far as
introducing any essential variation of the mercerising treatment.

The third section of the work describes in detail the various mechanical
devices which have been patented for carrying out the treatment on yarn
and cloth.

The fourth section deals with the fundamental facts underlying the
process and effects summed up in the term 'mercerisation.' These are as
follows:--

(a) Although all forms of fibrous celluloses are similarly affected by
strong alkaline solutions, it is only the Egyptian and other
long-stapled cottons--i.e. the goods made from them--which under the
treatment acquire the special high lustre which ranks as 'silky.' Goods
made from American cottons acquire a certain 'finish' and lustre, but
the effects are not such as to have an industrial value--i.e. a value
proportional to the cost of treatment.

(b) The lustre is determined by exposing the goods to strong tension,
either when under the action of the alkali, or subsequently, but only
when the cellulose is in the special condition of hydration which is the
main chemical effect of the mercerising treatment.

(c) The degree of tension required is approximately that which opposes
the shrinkage in dimensions, otherwise determined by the action of the
alkali. The following table exhibits the variations of shrinkage of
Egyptian when mercerised without tension, under varying conditions as
regards the essential factors of the treatment--viz. (1) concentration
of the alkaline lye, (2) temperature, and (3) duration of action (the
latter being of subordinate moment):--

_______________________________________________________________________
| | | | | |
| Concentration | | | | |
| of lye (NaOH) | 5 deg.B. | 10 deg.B. | 15 deg.B | 25 deg.B |
| | | | | | | | | | | |
| Duration of | | | | | | | | | | |
| action in | 1 | 10 | 30 | 1 | 10 | 30 | 1 | 10 | 30 | |
| minutes | | | | | | | | | | |
| | | | | | | | | | | |
| Temperatures | Percentage shrinkages (Egyptian yarns) as under:-- |
| as under:-- | | | | | | | | | | |
| 2 deg. | 0 | 0 | 0 | 1 | 1 | 1 | 12.2 | 15.2 | 15.