89 



camphor. The intermediate zone would offer considerable experi- 

 mental difficulties, but the ground lias already been broken by Trouton 

 and Rankine-*. 



A complete examination of celluloid from tliis point of view would 

 include the viscosity in dilute solution, gradually increasing the 

 concentration until determination of Trouton 's coefficient of viscous 

 traction became practicable, and finally the rigidity, bulk elasticity, 

 and tensile strength as the celluloid gradually lost its solvent. In 

 all cases temperature effects would have to be studied, and the 

 comparison of rigidity and viscous traction at various temperatures 

 would be of particular value in the case of finished celluloid, while 

 the data as a whole could hardly fail to throw light on the problem of 

 the structure of viscous colloids. 



References. 



^ Vol. 1, p. 705 (1912 edition). The account given here is written by 

 Schiipphaus. 



2 " Technology of Cellulose Esters," Worden, Vol. VIII. 



3 Cross, Bevan & Jenks, Ber., 34, 2496; Hake & Lewis, J. S.C.I. , 24, 374 

 (1905). 



^ See, for example. Lunge, J. Amer. Chem. Soc, 23, 527 (1901), and many 

 others. 



5 Nathan, J.S.C.I., 28, 177 (1909). Note particularly (p. 185) the small 

 variation in nitrogen percentage (from 12-95 per cent, to 13-05 per cent, in a 

 year's work). 



* See Miles, Eng. Pat. 19,330 of 1905, on the solubility changes induced by 

 partial hydi-olysis. An extensive list of patents is given by Worden, J.S.G.I., 

 38, 370 T(1919). 



' Baker, Trans. Chem. Soc, 103, 1653 (1913). The viscosity of nitrocellulose 

 in various solvents follows the empirical law 7 = 70 (1+ac)'', in wliich 7 = 

 viscosity of solution, lyo = viscosity of solvent, c = concentration, a and k are 



d log r} 



constants depending on solute and solvent. The value of — t is convenient 



a c 



for comparing different solvents. 



8 Baker, Trans. Chem. Soc, 101, 1409 (1912). From the viscosity concen- 

 tration curves given by mixtures of ethers and alcohols, it appears that dissociation 

 of the latter takes place in such mixtui'es, but this dissociation is probably 

 associated with the formation of an ether-alcohol complex, and to this complex 

 the solvent power of these mixtures for nitrocellulose is due. 



» Eng. Pats. 14,655 and 14,656 of 1915. (Rintoul, Cross, & Nobel's Explosives 

 Co., Ltd.) The additions are of the order of 0.1 to 1 per cent., and enable the 

 mixture of nitrocellulose and nitroglycerine to be gelatinised without raising the 

 temperature. 



'* Since this report was written, an important paper on tlie subject has been 

 published by Gibson & McCall, J.S.C.I., 39, 172-176 T, (1920). They find that 

 the composition of the ether-alcohol mixture of optimum solvent power depends 

 on the nitrogen content of the nitrocellulose. 



1" Bramley, Trans. Chem. Soc, 109, 469 (1916). 



10. Price {Trans. Chem. Soc, 115, 1116 (1919)) has shown that the abnormality 

 of the volatility of cordite made with equal properties of acetone and ethyl 

 methyl ketone is not due to any abnormality of vapour pressure or density of 

 the mixed solvents. 



^'- Thorpe, Dictionary of Applied Chemistry, loc. cit. 



^- Unpublished observation. Only dilute solutions have been examined.. 



" Dubosc, Le Caoutchouc et la Gutta-Percha, 9803-9808 (1919). 



" 1st Report, King 20-38, Chrystall 82-84. 

 2nd Report, Harrison 54-61. 



^*' Gibson makes the same suggestion in a recent paper. Trans. Chem, See. 

 117, 482 (1920). 



