28 Cellulose 



thin films, it adheres with great tenacity to the surface upon 

 which it is dried. On treatment with water, however, the 

 cellulose film may be detached, and when freed from the by- 

 products of the reaction the cellulose is obtained as a homo- 

 geneous transparent colourless sheet or film, of great toughness, 

 which, on drying, hardens somewhat, increasing in toughness 

 and preserving a considerable degree of elasticity. From the 

 properties of the solution and of the cellulose regenerated from 

 it, it will be readily seen that both are capable of extensive 

 applications. 



QUANTITATIVE REGENERATION OF CELLULOSE FROM 

 SOLUTION AS THIOCARBONATE. Very careful experiments have 

 been made to determine the proportion of cellulose recovered 

 from solution as thiocarbonate. Weighed quantities of Swedish 

 filter paper were dissolved by the process, and the solutions 

 treated as follows : (a) Allowed to ' solidify ' spontaneously at 

 15-18. (b) Coagulated more rapidly at 55-65. (c) Sul- 

 phurous acid was added in quantity sufficient to combine with 

 one-third of the alkali present in the solution the resulting 

 solution being colourless : this was then set aside to coagulate 

 spontaneously. The regenerated celluloses were exhaustively 

 purified, by boiling in sodium sulphite solution, digesting in 

 acid, digesting in water, &c., and, repeating the treatments 

 until pure, they were finally dried for some days at 60 and 

 finished at 100. 



The following results were obtained : 



Weight of original cellulose Weight of regenerated cellulsse 



(a) 17335 I748o 



(6) 17415 I756o 



(f) 18030 1-8350 



The results show a net difference of 1*1 p.ct (increase), a 

 quantity which, for practical purposes, may be neglected. As, 

 however, the empirical composition of the regenerated cellulose 



