The Sun.
London, England, 1851-04-10 00:00:00

PREPARATION AND BLEACHING

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OF FLAX.
Wo have had occasion so often to notice the usefu
tendency of the scientific discourses at the Royal Poly.
technic Institution that further comment would be un.
necessary, but our attention has been specially directed
to Mr. John H. Pepper's lecture on " the Preparation
and Bleaching of Flax," which afforded much satisfac-
tion. The lecturer commenced his observations by
speaking in the highest terms of the kind philanthropy
of Mr. Beale Brown, who had at his own charge lectured
at the Polytechnic, for the sole purpose of awakening in
the minds of agriculturists a sense of the great value of
the eultoro and growth of flax; that about nine mil-
lions were paid annually to foreign countries for this
article which we might very well raise ourselves. After
a brief description of the preparation of the plant, a
section of which might be described by three concentric
circles, viz,, the epidermis or outer bark, the liber or
inner bark (wherein the fibre resides) called the heart, and
centre circle, composed of woody matter, termed the
boon; after explaining the:retting, rotting, or rusting,:the
breaking and scutching, and the heckling, the lecturer
alluded to the various new chemical processes which had
been devised to get rid of the troublesome operation of
retting, and stated that a handsome fortune would re-
ward the discoverer of a new, complete, and expeditious
plan of preparing the flax yarn; but care was required
in all chemical processes to prevent the weakening or
partial destruction of the fibre. All flax contained, how-
ever, colouring matter, which it was necessary:to:get rid
of in the best kind of goods, white and fair linen of
course being an absolute requisite of civilised life. Bleach-
ing agents might be considered under three heads-Ist,
Absorptive agents, such as charcoal; 2d, Deoxydising
or hydrogen giving agents, as in the preparation of white
indigo by protoxido of iron; 3d, Oxydising agents, which
were very numerous, and of these chlorine was the most
valuable. After alluding to the first and second, which
were not used for bleaching fabrics, the lecturer pro-
ceeded, by a number of experiments, to show the
agency of chlorine. This important element was
discovered by Scheele in 1774; but it was
the celebrated French chemist Berthollet who
who first thought of applying it to bleach cloth, and in
1787 Mr. Milne, of Aberdeen, and the celebrated Watt
introduced it into the bleach fields of England. In 1798
Mr. Tennant discovered that th© alkaline earths, such
es lime or barytes, might be united with chlorine, arid
serve the same purpose. From that period chloride of
lime has been manufactured on an enormous scale, and
is ustd fur bleaching in large quantities. Some flax
was now rapidly deprived of colours by chloride of
lime, the lecturer explaining that the lecture- tuble
process would be too quick for useful purposee, and
rotted or destroyed the flax. Six weeks were usually
required, and some idea could be formed of the value of
chlorine when it had been stated that as much cloth
could be bleached in six weeks on a 100 square yards as
was formerly conducted on 100 acres in six months.
22 distinct operations were counted by the lecturer as
required for bleaching cotton, which only lost one-
twentieth of its weight, whilst from thirty to forty were
necessary for linen goods, and they lost one-third during
the processes. Mr. Pepper observed, that the philo-
sophy of bleaching depended on the evolution of oxygen,
and a conclusive experiment wns finally shown, in which