58 REPORTS ON THE STATE OF SCTIENCE.—1918. 
Mercerised Cotton. 
It was first observed by Mercer *~* that cotton fibres shrink when 
they are treated with concentrated solutions of caustic soda. This 
shrinkage has been shown’ to be caused by the action of internal 
stresses present in natural cotton fibres. If prevented from shrink- 
ing while under treatment with the alkali, the fibres acquire an 
increased lustre. °-§ Lange * considered this lustre to be due to the 
smoothness of the surface of the mercerised fibres as compared with 
untreated cotton. Hiibner & Pope ® suggested that the formation of 
regular spiral grooves in the fibre during mercerisation was the cause 
of the lustre. This theory has been shown’ to be untenable, Lange’s 
theory being substantially correct. The shape of the cross-section of 
the mercerised fibres has been shown to have an important bearing 
on the lustre. ” 
The amount of caustic soda absorbed by cotton during merceri- 
sation has been investigated by several workers.4-! *8 Vieweg!# 
observed change points in the curve of absorption but Miller “ found 
the curve to be continuous. Clayton Beadle & Stevens made some 
interesting observations on the absorption of caustic soda by regener- | 
ated cellulose which have an important bearing on this subject. 
Mercerised cotton has properties which differ from those of 
ordinary cotton in the following manner :— 
It grinds more pasty in the hollander, 1°" dissolves quicker in 
solvents, gives a greater yield of benzoyl derivative, 18 gives nitrates 
more soluble in solvents 1 but giving less viscous solutions 2’ and 
gives a blue colour with iodine with a less concentrated solution of 
sulphuric acid than ordinary cotton.’ In the last case, the applica- 
tion of tension during mercerisation has been shown to modify the 
reaction. 
All these properties are in agreement with the view that 
mercerisation produces distension of the fibre—colloid. 
Mercerised cotton appears to revert towards its original condition 
on drying,”! °° or on treatment with alcohol.2? Green” considers 
this reversion to be due to anhydride formation, but the author 
thinks it is an ordinary case of gel-dehydration, since the same 
effect is produced by pressure without the application of heat or 
chemical re-agents.?> A similar change is produced by pressure on 
wet unmercerised cotton,” the effect being much greater when 
heat also is applied.?6 27 
The internal structure of cotton fibres,?*-** and the internal 
stresses present in them (A 12) are considerably modified by 
mercerisation : these changes persist when the fibres are dried. 
The dyeing properties of cotton,*4 ** and its re-activity towards 
certain re-agents, are modified in a similar manner to that produced 
by caustic alkalies, when’ treated with solutions of sulphuric, 
hydrochloric® and nitric acids*” and zine chloride.* 4 
(D) Mercerised Cotton. 
1 Cross & Bevan, Researches, I. p. 26. 
2? Gardener, Wercerisation. : 
3 Mercer, Life and Labours of John Mercer, Parnell (Longmans, Green), 1884, 
4 Mercer, H. P. 13296 (1850). 
5 Lowe, HE. P. 20314 (1889). 
