Manchester Memoirs, Vol. Ixv. (192 1), No. 12 13 



sidered as water in which two hydrogen atoms are replaced 

 with two ethyl groups, is practically insoluble in water, and 

 in calcium thiocyanate solution up to a concentration of 

 Sp. Gr. 1.36 which corresponds with the hydrate 



Ca(CNS) 2 ioH 2 0, 



but dissolves in increasing quantities in the cold solution of 

 greater concentration. With a solution of Sp. Gr. 1.4 corres- 

 ponding to the hydrate Ca(CNS) 2 8H 2 nearly an equal 

 volume of ether is dissolved, and moreover it is a remarkable 

 fact that the amount of ether dissolved is equivalent to the 

 water lost from the decahydrate, molecule for molecule. The 

 amount dissolved corresponds to the formula 



Ca(CNS) 2 8H 2 02(C 2 H 5 ) 2 0. 



Conclusion. 



The solution of cellulose in an aqueous solution of a 

 neutral salt is independent of the chemical nature of the salt, 

 but is largely dependent upon the physical properties of the 

 salt solution. For such a solution to dissolve cellulose it 

 must consist of a liquid hydrate — an associated molecular 

 complex of salt and water. But this complex must be of such 

 an order that it has a viscosity above a certain minimum, and 

 a positive heat of dilution between well defined limits. 



These limiting conditions will vary according to the nature 

 of the cellulose, and the treatment which it has previously 

 undergone ; but for any particular cellulose the limits will be 

 constant for all salt solutions in water. 



Our thanks are due to the Renwil Syndicate for permission 

 to publish this work, to Mr. C. F. Cross for the kind interest 

 he has taken in this research, and to Dr. H. F. Coward for 

 reading through the paper before publication. 



Since this work was accomplished, our attention has been 

 drawn to the work of Dubosc (1) in France' and of P. von 

 Weimarn (2) of Russia. 



Dubosc claimed the solution of cellulose in the aqueous 

 solutions of sodium and potassium thiocyanate. Working 

 on the method described in the course of this paper no 

 solution of the cellulose was obtained in either sodium or 

 potassium thiocyanate solutions ; and such a solution seems 

 unlikely under these conditions, at least for an unmodified 

 cellulose. 



