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Cotton Seed Blue

Cotton seed oil is bleached by treatment with either carbonate of soda
or caustic lime. In both cases, a considerable residue is left after
drawing off the bleached oil. This residue is treated with sulphuric
acid, and distilled at a high temperature, when there is left a compact
mass of a deep greenish-blue colour. On further treatment of this mass
with strong sulphuric acid, the green tint disappears, and a very
intense pure blue colour is produced. The blue mass is a mixture of the
coloured substance with some sulphuric acid, sulphate of soda, and fats.
The two former may be removed by washing with water; the latter by
treatment with naptha. Alcohol now dissolves the blue colour, and water
precipitates it from the solution chemically pure.

This blue has not been introduced as a pigment; and of its permanence,
and other attributes, we know nothing.

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