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.
390 DUNDON, BROWN, AND CAPSTAFF [j. s. M. P. E.
It is believed that under certain conditions such a control test can be very useful.
CONDITIONS CAUSING LOSS OF EXPOSURE
When a silver bromide solvent is present in low concentration in a developer of reasonably strong reduction potential, most of the dissolved silver bromide is reduced as fast as it is dissolved and the silver is redeposited very near to its original location on the developing nuclei already present. When the solvent is too strong or the reducing action too weak, the soluble complex formed with the silver halide escapes into the developer and is slowly reduced, causing a sludge of the reduced silver. In this case, some of the available density for a given exposure is lost,
It is a wdl-known fact that increasing the bromide content of a developer delays the first stages of development. When an image is being rapidly formed by development, it is obvious that so much bromide is released within the film that the influence of ordinary bromide concentrations in the developer is negligible. Therefore, the effect of bromide in the developer is limited largely to the first stages of development.
In the borax developer with a fresh solution containing no bromide, development starts very quickly. When bromide is introduced either directly or by developing film, the appearance of the image is greatly delayed. With 2.0 grams per liter of potassium bromide, 3 or 4 minutes elapse before the shadow detail becomes visible. Meanwhile, the sulfite is exerting its solvent action with the resulting loss of developable image density. This is in agreement with the known fact that bromide in a borax developer causes an effective loss of exposure in film when developed to the customary gamma between 0.6 and 0.8.
To test this idea further, strips of film exposed through a step tablet were bathed for five minutes at 70°F. in a solution of sodium sulfite containing 100 grams per liter, and then developed for differing times in a fresh borax developer at the same temperature. Comparison strips were soaked in water instead of the sulfite solution and developed for the same times. When a gamma of approximately 0.7 was obtained in each case, the film bathed in the sulfite solution showed such a loss of image that it appeared to have an exposure of only about one-third that of the strip bathed in water.
If the solvent action during the induction period before the de