Scientific American Supplement, No. 711, August 17, 1889Various
History
Scientific American Supplement, No. 711, August 17, 1889
Various
Science -- Periodicals
The presence in dyewood extracts of coloring matters in various stages
of development has hitherto militated against their use in place of
the raw materials by many dyers and printers who are still employing
inherited and antiquated processes in which the whole of the coloring
matter is not rendered available. It is often asserted by these that
even the best of extracts fail to give anything like the results
attained by the use of well-prepared woods, and that, indeed, their
application proves a complete failure. Such failure, however, is
simply due to the want of chemical knowledge on the part of the dyers,
for there is no real difficulty in making any good and pure extract
serve all the purposes for which the woods were used. It is to be
hoped that in this branch of industry, as well as in many others, the
employment of chemists will become more general than at present, and
not be restricted, as is often the case, to young men without
experience and without the trained intellect so essential to success
in chemical investigations. High class chemical skill is of course
available to the manufacturer, but the man of science who brings
matured knowledge and valuable brain work into the business required
social as well as pecuniary recognition, and the sooner and more
fuller this fact is appreciated the better it will be for the
maintenance and progress of our industries.
With regard to the astringent extracts, such as sumac, myrabolam,
divi, valonia, quebracho, oak, etc., it is the aim of the
manufacturer, whenever such extracts are intended for the purposes of
dyeing and printing, to obtain the tannin in a form in which it is
best calculated to fix itself upon the fiber. The case is somewhat
different when the same extracts are required for tanning. For this
purpose it is necessary that the extract shall have considerable
permeating power, and that the tannin contained in it shall readily
yield leather of the desired texture, color, and permanency. Extracts
specially suited for this purpose are by no means always the most
suitable for the dyer, and _vice versa_.
A brief description of the processes by which the astringent extracts
may be tested with particular reference to their fitness for definite
purposes concluded the paper.
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