268 Cellulose 



this has only been investigated in a preliminary way, as stated in 

 the text (p. 227), and an exhaustive study on these lines offers 

 a most promising field of research. 



INVESTIGATION OF RAW FIBROUS MATERIALS. 



These various processes admitting of quantitative observation 

 of results the results being the constants of the individual fibres 

 having been studied with raw materials of known composition, 

 and belonging to one or other of the groups, may be applied to 

 fibres of unknown composition, and to complex mixtures, in which 

 two or more of the compound celluloses are represented. The 

 investigation of fibres of unknown composition proceeds on the 

 following lines : (a) a general examination with reagents, to deter- 

 mine whether lignified or not ; (b] a general histological examina- 

 tion, determining its structural characteristics. A specimen is 

 boiled for some time in caustic soda solution (i p.ct. NaOH), then 

 teased out, and the ultimate fibres measured. The length of the 

 ultimate fibre is one of the most important criteria of value of 

 a fibre. Cross-sections are cut and examined, to determine the 

 general features of the fibre-bundle : the average number of fibres 

 in the bundle, the dimensions, and the divisibility of the bundle. 

 For a detailed account of these methods the student must read the 

 special treatises on the subject (p. 243). 



Proceeding with the chemical examination. If the microscope 

 has revealed the presence of cuticular tissues, the raw material 

 should be extracted with ether-alcohol in a continuous extraction 

 apparatus, and the quantity of extract determined. The residue is 

 treated for the estimation of cellulose by the methods previously 

 described. The attendant reactions must be carefully observed. 

 The percentage of cellulose is the most important of the chemical 

 constants. The quality of the cellulose should be noted. It 

 should be examined for resistance to further hydrolysis, and to 

 oxidising agents, e.g. Fehling's solution, permanganate, &c. On 

 these results, it is classified as of the cotton or normal group, the 

 jute or wood cellulose group, or the esparto and straw group. The 

 general character of the non-cellulose constituents will have 

 appeared from their reactions ; further evidence is obtained by 

 examining the solutions from the preliminary alkaline hydrolysis, 

 and from the hydrolysis following the chlorination process. The 



