The reaction of typical reactive couplers carrying the dichlorotriazinyl group with gelatins was discussed. The replacement of chlorine atom was enhanced by the presence of gelatin, and the conversion ratio went up to 54 to 78%. The hydrolysis of coupler was depressed by the presence of gelatin. The reaction of coupler with gelatin proceeded predominantly, and 83 to 92% of observed chloride ion was generated by the reaction of coupler with gelatin. Among the reaction of coupler with polymers (polyvinylalcohol, polyethyleneimine and gelatin), gelatin exhibited the highest reactivity. The introduction of the basic group into polymer raises the reactivity of polymer.

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Conversion of AgBr or AgBrI emulsion grains to AgI is examined by an electron microscope. The direct observation of emulsion layers containing converted silver halide grains shows us what happened on and around the original silver halide grains during the conversion.
Fine (several hundred angstroms) AgI grains are formed around the original grains as a cloud. The breadth of the cloud reaches even severalfold of original grain size.
On the conversion of AgBr cubes or octahedra in KI solution containing polyethylene oxide (PEO), the streams of fine AgI grains pour out to the emulsion layer, presumedly from the corners of original grains. Increasing the amount of PEO, the regions where fine AgI grains are formed do not restlicted only around the original grains, they are distributed over all regions of emulsion layer. PEO accelarates the rate of recrystallization of fine AgI grains formed on the surface of AgBr grains and makes them coalescence. Accelerating effect of PEO is more pronounced in AgBrI than in AgBr grains.

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Emulsion layers containing AgBr or AgCr grains are treated with KCl or KBr solutions and growth hillocks of AgCl produced on AgBr and that of AgBr on AgCl are observed by electron microscope. On conversion of AgBr cubic grains to AgCl, AgCl is formed preferentially at corners of AgBr grains. Fog density increases as time of conversion to AgCl is prolonged, and fog centers are formed along edges of small AgCl grains formed on AgBr grains.
On conversion of AgBr tabular grains to AgCl, AgCl is formed on sides or flat faces of AgBr grains.
AgBr grains formed on AgCl substrate grains by conversion of AgCl to AgBr are not necessarily connected tightly with AgCl, and some of them are formed at visinity of AgCl.

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Reciprocity law characteristics was studied for the range from visible light to 15 McVp X-rays.
It was found that the reciprocity law does not hold for high energy range and the shape of the reciprocity curves is in the opposite direction to that in the case of visible light. For one of the causes to the reciprocity law failure, the effect of radiation damage on the silver halide crystal is suggested.

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The effect of the composition of silver halides upon the Capri Blue effect by phenosafranine has been examined. The Capri Blue effect was observed in mixed silver halide grains (AgBrI and AgBrC1), but was not observed in pure ones (AgCI, AgBr, and AgI). The ratio of internal/surface speed was much larger in the mixed grains than in the pure ones. Namely, in accord with the previous report, the Capri Blue effect was observed in the grains whose ratio of internal/surface speed was large.

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In order to study the flocculation mechanism of positive silver iodide sols by polyvinyl pyrrolidone (PVP), the stability and the electrophoretic mobility of the sols in the presence of PVP were measured, as well as the amount of adsorbed PVP on the silver iodide powder suspended in the same medium as the sol particles were suspended in. As PVP materials, PVP K-90, K-60, K-30 and K-15 were used. A pronounced lowering of the sol stability by the flocculating action of PVP is observed over a certain range of PVP concentration. This range is wider than that for negatively charged gelatin and narrower than that for polyvinyl alcohol. The sol stability is not appreciably influenced by the molecular weight of PVP. The sol particles covered with PVP exhibits a negative ζ-potential. The PVPs used behave like a negatively charged polyelectrolyte in regard to the flocculation of positive silver iodide sols.

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Laser oscillation was observed from dye solutions prepared by various combinations of four cyanine dyes and five solvents using a Q-switch ruby laser as pumping light. The spectral range of laser oscillation thus obtained was near infrared, ranging from 707 nm to 812 nm. The spectrum changed with the concentration of solution and shifted toward longer wavelength with increasing concentration. The largest shift was about 50 nm/mol in some combinations of dye and solvent while the smallest shift was about 20 nm/mol. Regardless of the solvent used, all the dyes showed a spectral width of 50 nm-80 nm near a medium concentration optimal for laser ocillation. The resonator used was 200 mm in length and equipped with two reflecting mirrors, one with 99% reflectivity and the other with 30% reflectivity. The dye cell was a 10×10×40 mm quartz cuvette and pumped from the direction normal to the resonator. The conversion efficiency in laser osicllation was 21% at maxium and the peak power reached 2.1 MW at maximum. The half width of laser pulse was about 20 ns and a time delay of about 20 ns was observed between laser pulse and puming pulse.

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This work intends to verify the action of the Iodide ion in annealed single crystals of Silver Bromide. Lifetime of photoliberated electrons in AgBr and AgBrI crystals were directly measured by means of photoconductivity techniques (at 80°K). The values obtained indicate that electrons are necessarily capturated by traps situated at 0.75-0.77 eV below the bottom of the conduction band mainly proceeding from structural ionized defects created by the I^-. This makes it necessary to reconsider some points of Michell's theory of latent image formation.

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