Preface to the New Edition ix 



yet sufficiently exactly determined to furnish a basis of positive 

 conclusions. This mode of resolution, however, establishes 

 another point of analogy with starch. So also reciprocally 

 does the production of the well-defined xanthogenic esters of 

 starch and their close general analogy with the better known 

 cellulose derivative Viscose. 



Nothing, however, in these results affects the evidence that 

 the actual configuration of the unit groups in the cellulose 

 complex is rather ketonic than aldehydic, nor the probability 

 that these groups are of cyclic type rather than of the normal 

 hexose character. 



In this connection the ascertained fluorescence of cellulose 

 [W. N. Hartley, Chem. Soc. J., 63, 243, (1893)], which is 

 intensified in some of its derivatives, and notably the acetates 

 (Cross & Bevan : J. Soc. Dyers, May, 1916), will be found, 

 when further investigated, to furnish some more direct 

 evidence on this point than that of processes of decomposition, 

 of which the effects as regards the cellulose complex are, in 

 important respects, problematical. Generally, it must be to 

 physical methods that we have to look for the full comple- 

 mentary interpretation of the related values furnished by 

 purely chemical methods. 



Separation and Estimation of Cellulose. As a 

 general result of research and criticism, the method of separa- 

 tion and purification of cellulose from cellulose mixtures, 

 described in our original volume, are confirmed and accepted. 

 A valuable review of work and literature on this section is that 

 of J. F. Briggs' * Recent Progress in the Analysis of Cellulose 

 and Cellulose Derivatives ' : Analyst, V. 40 (1915), pp. 107-120. 

 This author gives full value to M. Renker's critical study 

 of methods, ' Ueber Bestimmungsmethoden der Cellulose ' 

 (Berlin, 1 909). It is only necessary to add that, in dealing with 



