher
aims at. At the same time weaker liquors or, what is the same thing,
less material can be used, which means a saving in the cost of the
process. For bleaching yarn in the hank the following process may be
followed with good results:--

(1) Lye boil, using 1,000 lb. yarn, 40 lb. caustic soda of 70 per cent.,
and 50 lb. of soda ash of 58 per cent., giving five to six hours' boil
at low pressure.
(2) Wash through washing machine.
(3) Second lye boil, using 40 lb. soda ash of 58 per cent., and giving
two to three hours' boil, wash again through a washing machine.
(4) Chemic as in warp bleaching.
(5) Sour as in warp bleaching.
(6) Wash well.
(7) Hydro extract and dry.

Sometimes, if the yarn is to be sold in thread form, before the last
operation it passes through another, _viz._, treating with soap and blue
liquors, which will be dealt with presently.

The lye boils are done in the ordinary kiers, and do not call for
further notice, except that in filling the goods into the kiers care
should be taken that while sufficiently loose to permit of the alkaline
liquors penetrating through the hanks properly, yet they should be so
packed that they will not float about and thus become entangled and
damaged.

The washing is nowadays done in a special form of washing machine,
designed to wash the hanks quickly and well with as little expenditure
of labour and washing liquor as possible. There are now several makes of
these washing machines on the market, most of them do their work well,
and it is difficult to say which is the best. Some machines are made to
wash only one bundle at once, while others will do several bundles.
Generally the principle on which they are constructed is the same in
all, a trough containing the ash liquor, over which is suspended a
revolving reel or bobbin, usually made of wood or enamelled iron, the
bobbin being polygonal in form so that it will overcome readily any
resistance the yarn may offer and carry the hank