vestigations. 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.

With regard to the question as to whether experimental dyeing with
bichromate of potash should be employed as a test even in works where
all the dyeing was done with other mordants, he was decidedly of
opinion that it should always be resorted to as one of the tests,
inasmuch as it was the only simple and expeditious method giving a
fair idea of the actual wood strength and money value of the extract.
The test should, in such cases, be supplemented by dyeing trials with
the mordants used at the works, and, if necessary, also by a chemical
analysis. Printing trials were not necessarily bad tests, since
oxidizing was usually added in these where it was necessary, and any
undeveloped coloring matter would thus be oxidized during the steaming
process: but, as he had stated before, it was essentially necessary in
such cases to have a fair idea of the amount of actual coloring matter
in the extract and to adjust the proportion of mordant accordingly.
Such trials should therefore be preceded by carefully conducted dyeing
trials with bichromate of potash. Mr. Thomson had raised the question
whether it would not be well for the manufacturer to prepare these
extracts in such a manner that they would contain all th