viii Preface to the New Edition 



below the standard of ' normal cellulose.' It is necessary to 

 note this in view of the common assumption that chemical 

 filter-paper or ' Surgical Cotton Wool ' is a cellulose hors 

 concours, and may be taken as a ' pure cellulose ' for important 

 investigations, fulfilling the comprehensive definition of the 

 'normal pure cellulose/ viz., a bleached and otherwise 

 purified cotton which can be 'mercerised' without loss of 

 weight, and thereafter converted into Xanthogenic ester, dis- 

 solved as Viscose, and regenerated to Cellulose (Hydrate), also 

 without loss of substance. 



The nearest approach to the normal, as thus defined, in the 

 form of an easily accessible material is the ' Madder bleached ' 

 cotton fabric of the calico printer, which may be used in 

 investigations, as such, or may be previously disintegrated by 

 mechanical means to the state of relatively ' loose fibre.' 



Cellulose Constitution. That the normal cellulose 

 is resolved by hydrolysis quantitatively into dextrose, was a 

 statement of the text-books which remained for years on the 

 basis of quite insufficient experimental proof (see p. 49). The 

 re-investigation by Ost (Researches, iii., pp. 39-43) of the 

 hydrolysis by solution in sulphuric acid (H 2 SO 4 .2H 2 O 

 H 2 SO 4 .3H. 2 O) and afterwards diluting and boiling the 

 process originally employed by Flechsig has carried the 

 resolution to satisfactorily extreme limits, and supplied the 

 identification of the product, by more modern methods, as, 

 in effect, a homogeneous hexose, viz., dextrose. 



The process of resolution by acid in a medium of acetic 

 anhydride with attendant acetylation (//</., pp. 43-47), has 

 given us the cellobiose, and a special cleavage of the cellulose 

 complex which is destined to be of great value in investigating 

 the constitution of the typical cellulose, and of other celluloses 

 by comparison. The quantitative results are, however, not 



