46 Cellulose 



On emerging, therefore, the solution is at once coagulated to a 

 transparent jelly, and of considerable toughness. On applying 

 a slight pull to the jelly, grasped with the fingers or forceps, a 

 thread is produced ; and on fixing the end to a light wheel re- 

 volving at a definite rate, the thread is drawn off continuously 

 of uniform diameter. Several threads being twisted together 

 in the usual way of ' silk-throwing,' the artificial textile thread 

 is produced. After being deprived of water of hydration the 

 threads acquire the high white lustre of ' boiled-off' silk. 



In this state, however, it is the explosive nitrate, containing 

 11-12 p.ct. N. To fit it for consumption, therefore, the 

 ' silk ' is ' denitrated ' by treatment with ammonium sulphide 

 in the cold. This process in no way affects the lustre of the 

 thread, and when properly carried out gives a product not more 

 inflammable than ordinary cotton. 



The * artificial silk ' has been found to have a tensile 

 strength equal to 70 p.ct. of that of the natural product, of 

 the same degree of fineness. Its elasticity is inferior in about 

 the same proportion ; but it has a higher lustre and is pro- 

 duced at much less cost. It appears, therefore, capable of 

 considerable industrial use. 



OTHER DECOMPOSITIONS OF THE CELLULOSE NITRATES. 

 In addition to the explosive resolution into gaseous products, 

 of these cellulose esters, they are susceptible of a more gradual 

 process of decomposition, into which they pass spontaneously 

 under certain conditions yielding a complex of products, 

 some of low molecular weight, e.g. carbonic, formic, oxalic, 

 saccharic, and nitroxy -acids ; others of closer relationship to 

 the original cellulose, gummy acid bodies which have been 

 described as belonging to the pectic series. Observations of 

 these decompositions have been made by various chemists 

 (Maurey, Bechamp, Kuhlmann, Pelouze, De Luca, Compt. 

 Rend. 28, 343; 37, 134; 42, 676; 59, 363; 59, 487; 



