312 Cellulose 



then acetylated under identical conditions of treatment with 

 acetic anhydride, diluted with glacial acetic acid and in 

 presence of sulphuric acid, as catalyst, added in proportion 

 of 15 p.ct. weight of the weight of the cellulose. It was ob- 

 served that (b) was rapidly attacked, swelling progressively, and 

 after 20 hours the reaction was visibly complete ; (#), on the 

 other hand, remained for several hours unchanged in appear- 

 ance, and even after the 20 hours the mass was visibly fibrous. 

 After precipitating with water with the usual precautions for 

 obtaining the products in the free flocculent form, the following 

 quantitative results were obtained : 



(a) (b) 



Yield of acetate 128-3 168-3 



On saponification p.ct. of acetate 



Cellulose 68 -5 59-4 



Acetic acid 39-9 53-4 



It is evident that in the case of (a) there is a breakdown 

 to water-soluble derivatives, simultaneous with the lower degree 

 of actual esterification. 



Similar results have been obtained by acetylating with zinc 

 chloride as catalyst. We have previously called attention to 

 the striking difference in the reactions of raw cotton with 

 sodium hydrate and carbon bisulphide (viscose reaction) as 

 compared with bleached cottons (' Researches,' i. 28-29). These 

 differences, however, might be ascribed on the evidence to the 

 mere presence or absence of the non-cellulose constituents 

 characteristic of the raw cotton. It was not proved that the 

 bleached cotton was a constitutionally changed cellulose. It 

 is now clear that since water only determines fundamental 

 change, the change will be intensified and varied by the presence 

 of hydrolytic agents, alkaline or acid. And generally we may 

 affirm (i) that cellulose is constitutionally modified by any and 

 every treatment with reagents ; (2) that profound changes 

 affecting the reactivity of its individual groups are determined 



