54. REPORTS ON THE STATE OF SCIENCE.—1918. 
The fibres possess many physical properties in common with 
other colloids such as indiarubber and gelatine. 
When subjected to stress in a dry condition they become deformed 
and acquire increased double refracticn which persists when the 
stress is removed.!2 This inereased double refraction shows the 
presence of extra internal stresses resulting from the deformation. 
When placed in a solvent which tends to produce swelling—water 
in the case of fibres—these extra internal stresses disappear and the 
fibres regain their original shape. When compressed under boiling 
water most fibres become permanently deformed, no internal stresses 
being produced. 
These theoretical points have an important bearing on many of 
the phenomena met with in the treatment of textile materials. 
(A) Introduction. 
1 Von Weimarn, Grundzuge der Dispersoid chemie., Leipzig (1912). 
2,W. H. Bragg and W. L. Bragg, Proc. Roy. Soc. A. 8'7, 277 (1914), etc. See also 
Trans. Chem. Soc., p. 252 (1916). 
3 A. Smits and F. EH. C. Scheffer, Proc. K. Akad Wetlensch, Amsterdam, 19, 432 
1916). 
: 4A. Fock, Centr. Min. 392 (1916). 
5 J. Beckenkamp, ibid. 97 (1917). 
6 J. Stark, Jahr. Radioaktiv. Electonihk, 12, 280 (1915). 
7¥F Rinne, Zeit anorg. Chem., 96, 317 (1916). 
8 P. Pfeiffer, ibid., 92, 376 (1915) ; 97, 161 (1916). 
9H. M. Dawson, Annual Report Chem. Soc. (Physical Chemistry) (1917). 
0 J. Perrin, Brownian Movement and Molecular Reality. 
C0, F. Cross, Presidential Address to Soc. Dyers and Colourists, 34, 19 (1918). 
12 W. Harrison, Proc. Roy. Soc. A, 94, 460 (1918). 
13 JT. Langmuir, Journ. Amer. Chem. Soc., 28; 2221 (1916). 
M4 Tinker, Proc. Roy. Soc. A, 92, 357 (1916). 
15 W. Moeller, Koll. Zeit. 19, 205, 213 (1916) ; 20, 242, 257 (1917); 28, 11 (1918). 
16 J. R. Katz, Koll. Ch. Beith., 9,1 (1917). 
17 Bachmann. Koll. Zeit, 9, 312 (1911); 11, 150 (1912); 12, 204 (1913); 98, 85, 
(1918) ; also Zeit. anorg. Chem., 93, 125-172 (1911); 9, 202 (1912) ; 100, 76 (1917). 
18 Debye & Scherrer, Phys. Zeit., 18, 291 (1917). 
Cotton. 
Regarding the chemical constitution of the substance of the 
cotton fibre, six formule have already been proposed, but none of 
these have been established. (Refs. 1°16). é 
Cross originally held that the cellulose molecule was large, being 
composed of units of a certain type bound together ; Green favoured 
a simple formula. In a recent address (Ref. A.“) Cross stated that 
there are no grounds for the assumption of large molecules in the 
strict chemical sense. He considers that the celluloses are liquid 
systems capable of large volume changes and also solution-aggregates 
of amphoteric character. He suggests that the units in the cellulose 
aggregate may have dimensions less than C, One difficulty in the 
way of the acceptance of a very simple formula for cellulose is the 
number of hydroxyl groups which chemical methods prove to be 
present ; all the bodies of the same chemical composition, known up 
to the dimension C;, having a corresponding number of hydroxyl 
groups are soluble in water. 
It is quite likely that the units in the cellulose aggregate are 
bound together in a similar manner to the units in a crystal, although 
