COMMERCIAL CELLULOSE PRODUCTS 163 



into cellulose alkali and carbon disulphide. Viscose solutions 

 are employed for sizing paper and in the manufacture of wall- 

 papers. 



Mixed with metallic dust and colouring matters, viscose 

 can be converted into an artificial leather, and may also be 

 employed for rendering canvas, waterproof and for making 

 cinematograph films, etc. 



Viscoid, which is congealed viscose, is a hard mass obtained 

 by mixing viscose with various substances and allowing the 

 mixture to decompose spontaneously and harden ; it is used 

 for mouldings, cornices, statuettes, etc.* 



Solid Spirit. The substance sold under this name is ob- 

 tained by pouring a solution of cellulose acetate in glacial 

 acetic acid into alcohol ; a white solid is produced which does 

 not melt, and burns when ignited without leaving any ash. 



Cellulose acetate, in which there are approximately five 

 acetyl groups to the C 12 'cellulose unit, is soluble in acetone, and 

 is used largely as a dressing for the fabric of aeroplanl wings. 



Cellite is acetyl cellulose which is soluble in a mixture of 

 ethyl acetate and ethyl alcohol. Mixed with camphor it is 

 used in the manufacture of non-flammable cinematograph films. 



Willesden paper is paper waterproofed by treatment with 

 cuprammonia, whereby the fibres are gelatinized, and, when 

 dry, are impervious to water. 



Finally, mention may be made of a few substances which 

 are made from cellulose as a starting point, but which are 

 produced only by the profound decomposition of the molecule. 

 Thus by heating cellulose with a strong solution of caustic 

 potash and soda, oxalic acid is produced, and by the de- 

 structive distillation of wood, acetic acid, acetone and methyl 

 alcohol are obtained. 



MICROCHEMICAL REACTIONS. 



A. Normal Cellulose. 



I. With a dilute solution of iodine a yellow coloration 

 results. 



* See Bersch : " Cellulose, Cellulose Products and Artificial Rubber," Phila- 

 delphia, 1904. 



U * 



