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.
Screen-Plate Practice 521
when viewed against the light. An excellent developer was obtained by using, instead of the hypo, potassium ferrocyanide, not ferri — , equal to half the weight of the actual reducing agent, thus 4.3 g. in the above formula.
V. Cremier43 stated that a mixture of 10 g. of metol and 5 g. of hydroquinon gave as good results as metoquinon, and that for very brilliant pictures 7 and 8 g. respectively should be used. It should be noted that according to the molecular weights the ratios should be 10 hydroquinon and 22.36 metol. Cremier,44 C. Lelong," E. Mayer,40 G. Winter,47 Mouton,4s H. Bouree,49 J. Carteron50 used metol-hydroquinon in two solutions, adding the ammonia only just before use. A. Watkins51 strongly recommended time development, adjusted for varying temperatures. A. Brizet52 suggested for subjects, that contained much green or grey and showed but little contrast, a developer of :
Metol 6 g.
Hydroquinon 4 g.
Sodium sulfite, anhydrous 40 g.
Potassium bromide 0.24 g.
Hot Water 1000 ccs.
When cool add
Ammonia 13 ccs.
This contains a relatively large proportion of metol and hydroquinon, but it should be borne in mind that metoquinon is 30 per cent more active than a mixture of the two reducing agents. For use 40 parts of above were to be mixed with 80 parts water. This was stated not to fog plates and development could be prolonged to 6 minutes if necessary.
V. Cremier53 pointed out that chloranol, a combination of chlorhydroquinon and metol, introduced by MM. Lumiere, acted more energetically than metoquinon, and it is more soluble in water. The formula recommended was :
Chloranol 1 5 g.
Sodium sulfite, anhydrous 100 g.
Potassium bromide 6 g.
Hot water 1000 ccs.
When cool add
Ammonia 32 ccs.
For use 5 parts of this should he diluted with 100 parts water. Development takes rather longer and the results are more brilliant. J. Carteron54 recommended the following method as giving good control of Autochrome plates. Three dishes were used side by side ; in the first one was either of the following solutions, which destroyed the color-sensitiveness of the emulsion :
A. Potassium bromide 10 g.
Acid sulfite lye 20 ccs.
Water 1000 ccs.