66 REPORTS ON THE STATE OF SCIENCE.—1918. 
Silk is modified by boiling in water in a similar manner to wool.° 
The effect of mechanical pressure is also similar with these two fibres. 
Colloid chemical investigations have been made® with the sub- 
stance present in the glands of the silk worm from which the silk is 
spun. The colloid present in these glands coagulates on standing, 
more quickly on heating or freezing or by treatment with dilute 
acids, a tough gelatinous mass being formed. It is interesting to 
note that the coagulation is accelerated by mechanical strain, and the 
suggestion has been made® that the solidification of the silk as spun 
by the silkworm is due to the mechanical strain exerted during 
ejection of the viscous secretion of the silk gland through the 
spinning orifices. This may have some connection with the double 
refraction shown by silk fibres.° 
(L). Silk: 
1 Fischer, Zeit. Physiol Ch. p. 126 (1907). 
? Abderhalden, Zeit. Physiol Chem. 66, 13—18 & 910 and numerous other articles. 
3 Clavel & Lindermeyer, F.P. 451, 897 (1912). 
* Cardazzi, F.P. 457, 326 (1913). 
5 Harrison, Proc. Roy. Soc., A., 94, 460 (1918). @ 
6 Koa, Koll. Zeit. 10, 7—12 (1912). 
7 Farrell, Journ. Soc. Dyers § Cols. 70 (1905). (Action of hydrochloric acid.) 
8 Sansone, Rev. Gen. Mat. Col. 194 (1911). (Action of formic acid.) 
® Hohnel, Journ. Soc. Chem. Ind. 2,172. (Diameter of silk fibres.) 
10 Wardle, Zussur Silk. 
1 Vignon, Recherches sur la soie, Lyon (1892). 
1? Rossinski, Bull, du Labor de la soie, Lyon (1895). 
13 Franceson, Etudes sur la filature de la soie, Lyon (1890). 
14 Collomt, Journ. de Physik. (1785). 
18 Bolley & Schoch, Dingl polyt Journ. 196 (1870). 
16 Cramer, Journ. fur prakt. Chem. 96. 
17 Persoz, Mon. Sci. 1, 597. 
18 Mills & Takamine, Zrans, Chem. Soc., p. 142 (1881). (Absorption of acids.) 
19 Silberman, Die Seide. 
Sizing. 
Very little work of any importance has been done with respect 
to the sizing of textile materials, but a considerable amount of work 
has been done on the materials used in this process. The work 
carried out on glue and gelatine has been fully dealt with by Procter 
in the first report. Practically all the work done on starch has been 
considered by Brown! and by Stocks.? The characteristic blue 
colour produced when iodine is added to starch has been shown to 
be due to colloidal iodine,’ and many other substances have been 
found to give the same reaction. 
The changes undergone by starch during boiling are of great 
importance in relation to sizing and finishing and have received 
considerable attention.*2 The addition of salts has been shown to 
influence these changes.*-® 
The so-called sizing properties of starch are somewhat obscure. 
The process of sizing is carried out for the specific purpose of assist- 
ing in the weaving of fabrics, and the advantages of any particular 
Sizing material can, at present, only be determined by a practical 
test.1 The relationship between the mechanical properties of the 
sized yarns and the physical properties of the sizing materials has 
never been determined. This is mainly due to the difficulty of 
