264 Cellulose 



Bevan, J. Chem. Soc. 1889, 199). Instead of the bulb there 

 described as blown on the end of a tube, a simpler method 

 consists in blowing a thin bulb and inserting the prepared fibre, 

 and after insertion, drawing of the bulb. It is then placed in the 

 reaction flask, containing an atmosphere of chlorine. The flask or 

 bottle is closed with a cork well covered with paraffin, and bored 

 with one hole to admit the glass tube connecting with the 

 measuring apparatus. When the levels are all adjusted, the bulb 

 is broken by a blow against the side of the bottle. For further 

 particulars see the paper above cited, also for the estimation of 

 the hydrochloric acid formed. The cellulose estimation, by boiling 

 the chlorinated fibre with sulphite of soda solution, &c., and 

 washing off, has been already described (see p. 95). 



(c) Nitric acid process. The weighed fibre is placed in a flask, 

 and digested with 5 p.ct. nitric acid at 60. The gaseous products 

 may be collected and examined. Digestion is continued until the 

 yellow colour which at first results gives place to white. If 

 arrested at an earlier stage the residues of non-cellulose may be 

 removed by treating with weak alkaline solution. The cellulose 

 is washed, treated with dilute acid, again washed, and dried for 

 weighing. The yield is from 60-66, considerably less, therefore, 

 than by either of the above methods. 



In reference to the theory of the action, show that by adding urea 

 the specific action of the acid is entirely arrested, and it becomes 

 similar to that of hydrochloric acid or sulphuric acid dilute. The 

 specific action also has a limit in reference to the concentration 

 of the acid, which must contain at least 3 p.ct. HNO S . 



(d) Chromic acid process. This process should be investigated 

 with chromic acid only, and with the addition of acetic acid and of 

 sulphuric acid. In the first case, the action is extremely slow, and 

 there is considerable combination of the oxide with the fibre- 

 substance. The presence of the hydrolysing acid causes the 

 specific oxidation of the non-cellulose constituents. In dilute 

 solution this takes place without evolution of gas. The product 

 may be tested from time to time by washing off a small portion, 

 exposing to chlorine, and afterwards plunging into sodium sulphite 

 solution. When this reaction ceases, arrest the experiment, wash 

 off the product, dry, and weigh. After weighing, compare this oxy- 

 cellulose mixture with the celluloses obtained by the above 



