The manufacturer was thus often
compelled to make many different qualities of the same extract to suit
different customers. For the same reason adulterated articles were
often preferred to the pure ones. There was, perhaps, no branch of
industry in which chemical skill of a high order could be applied with
greater advantage than in dyeing, and nowhere was this fact less
recognized. Some of the processes of dyeing were exceedingly wasteful
and stood in much need of improvement. He (Mr. Siebold) knew a large
works in which a ton of logwood extract was used daily for black
dyeing only, and he might safely assert that of this enormous quantity
only a very small proportion would be fixed on the fiber, while by far
the greater proportion was utterly wasted. Such a waste could only be
prevented by a searching investigation of its causes by trained skill.
Mr. Thomson had further alluded to the color obtained with logwood or
logwood extract and wool mordanted with bichromate of potash, and
seemed to be under the impression that the color thus obtained was not
black, but blue. This was undoubtedly the case in dyeing trials
performed as tests, as these were conducted purposely with a very
small proportion of coloring matter in order to admit of a better
comparison of the resulting depth of shades. But with larger
proportions of logwood the color obtained was a fine bluish-black, and
with the addition of a small proportion of fustic or quercitron bark
to the logwood a jet black was readily produced.
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