We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
512 History of Three-Color Photography
of such adjustment being that pinachrom sensitizes for yellow; pinaverdol for green and pinacyanol for red. E. Vallot made a nickel-plated tank, in which several plates might be immersed in the bath. The principal feature being that a stopcock was arranged to draw off the solution in 2 minutes, in which case capillary action practically left the plates dry when withdrawn. The difference in time of immersion of the top and bottom of the plate seemed to have no harmful effects.10
Ultra-Sensitizing Screen-Plates. — F. Monpillard deposited in 1913 a sealed paper describing this process with the Societe Franchise de Photographic, but it was not opened till eight years later.11 Treatment of the plates by this process would seem to increase the sensitiveness about thirty times ; but unfortunately the plates have but poor keeping power, 36 hours being about the limit. Three stock solutions of dyes are required :
A. Pinaverdol, 0.1 per cent in 90° alcohol.
B. Pinachrom, 0.005 per cent in 90° alcohol.
C. Pinacyanol, 0.005 per cent in 90° alcohol. From these a concentrated solution D was made :
A solution 100 ccs.
B solution 100 ccs.
C solution 47 ccs.
And a concentrated sensitizer E :
D solution 400 ccs.
Alcohol, 90° 600 ccs.
A further solution F, of silver chloride in ammonia is required:
Silver chloride 0.2 g.
Ammonia, 22° 8 ccs.
Water 92 ccs.
The actual sensitizing solution was compounded of :
E solution 100 ccs.
F solution 100 ccs.
Alcohol, 22.5° 800 ccs.
The plates should be bathed at a low temperature for 5 minutes, rapidly washed and dried by heat. It is important that the plates be developed as soon after exposure as possible. The silver chloride and solution F must be prepared in non-actinic light.
A. Ninck12 utilizing the above method with Lumiere's pantochrome as the sensitizing dye, recommended a 1 : 2,500 alcoholic solution of the dye and a 2 per cent solution of silver chloride in ammonia. This last was prepared by dissolving 3.2 g. silver nitrate in 64 ccs. distilled water, adding 1.3 ccs. pure hydrochloric acid, then adding ammonia solution 135 ccs. The actual sensitizing bath was :
Dye solution 20 ccs.
Silver chloride solution 6.6 ccs.
Water 1000 ccs.
Time of bathing 5 minutes at 10 to 12° C, though increase of the temperature merely shortened the time of bathing. The plates were rapidly