Ferric oxalate solution 100 parts
Neutral ammonium oxalate 18 to 20 parts

B. SODIO-FERRIC OXALATE SOLUTION
Ferric oxalate solution 100 parts
Neutral sodium oxalate 15 to 18 parts

To prepare these two solutions the ammonium or sodium oxalate is dissolved
by small quantities at a time, and when the emerald color due to the
formation of the double oxalate commences to darken, the saturation being
then complete, no more of either salt should be added. The solution is
now well shaken with 3 parts of glycerine, allowed to settle and filtered.

Any one of the double oxalates can be used. The ammonium tends to produce
softer pictures and bluish tones. To obtain more contrasts a little
potassium chlorate may be added.

C. IRON CHLORATE SOLUTION
Solution B 100 parts
Potassium chlorate 0.4 part

D. MERCURIC SOLUTION.
Mercuric chloride 20 parts
solution at 5:100
Sodium oxalate solution 40 parts
at 3:100
Glycerine 2 parts

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

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

Intermediate tones are obtained by diminishing the dose of C and replacing
it by an equal volume of B. For this process the paper should be sized
with

Arrowroot 2 parts
Sodium oxalate at 3:100 100 parts

To dispense with this preliminary sizing Captain Pizzighelli adds gum
arabic to the platinite solution, whereby the sizing and sensitizing are
done in one operation.

The gum arabic solutions are prepared as follows:

E. Gum arabic in 40 parts
powder
Sodium ferric 40 parts
oxalate solution,
B
Sodium oxalate 100 parts
solution at 3:100
Glycerine 3 parts

Place the glycerine and the gum arabic in a mortar, then, stirring with
the pestle, dissolve by adding, little by little, the mixture, heated to
40--45 deg. C. (104--113 deg. Fahr.), of the solution of sodium ferric
oxalate and sodium oxalate. Let stand for about two hours and grind again
to dissolve entirely the gum arabic. Filter through muslin.

F. Mercuric chloride 20 parts
solution, 5:100
Sodium oxalate solution, 40 parts
3:100
Gum arabic in powder 24 parts
Glycerine