from the plant. Thus the ultimate fibres of jute are really very
short--from 1/10 to 1/8 of an inch in length; those of flax are somewhat
longer. Jute, flax, China grass and hemp are common fibres which are
derived from the bast of the plants.

There is an important point of difference between seed fibres and bast
fibres, that is in the degree of purity. While the seed fibres are
fairly free from impurities--cotton rarely containing more than 5 per
cent.--the bast fibres contain a large proportion of impurity, from 25
to 30 per cent. as they are first obtained from the plant, and this
large quantity has much influence on the extent and character of the
treatments to which they are subjected.

As regards the structure of the fibres, it will be sufficient to say
that while seed hairs are cylindrical and tubular and have thin walls,
bast fibres are more or less polygonal in form and are not essentially
tubular, having thick walls and small central canals.

=The Cotton Fibre.=--The seed hairs of the cotton plant are separated
from the seeds by the process of ginning, and they then pass into
commerce as raw cotton. In this condition the fibre is found to consist
of the actual fibrous substance itself, containing, however, about 8 per
cent. of hygroscopic or natural moisture, and 5 per cent. of impurities
of various kinds, which vary in amount and in kind in various
descriptions of cotton. In the process of manufacture into cotton
cloths, and as the material passes through the operations of bleaching,
dyeing or printing, the impurities are eliminated.

=Impurities of the Cotton Fibre.=--Dr. E. Schunck made an investigation
many years ago into the character of the impurities, and found them to
consist of the following substances:--

=Cotton Wax.=--This substance bears a close resemblance to carnauba wax.
It is lighter than water, has a waxy lustre, is somewhat translucent, is
easily powdered, and melts below the boiling point of water. It is
insoluble in water, but dissolves in alcohol and in ether. When boiled
with weak caustic soda it melts but is not dissolved by the alkali; it
can, however, be dissolved by boiling with alcoholic caustic potash.
This wax is found fairly uniformly distributed over the surface of the
cotton fibre, and it is due to this fact that raw cotton is wetted by
water only with difficulty.

=Fatty Acids.=--A solid, fatty acid, melting at 55 deg. C. is also present
in cotton. Probably stearic ac