f any single test, they
should be supplemented by the subsidiary tests already alluded to, and
also by a chemical examination, in order to obtain a knowledge, not
merely of the wood strength, but also of the general nature of the
extract. An adulteration with molasses or glucose can be best
determined by fermentation in comparison with a pure sample. Mineral
adulterants may, of course, be detected by an estimation and analysis
of the ash, after making due allowances for variations due to
differences in different kinds of the same dyewoods. The estimation of
the individual coloring matters in these extracts by means of a
chemical analysis is under all circumstances a task requiring much
experience, especially as the coloring principles are associated in
different qualities of each class of dyewood with different
proportions of other constituents which often give much trouble to the
unpracticed experimenter. Extracts made from logwood roots are now
largely manufactured and often substituted or mixed with the extracts
of real logwood, and have in some instances been palmed of as logwood
extracts of high quality. The correct determination of such
admixtures, like the fixing of anything like the exact commercial
value of dyewood extracts, requires nothing less than a complete
chemical investigation coupled with numerous dyeing trials in
comparison with standard preparations, and should be left to an
expert.

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 in