And hail the reign of pleasure.


W.H. PRIDEAUX.

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SPIRIT OF DISCOVERY.

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IMPROVEMENTS IN BLACK WRITING INK.

_By John Bostock, M.D._[2]

When the sulphate of iron and the infusion of galls are added together,
for the purpose of forming ink, we may presume that the metallic salt
or oxide enters into combination with at least four proximate vegetable
principles--gallic acid, tan, mucilage, and extractive matter--all of
which appear to enter into the composition of the soluble parts of the
gall-nut. It has been generally supposed, that two of these, gallic
acid and the tan, are more especially necessary to the constitution of
ink; and hence it is considered, by our best systematic writers, to be
essentially a tanno-gallate of iron. It has been also supposed that
the peroxide of iron alone possesses the property of forming the black
compound which constitutes ink, and that the substance of ink is rather
mechanically suspended in the fluid than dissolved in it.