228 INDUSTRIAL PLANTS 
highest importance. It favors the interlocking of the fibers 
in spinning and thus makes possible yarns which combine 
in a wonderful way extreme fineness, softness, and strength. 
No other fiber has this peculiar twist. Of all others the wool 
of sheep, from its curliness, most nearly resembles cotton, 
which indeed well deserves to be called “ vegetable wool.” 
The separation of the fiber from the seed after picking is 
accomplished by a machine called a gin which either pulls 
the seed from the fiber by means of rollers, or tears away the 
fiber by the action of notched wheels revolving rapidly be- 
tween the bars of a grating too narrowly set for the seeds 
to pass through. The ginned fiber is ready for spinning 
after various machines have removed impurities, and combed 
the fibers approximately parallel. After spinning, the yarn 
is bleached, or dyed if necessary, and may be then twisted 
into thread or other cordage, or may be woven or otherwise 
made into a fabric. The cleaned fiber rolled into sheets is 
cotton batting, widely used for filling. In their crude state, 
cotton fibers are covered with an oily varnish which repels 
water. When this layer is removed and the fibers thoroughly 
cleansed there is obtained a white, fleeey mass which is 
highly absorptive. This is extensively employed in medicine 
and surgery under the name “absorbent cotton.” Like the 
best paper it is nearly pure cellulose. Many of the finer 
sorts of paper are made from cotton rags, waste from spin- 
ning mills, and fibers too short to spin. 
Absorbent cotton treated with nitric and sulphuric acids 
becomes converted into nitrocellulose or guncotton. An in- 
timate mixture of this with laurel camphor forms celluloid. 
Collodion is a form of nitrocellulose dissolved in ether and 
aleohel. Artificial silk is made by forcing collodion through | 
exceedingly fine openings into running water, where the 
collodion at once hardens into a silky fiber, which after 
thorough washing becomes well adapted to the same uses 
as natural silk. The carbon filaments of incandescent elec- 
tric lamps are charred cotton threads or sometimes car- 
bonized strips of paper pulp. Cotton is the fiber chiefly 
used also for candle and lamp wicks. 
68. Bast fibers form, generally speaking, the strongest 
