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, fleecy mass which is 

 highly absorptive. This is extensively employed in medicine 

 and surgery under the name "absorbent cotton." Like the 

 best paper it is nearl}^ pure cellulose. ]\Iany 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 

 alcohol. 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 



