308 Cellulose 



know of cellulose in aqueous solution as thiocarbonate ^p. 25), 

 its 'gratuitous ' character becomes still more prominent. The 

 nitric groups are merely a factor of a particular process of 

 solution of cellulose; they do not modify in any essential 

 respect the properties of the parent molecule, but render these 

 available by bringing the cellulose into a condition of homo- 

 geneous solution. Lehner's ' artificial silk ' process illustrates 

 these considerations in a very direct way. For the spinning of 

 the thread the solution as nitrate is necessary ; but the sub- 

 sequent process of denitration changes the physical properties 

 of the product in so small a degree as to escape detection 

 otherwise than by the application of special tests. The pro- 

 ducts known as celluloid, xylonite, &c., are not subjected to 

 any denitration process ; but the cellulose products obtainable 

 by means of the cellulose xanthate are so similar to these that 

 the plastic properties of cellulose itself are more than ever 

 apparent as the essential basis of these manufactures. The 

 same facts are illustrated by the acetates of cellulose. When 

 these are prepared under carefully regulated conditions they 

 exhibit the same properties in solution as the nitrates, i.e. high 

 viscosity and coalescence, on evaporation of the solvent, to a 

 homogeneous elastic solid. It is evident, therefore, that the 

 nitrates of cellulose in such uses will be subjected to the ordeal 

 of a severe competition, and in certain directions must be dis- 

 placed by the parent substance itself or by derivative com- 

 pounds at present known or yet to be discovered. 



The manufacture of explosives composed exclusively or partly 

 of the cellulose nitrates is now an industry of enormous pro- 

 portions. For many years after the introduction of gun-cotton 

 as an explosive its application was limited by its denomination 

 as a 'high explosive,' i.e. for blasting and similar purposes. 

 The researches of later years have shown that by changing the 

 physical condition of these ' high explosives ' their explosive 



