MR. EDWARD SCHUNCK ON COTTON-FIBRE. 95 



IV. On some Co7istituents of Cotton-fibre. 

 Bv Edward Schunck, Ph.D., F.R.S. 



Read February 4th, 1868. 



It is generally supposed that cotton-fibre, when quite pure, 

 consists entirely of woody fibre, or cellulose, and that its 

 composition is consequently represented by the formula 

 CjjHjqOjo. It is certain, however, that in the raw state, 

 as furnished by commerce, it contains a number of other 

 substances, some of which occur so constantly that they 

 may be considered essential constituents of cotton, viewed 

 as a vegetable product. The object of the bleaching pro- 

 cess to which most cotton fabrics are subjected, is to de- 

 prive them of the impurities which are either natural to 

 the fibre itself or have been introduced, accidentally or 

 designedly, during the process of manufacture. Notwith- 

 standing the importance of an accurate knowledge of every- 

 thing connected with this staple, from an industrial point 

 of view, I cannot find that the substances existing along 

 with cellulose in cotton-fibre have ever been subjected to 

 a special chemical examination; and all that is known 

 about them may therefore be stated in a few words. 

 Persoz"^ says that the woody fibre constituting the tissues 

 of cotton, hemp, linen, &c. is not pure ; it contains : — 



1. A certain quantity of colouring-matter, which is 

 more or less protected from the action of decolourizing 

 agents by the bodies which accompany it, naturally or 

 accidentally. 



2. A peculiar resin, insoluble in water and not easily 

 soluble in alkalies, which plays the part of a reserve, and 

 protects the colouring-matters inherent in the fibre from 

 the action of the agents which ought to destroy and re- 

 move them. 



* Traite de I'lmpression des Tissus, t. ii. p. 20. 



