caustic soda and sulphuric acid whereby they are made stronger
and heavier, and given a silky luster and feel. The luster produced
upon cotton is due to two causes, the change in the structure of the
fiber, and the removing of the outer skin of the fiber. The swelling
of the fiber makes it rounder, so that the rays of light as they fall
upon the surface are reflected instead of being absorbed. The quality
and degree of luster of mercerized cotton fabrics depends largely
upon the grade of cotton used. The long-staple Egyptian and Sea Island
cotton, so twisted as to leave the fibers as nearly loose and parallel
as possible, show the best results. If the yarn is singed the result
is a further improvement. Yarns and fabrics constructed of the
ordinary grades of cotton cannot be mercerized to advantage. The cost
of producing high-grade mercerized yarn is about three times that of
an unmercerized yarn of the same count, spun from the commoner
qualities of cotton.

Mercerized yarn is employed in almost every conceivable manner, not
only in the manufacture of half-silk and half-wool fabrics, and in
lustrous all-cotton tissues, but also in the production of figures and
stripes of cotton goods having non-lustrous grounds. Mercerized yarn
used in connection with silk is difficult to detect except by an
expert eye.

=Characteristics of a good piece of Cotton Cloth.= A perfect cotton
fiber has little convolutions in it which give the strong twist and
spring to a good thread. In this respect the Sea Island cotton is the
best. There are five things requisite for cotton cloth to be good,
viz.:

1. The cloth must be made of good fiber, that is ripe and long.

2. The fiber must be carefully prepared. All the processes must be
well performed--for the very fine thread fiber must be combed to
remove poor fiber. The combing, however, is not always done.

3. The warp and woof threads must be in good proportion.

4. The cloth must be soft, so that it will not crease easily.

5. It must be carefully bleached--the chemicals used must not be
strong.

CHAPTER XII

KNITTING

The art and process of forming fabrics by looping a single thread,
either by hand with slender wires or by means of a machine provided
with hooked needles, is called knitting. Crocheting is an analogous
art, but differs from knitting in the fact that the separate loops are
thrown off and finished by hand successively, whereas in knitting the
whole series o