Compound Celluloses 107 



of the fibre-substance, acetic acid is formed. The maximum 

 yield is obtained in the process of decomposing by digestion 

 with dilute nitric acid. As it is also formed in considerable 

 quantity by dissolving the fibre in sulphuric acid, in the cold, 

 and obtained from the solution by diluting and distilling, it 

 must, in such case, be regarded as a product of hydrolysis, and 

 not of oxidation of the lignocellulose. The problem of its 

 constitutional relationship will be discussed in due course. 

 The estimation of the acid in the latter case need not be dealt 

 with, but it is necessary to describe the method by which it is 

 estimated after being liberated by the nitric acid treatment. 

 The weighed quantity of fibre is placed in a flask and treated 

 with 4 times its weight of 5 p.ct. nitric acid. It is digested for 

 5-6 hours at 90, with the flask heated in a water-bath, and 

 attached to an upright condenser. The lignone being entirely 

 resolved, the acid solution is poured off, and the fibrous residue 

 washed with hot water. It is then digested with 5 p.ct. of its 

 weight (original fibre) of sodium carbonate dissolved in a small 

 quantity of water, which completes the removal of the lignone 

 derivatives from the residual cellulose. The solution and 

 washings are added to the original acid liquid. It is now 

 necessary to destroy the residues of nitric acid before distilling 

 for the volatile acid. A small quantity of sulphuric acid is 

 added to the liquid, in a flask, which is then digested for some 

 hours upon metallic iron. The solution is then boiled for 

 some time, with the flask attached to an upright condenser. 

 Urea is then added, and the solution distilled, taking care that 

 the sulphuric acid is present in slight excess. For the complete 

 removal of the acetic acid it is necessary to distil over as much 

 of the contents of the flask as possible, and to repeat the 

 distillation at least twice, adding a certain volume of water to 

 the flask, and taking over an equal volume of the distillate. 

 The distillate is then made up to a definite volume and 



