Compound Celluloses 105 



found to be in excess of the half, as a result of oxidising actions. 

 This point should be borne in mind. 



(3) Control observations. (a) The chlorine in combina- 

 tion in the chlorinated fibre may be directly estimated by any 

 of the standard methods by which the * organic ' molecule is 

 broken down and the chlorine liberated as hydracid. 



The chlorinated fibre itself is, for obvious reasons, some- 

 what difficult to deal with. The chlorinated product may be 

 dissolved by treatment with pure sodium hydrate, by which 

 treatment it is largely decomposed. To complete the isolation 

 of the chlorine as sodium chloride, the solution and washings 

 are boiled down to dryness, and heated for some time at 200- 

 300 C. An iron dish may be used for this treatment. The 

 soluble chloride is dissolved out and precipitated as silver 

 chloride, in presence of nitric acid. 



(b) The cellulose may be isolated in the usual way, by boiling 

 the fibre-substance with sodium sulphite solution, and further 

 treating the cellulose as described, p. 95. The resulting solution 

 and washings of the cellulose may also be employed for the 

 estimation of the chlorine, the organic products being destroyed 

 by oxidation with nitric acid. Sufficient silver nitrate being 

 previously added, the oxidation may be carried out in an open 

 flask attached to an upright condenser. 



The chlorination has also been studied in a different way, (i) 

 for the estimation of the total chlorine combining ; and (2) for 

 proving that no destructive oxidation takes place. 



Weighed quantities of the fibre-substance were chlorinated (a) 

 after boiling in water, (V) after boiling in i p.ct. NaOH solution. 

 Duplicate specimens were weighed after these treatments and 

 without chlorination, and the statistics are worked out upon the 

 weights of the fibre- substance after treatment. After chlorination 

 the products were transferred to a bell jar containing an ample 

 supply of solid potassium hydrate ; the vessel was exhausted, and 

 the fibrous products left for some days. After a second similar 

 exposure in vacuo over solid KOH, and with addition of sulphuric 



