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.     

The quantitative determination of hypo in photographic prints with silver nitrate

A silver nitrate test is described for the quantitative determination of residual hypo in photographic prints. The hypo is converted in situ to silver sulfide, the transmission density of the sulfide determined, and the hypo content obtained by reference to a standard curve.The method used to establish the standard curve is outlined, the data being verified by quantitative analyses.A simplified procedure is suggested involving the application of a drop of silver nitrate to the back of the print and then matching the spot visually with a set of standards.     

石家庄市秋季可吸入颗粒物垂直分布特征的研究

本文研究了石家庄市秋季可吸入颗粒物质量浓度垂直分布和粒度分布特征。结果表明，环境空气中可吸入颗粒物的众径为0.2μm～1.0μm，比表面积为3536.2～4396.06 m2/kg，PM2.5/PM10高达71.28％～81.14％； 细小颗粒物累积百分含量随高度增加而增加，PM2.5和PM10累积分布随高度增加呈现出对数增加的规律；采样高度1.5m时中位径（D50）>1μm，大于1.5m时 D50均<1μm。不同高度降尘的比表面积为336.55～790.06m2/kg，PM2.5/PM10为19.46～22.47％，D50为9.66～13.78μm，D98在34.93～53.48μm之间。