Manchester Memoirs, Vol. Ixv. (192 1), No. 12 



XII. — Theory of the Solvent Action of Aqueous Solutions of 

 Neutral Salts on Cellulose. 



By Herbert E. Williams. 



(Bead April 12th, 1921. Received for publication September 20th, 1921.) 



The object of this paper is to demonstrate that the solution 

 of cellulose in certain aqueous solutions of neutral salts is 

 largely a physical phenomenon, chemical reaction playing but 

 a small part ; that it is independent of the chemical nature of 

 the salt, but that it depends directly on certain physical 

 properties of the concentrated salt solution, and on the power 

 of the salt to form hydrates in solution. 



During a research on the preparation and properties of the 

 metallic thiocyanates and their double salts, it was noticed 

 that the concentrated solutions of several of these salts had a 

 profound action on paper. Several years later attention was 

 again directed to this subject, and a systematic study of the 

 action of the concentrated solutions of the thiocyanates on 

 cellulose was undertaken. A number of pure thiocyanates 

 were prepared, and the action of their concentrated solutions 

 on cellulose carefully observed, both in the cold and on 

 heating. As the action on cellulose varied a little with the 

 particular form of cellulose used, and the treatment it had 

 undergone, the experiments described in this paper were 

 carried out with chemical wood pulp taken from the same 

 bulk sample ; thus insuring a cellulose of a uniform condition. 



The solvent action of the solution was determined by 

 suspending a small portion of the chemical wood pulp in the 

 solution and allowing the mixture to evaporate by slow boil- 

 ing. A sample was taken out from time to time and examined 

 on a glass slide under the microscope, and the temperature of 

 the boiling point of the solution noted when fibre structure 

 was no longer visible and the drop on the slide appeared 

 perfectly uniform and homogeneous. The solution was then 

 diluted and the precipitated cellulose washed and examined 



October 31st, 1921. 



