10 Cellulose 



10-15 p.ct. s * Ammonia (NH 3 ) 

 2-2-5 .... Copper (as CuO) 



(1) To a solution of a cupric salt, ammonium chloride is 

 added, and then sodium hydrate solution in sufficient excess ; 

 the blue precipitate is thoroughly washed upon a cloth filter, 

 squeezed, and re-dissolved in ammonia solution of 0^92 

 sp.gr. 



(2) Thin sheet copper is crumpled up, placed in a glass 

 cylinder and covered with strong ammonia. Atmospheric air 

 is drawn by aspiration so as to bubble through the liquid 

 column at such a rate as to amount per hour to about forty 

 times the volume of liquid used. In about six hours a solution 

 is obtained of the composition given above (C. R. A. Wright). 



Under the latter conditions the action of the solution upon 

 the cellulose may be made simultaneous with its production. 

 For this the cellulose and metal are mixed together as inti- 

 mately as possible and exposed as described to the action of 

 aqueous ammonia and oxygen. 



There are various ways of accelerating the preparation of the 

 cuprammonium solution from the metal. Thus, as compressed 

 oxygen is now an ordinary commodity it is easy to substitute the 

 pure gas for the atmospheric mixture, with the result that the 

 volume of gas passing through the solution may be considerably 

 reduced, and therefore the loss of ammonia lessened. 



The oxidation of the copper is facilitated by contact with a metal 

 which is ' negative ' to the copper in presence of ammonia ; or this 

 differential disposition of the copper to be attacked may be more 

 directly attained by means of the electric current, the copper to be 

 attacked being brought into conducting connection with the 

 negative, and the second metal with the positive pole of a battery 

 the latter being inserted in a porous pot within the alkaline 

 liquid (Hime and Noad, English Patent 7716/89). 



The solutions of cellulose in cuprammonium are of little 

 stability, the cellulose being readily precipitated by the 



