Compound Celluloses 



133 



The following results of experiments (Miihlhauser) may be 

 cited. The fibre-substance was purified previously to nitration 

 by boiling in alkaline solution (i p.ct. NaOH), thorough wash- 

 ing, and drying at 100. The acids used in nitration were 

 of maximum strength. 



The results may be given in the form of a table as under : 



The products were purified by exhaustively washing, diges- 

 tion in dilute solution of Na 2 CO 3 , and again washing. 



An extended series of observations by the authors established 

 the following points : 



(1) A gradual increase in yield with increase in duration of 

 exposure to the nitrating acid (at ordinary temperatures) up to 

 5-6 minutes, the maximum of 145 p.ct. being then attained. 



(2) After that oxidation supervenes, soluble products are 

 formed, and the yield of insoluble nitrate diminishes. 



(3) The increase in yield again observed on prolonged 

 exposure is a secondary result of the decomposition, alcoholic 

 OH groups being liberated from combination and then taking 

 part in the reaction. 



A microscopic examination of the nitrated fibre (Miihl- 

 hauser) showed that nitration by prolonged exposure was 

 attended by resolution of the fibre-bundles into ultimate fibres, 

 and these showed a shrinkage in volume (diameter). 



With the view of testing the homogeneity of the product, 

 specimens were exposed to the graduated action of alkaline 



