" Hence this
third enemy is a boiling process, especially a long-continued one if
only with water itself. If we could use coal-tar colours and dye in only
a warm weak acid bath, not boil, we could get better lustre and finish.
We will now turn our attention to the chemical composition of wool and
fur fibres. On chemical analysis still another element is found over and
above those mentioned as the constituents of silk fibre. In silk, you
will recollect, we observed the presence of carbon, hydrogen, oxygen,
and nitrogen. In wool, fur, etc., we must add a fifth constituent,
namely, sulphur. Here is an analysis of pure German wool--Carbon, 49.25
per cent.; hydrogen, 7.57; oxygen, 23.66; nitrogen, 15.86; sulphur,
3.66--total, 100.00. If you heat either wool, fur, or hair to 130 deg. C.,
it begins to decompose, and to give off ammonia; if still further heated
to from 140 deg. to 150 deg. C., vapours containing sulphur are evolved. If some
wool be placed in a dry glass tube, and heated strongly so as to cause
destructive distillation, products containing much carbonate of ammonium
are given off.
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