The wool taken out of the liquid and purified by washing
in water and wringing is moistened in a test-tube with pure potassa
lye at 10 per cent. It is carefully heated till the wool is completely
dissolved, and the solution, when cold, is mixed first with half its
volume of pure alcohol, upon which is carefully poured the same volume
of ether, and the whole is shaken. The stratum of ether decanted off is
mixed in a test-tube with a drop of acetic acid. A red color appears if
the slightest trace of magenta is present. The shaking must not be too
violent, lest an emulsion should be formed. If the wine is colored with
archil, on prolonged heating, after the addition of ammonia, it is
decolorized. If it is then let cool and shaken a little, the red color
returns. If the wool is taken out of the hot liquid after the red color
has disappeared, and exposed to the air, it takes a red color. But if
it is quickly taken out of the liquid and at once washed, there remains
merely a trace of color in the wool. If these precautions are observed,
magenta can be distinguished from archil with certainty according to
Koenig's method. As the coloring-matter of archil is not precipitated
by baryta and magnesia, but changed to a purple, the baryta method,
recommended by Pasteur, Balard, and Wurtz, and the magnesia test, are
useless.
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