2 parts

Dissolve as said above.

SENSITIZING SOLUTIONS.
FOR BLACK TONES.
Platinite solution, 1:6 5 parts
Solution E 6 parts
Solution C 2 parts

FOR SEPIA TONES.
Platinite solution, 1:6 5 parts
Solution C 4 parts
Solution F 4 parts

Mix just before use. The solutions do not keep. The paper prepared by
either one of these two processes can be exposed as in the _old_ process,
and the image developed bythe hot oxalate solution.

The preparation of wood, canvas, etc., for the platinotype printing need
not to be described; it suggests itself.

CAUSES OF FAILURES.

_The images are veiled._

This defect may result from various causes, viz.:

1st. The stock ferric oxalate solution is impaired by a partial reduction
of the ferric salt into ferrous oxalate. The solution should be
preserved in an orange colored vial, and kept in the closet of the
dark room. It should be tested from time to time for the ferrous
salt with a solution of potassium ferricyanate. If it does not
contain any ferrous oxalate it can be used by adding to it a little
of the iron chlorate solution.
2d. The paper has been exposed to light during the sensitizing or the
subsequent operations. One should bear in mind that the platinum
paper is twice more sensitive than silvered paper.
3d. The sensitized paper has been dried at a temperature above 40 deg.
C. (104. deg. Fahr.)
4th. Over-exposure.

_The proofs are not sharp._

1st. The sensitive paper has absorbed moisture.
2d. It is too old. The paper cannot be kept good for over six weeks,
unless special care be taken.

According to Mr. Bory, the sensitive paper altered by keeping is restored
to its original good quality by simply brushing it over with a solution of
0.05 parts of potassium chloride or the same quantity of potassium
chlorate in 100 parts of distilled water, or a mixture of these two
solutions, or one of iron chlorate.

By treating the insolated paper with these solutions, the image is
destroyed, and the paper can be used again. One operates as for
sensitizing, taking care to desiccate the paper, as it has been directed.

_The proofs are brilliant during the development, but become dull in
drying._

The paper not well sized. It has been dried too slowly.

Remember that it shoul