The ferrotype and how to make it - The Grian Press

110 THE FERROTYPE.
it is pJaced in a bath of a solution of cyanide of
potassium. This bath, for reasons given else-
where, should be kept in an upright bath-dish,
inclosed in a box having a close fitting cover.
The solution should be sufficiently strong to dis-
solve the remaining iodide of silver from the
surface of the plate in from three to five seconds,
when the plate should be taken out and again
subjected to a still more careful washing, in order
that every trace of cyanide of potassium be removed
from the plate. If the picture had, by
over-exposure in the camera or over-development,
been made too light, it may be improved by al-
lowing it to remain for a longer time in the fix-
ing solution ; or it may be dipped in the cyanide
and held over the flame of a lamp or gas-burner,
that the heat may accelerate the action of the
cyanide on the Collodion film, or on the silver of
which the image is composed.
The action of the cyanide is, first, to dissolve
the iodide of silver, after which it will attack the
metallic silver of the image, and by reducing
the deposit of silver in the high lights and else-
where on the plate, it has the effect of darken-
ing the image; or, by thinning the deposit of
silver, what remains is less opaque, thus allow-
ing the black surface of the plate to show through
the shadows and half-tones.
The plate having been perfectly washed, is now
taken to the light and submitted to the inspec-
tion of the lady and her friends, if she is acconi-