The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Pizzighellfs Printing-out Platinotype Process
No. 4 Solution, Sodium Ferric Oxalate. Ferric oxalate           ... ... ... ... 308 grs.
Oxalic acid ... ...... ... ... 8 ..
Sodium oxalate ......... 230 to 290 ..
Distilled water ...... ... ... 27 drms.
The exact amount of sodium or ammonium oxalate to use is found by the formation of a brilliant emerald green colour, turning slightly darker as more of the salt is added. The addi-tion of the salt must be stopped at this stage. After shaking slightly, filter the solutions, and preserve from actinic light.
No. 5, Sensitising Liquid.
Solution of chloro-platinite of potash (1 in 6) No. 1...............
n           11 3 •••
Or                                             No. 6.
Solution of chloro-platinite of potash (1 in 6)
No. 4...............
••              ■• i... ... ... ... ...
408
mins.
391
it
374
II
24
mins.
39i
II
374
»>
24 grs.
24
M
3i
M
3
IJ
52
II
480 mins.
Or
No. 7.
Chloro-platinite of potash
Sodium oxalate           ......
Ferric oxalate ...
Oxalic acid ......
Gum arabic ......
Distilled water, to make
The mixtures are well stirred, filtered through muslin, and kept from actinic light. No. 5 gives bluish black, No. 6 brownish black tones. The coating, drying, and storing of the paper are precisely the same as for the original process patented by Willis. Chlorate of potash may be added in the same way, to increase contrast. About 90 minims of sensitising liquid are required for a sheet 10 by 8. The printing may be carried on until the image has appeared in all its parts, and should be no darker when printed than required. When finished, the print is washed in acidified water, as recommended for the old process, and finished in the ordinary way. A second method of printing is to print till the general details are out, but all the half-tones
506