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Cyanotype |
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A.
Ammonio-citrate of iron ... ... ... 90 parts.
Water ......... .... ... 300 ,,
B.
Potassium ferridcyanide ... ... ... 80 parts.
Liquor Ammonia ... ... ... ... 7 ,,
Water ............... 300 ..
Sat. Sol.oxalic acid... ... ... ... 60 .. |
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This is more sensitive. Ehrmann and Fries suggested the
addition of bichromate of potash, the former stating that this
addition kept the papers unchanged for from three to five months. Ehrmann's formula is |
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A.
Ammonio-citrate of iron ... ... ... 60 parts.
Water ............... 256 ..
B.
Potassium ferridcyanide ... ... ... 40 parts.
Water ............... 256 ,, |
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Mix in equaltparts, and to every 960 parts of the mixture add 1 part of bichromate of potash. Watt suggested the addition of boric acid for the same purpose. |
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A.
Ammonio-citrate of iron ... ... ... 96 parts.
Boric acid ... ... ... ... ... 1 part.
Water ... 0............ 190 parts.
B.
Potassium ferridcyanide ... ... ... 96 parts.
Water ............... 196 .. |
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Mix in equal parts. Rockwood suggested the addition of gum Arabic, or dextrin, as a preventive of the solution sinking into the paper.
A. Potassium ferridcyanide ... ... ... 1 part.
Water ............... 10 parts.
167 |
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