The development of the solarized latent image

An investigation has been made of the development of the solarized latent image with p-amino-phenol, pyrogallol and hydroquinone developer without potassium bromide, and with a series of hydroquinone developers containing potassium bromide from 0.002N to 0.269N solution. These developers represent a series with different reduction potentials. The investigation was restricted to a pure silver bromide emulsion.It was shown by the application of the Bravais-Pearson method of determination of the correlation coefficient that A. H. Nietz' straight line proportionality between density and the logarithm of the potassium bromide concentration holds in general for normal exposures, but that in extreme cases of exposure and development, deviations from the straight line proportionality are detectable. This proportionality holds only in a limited way for the solarization region. At the threshold of the first reversal of the solarization there is no correlation at all.The criterion that a family of curves has, or has not, a tie-point was investigated by the determination of the correlation coefficient between density and gamma. It was shown that the tie-point of the solarization curves moves toward the origin of the distance/log E axes with increasing content of potassium bromide in the developer.     

The action of hydrogen peroxide on photographic gelatino-silver halide emulsions

1. The sensitometric characteristics of photographic plates exposed to hydrogen peroxide and developed are strikingly similar, both for time of exposures, time of development, and intensity i.e., concentration). Characteristic curves similar to H. and D. curves were obtained, including a period of “reversal.”2. A tentative theory of the action of hydrogen peroxide is suggested. It is supposed that the decomposition of peroxide is chemi-luminiscent, short wave-length radiation being afforded at the surface of the silver halide grain, and particularly at check the hypothesis that these nuclei consist of colloid silver.The authors desire to express their thanks to Mr. R. F. Quirk and Mr. E. Huberth for painstaking assistance in the experi- mental work, and to Miss Anber J. Benedict for making the pH measurements.