4 INTRODUCTORY 



reference should be made to other treatises, such as 

 Matthews' Textile Fibres and Wiesner's Die Rohstoffe 

 des Pflanzenreichs. A general method for preparing 

 the ultimate fibres for the measurement of their length 

 and diameter is given for convenience at the end of 

 the following section. 



Chemical Examination. The chief constituent of vege- 

 table fibres is the substance known as cellulose, 

 which is composed of the three elements, carbon, 

 hydrogen, and oxygen, combined in the proportions 

 represented by the formula C 6 Hi O 5 . Associated with 

 this substance is a certain amount of water and a 

 small proportion of mineral matter. The cellulose does 

 not exist in fibres as a single definite compound, but 

 rather as a more or less complex product which may 

 be regarded as composed of a typical or true cellulose 

 with certain other groups. The cellulose of fibres may 

 thus be divided into two classes, (i) the pectocelluloses 

 and (2) the lignocelluloses. The pectocelluloses are 

 represented by the fibre substance of cotton, hemp, and 

 flax, and consist of the true or typical cellulose associ- 

 ated with so-called pectic bodies, which can be removed 

 by treatment with alkali. The lignocelluloses form the 

 fibre substance of such products as jute, Manila and 

 Sisal hemps, and wood, and consist of a complex of 

 true cellulose with lignone which itself is a complex 

 of certain simpler groups. 



One of the chief objects of the chemical examina- 

 tion of fibres is the determination of the character of 

 the cellulose and the proportion of true cellulose 

 present. The methods usually employed are based 

 on those described by Cross, Bevan, and King in their 

 Report on Indian Fibres and Fibrous Substances. The 

 following is a summary of the processes adopted, to- 

 gether with an indication of the manner in which the 

 results are interpreted. 



Moisture. The amount of moisture is determined 

 by drying a specimen at 100 iioC. It is to some 

 extent an index of the susceptibility of the fibre to 

 attack by hydrolytic agents. Textile fibres of the 

 highest class are distinguished by their relatively low 

 moisture content. Owing to the variation of this 



