76 Cellulose 



they either exist in combination as in the acetals or are 

 susceptible of an alternative form, the carbonyl becoming 

 hydroxyl oxygen. 



(3) Complete proximate resolution, by { fusion' with alkaline 

 hydrates, into hydrogen, carbonic, oxalic, and acetic acids. 

 The yield of the latter tending to a maximum of 30-35 p.ct. 

 indicates that the grouping CO CH 2 is an important element 

 in the constitution of the unit groups. 



(4) Negative characteristics. These are (a) those which 

 characterise generally the saturated compounds in which 

 group cellulose must be classified, (b) Resistance to alkaline 

 hydrolysis, (c) Resistance to oxidising actions up to a certain 

 limit of intensity, (d) Resistance to acetylation : requiring 

 either very high temperature or the presence of an auxiliary 

 (ZnCl 2 ) for the determination of reactions of its OH groups 

 with the acid oxide. 



(5) Synthetical reactions. Of these the more definite are 

 those which yield the esters, viz. nitrates, acetates, and ben- 

 zoates. The highest nitrate obtainable appears to be the tri- 

 nitrate (hexanitrate in the C 12 formula) ; the highest acetate the 

 tetracetate (C 6 formula). A higher degree of acetylation has 

 been obtained, but there is undoubted evidence that this results 

 from molecular resolution (hydrolysis). The conclusion to 

 be drawn from the relationship of these esters to the parent 

 molecule is that, of five O atoms in the formula C 6 H 10 O 5 , four 

 react as OH oxygen with retention of the original configura- 

 tion of the molecule. 



The thiocarbonate reaction further elucidates the functions 

 of the OH groups, and the resistance of the molecule to hydro- 

 lysis. It constitutes a further distinction of the celluloses from 

 starch, as a type of molecular configuration ; starch failing to 

 give any definite indications of this reaction, and, in contrast to 

 cellulose, being eminently susceptible of hydrolytic resolution. 



