251
40. Hydro-extractor 252
41. Automatic Yarn-dryer 253
42. Truck Yarn-dryer 254
43. Drying Cylinders 255
44. Experimental Dye-bath 263

CHAPTER I.

STRUCTURE AND CHEMISTRY OF THE COTTON FIBRE.

There is scarcely any subject of so much importance to the bleacher,
textile colourist or textile manufacturer as the structure and chemistry
of the cotton fibre with which he has to deal. By the term chemistry we
mean not only the composition of the fibre substance itself, but also
the reactions it is capable of undergoing when brought into contact with
various chemical substances--acids, alkalies, salts, etc. These
reactions have a very important bearing on the operations of bleaching
and dyeing of cotton fabrics.

A few words on vegetable textile fibres in general may be of interest.
Fibres are met with in connection with plants in three ways.

First, as cuticle or ciliary fibres or hairs; these are of no practical
use, being much too short for preparing textile fabrics from, but they
play an important part in the physiology of the plant.

Second, as seed hairs; that is fibres that are attached to the seeds of
many plants, such, for instance, as the common thistle and dandelion;
the cotton fibre belongs to this group of seed hairs, while there are
others, kapok, etc., that have been tried from time to time in spinning
and weaving, but without much success. These seed hairs vary much in
length, from 1/4 inch to 1-1/2 inches or even 2 inches; each fibre
consists of a single unit. Whether it is serviceable as a textile fibre
depends upon its structure, which differs in different plants, and also
upon the quantity available.

The third class of fibre, which is by far the most numerous, consists of
those found lying between the bark or outer cuticle and the true woody
tissues of the plant. This portion is known as the bast, and hence these
fibres are known as "bast fibres". They are noticeable on account of the
great length of the fibres, in some cases upwards of 6 feet, which can
be obtained; but it should be pointed out that these long fibres are not
the unit fibres, but are really bundles of the ultimate fibres
aggregated together to form one long fibre, as found in and obtained