The Typical Cellulose and the Cellulose Group 17 



An examination of the structureless cellulose regenerated from 

 solutions of cotton as alkaline thiocarbonate (see p. 29) shows an 

 important differentiation from the original cellulose (bleached 

 fibre). This form of cellulose, after careful purification, was found 

 to combine with the caustic alkalis in dilute solution, in much 

 larger proportion ; thus from solutions of 3-1 p.ct. Na 2 O the cellu- 

 lose removed, i.e. combined with, the alkali to the extent of 5-6 

 p.ct. of its weight. With the dilute acids, on the other hand, no 

 increased combination was observed. 



This phenomenon has been more recently studied from the 

 independent standpoint of thermal equilibrium. It has been 

 shown that when pure cotton is plunged into dilute solutions 

 of the acids and alkalis, liberation of heat takes place (Vignon). 

 The rise of temperature was found to be slow, and, under the 

 conditions chosen for the experiments, ceases after the lapse of 

 seven to eight minutes. The following are typical results in 

 calories per 100 grms. of cotton. 



It would appear from these results that cellulose has the 

 properties of a feeble acid, and of a yet feebler base. From 

 the comparative insignificance of the * affinities ' involved, it 

 might be inferred that they could have but a small determining 

 value in regard to the uses or applications of cellulose. Recent 

 researches, however, have shown that the combinations of 

 cellulose with colouring matters, i.e. the dyeing properties of 

 the fibre-substance, are largely dependent upon a play of 

 c affinities ' of this order and narrow range. Vignon concludes, in 

 fact, from a careful and exhaustive survey of dyeing phenomena, 

 including the action of mordants, that they depend chiefly upon 

 the interaction of groups of opposite chemical function, viz. 



C 



