The Typical Cellulose and the Cellulose Group 8 1 



considerable loss of weight of flax cloth in bleaching (20-30 p.ct.) 

 falls mainly in the early alkaline treatment, the chief difficulties 

 are in the breaking down of the more resistant bodies derived 

 from the cuticle, including chlorophyll. 



The celluloses of this group thus purified may be taken 

 as chemically identical with cotton cellulose, investigation 

 having so far failed to differentiate them. It must be noted, 

 however, that the several members of the group present dis- 

 tinct morphological characteristics, and differ also in such 

 external properties as lustre and 'feel.' These are in part 

 correlated with the differences in minute structure, but they are 

 no doubt in part differences of substance. So far, however, 

 we have no knowledge of the proximate constitution of these 

 substances, and can therefore say nothing as to the causes of 

 difference in this respect. 



On the other hand, the essential identity of these cellu- 

 loses is established in regard to ultimate composition and in 

 reference to the following properties and reactions : 



(1) Resistance to hydrolysis and oxidation, and other nega- 

 tive characteristics, indicating a low reactivity of the CO and 

 OH groups. 



(2) Their relationships to the special solvents previously de- 

 scribed, including the thiocarbonate reaction. 



(3) Formation of esters, nitrates, acetates, benzoates. 



Of the above, it is sufficient in general laboratory practice 

 to examine cellulose in regard to ultimate composition, resist- 

 ance to alkaline hydrolysis, behaviour with solvents, and re- 

 actions with sulphuric acid (solution without blackening) and 

 nitrating mixture (H 2 SO 4 and HNO 3 ) ; the ' nitration ' pro- 

 ceeds without oxidation, and gives a higher yield of product, 

 160-180 p.ct. according to the condition. 



Group (b). These celluloses are differentiated from the 

 former group (i) by ultimate composition, the proportion of 



G 



