Other alums exist, such as the double sulphate
of alumina and sodium, and sodium or aluminum and ammonium; but hitherto
their uses have been confined to the experimental portion of the
community rather than the practical.--_Photo. News_.
* * * * *
CLOTH STRETCHING MACHINE.
As is well known, in the process of bleaching and dyeing, cotton cloths
become considerably contracted in the width, in consequence of carrying
on the operations when the cloth is in the form of a rope. The effect is
that, together with the tension, although slight, and the drying, the
weft partly shrinks and partly curls up, the latter, however, being
scarcely observable to the naked eye. It may almost be said that as
regards the width the shrinkage is due to a number of minute crumples
because the cloth is easily streatched again by the fingers almost to
its gray width. The main use of a stretching machine, therefore, is not
so much to make the cloth more than it is as to bring it again to its
normal or woven width after operations that tend to shrinkage have been
performed upon it.
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