The various important rôle of gelatin in photographic silver halide emulsions are discussed. In part 1 of this paper, the protective colloid function of gelatin and accelerating property for silver halide grain growth are reviewed.

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A new granularity measuring instrument is descibed in this report. This instrument consits of four distinct parts: the high speed scanning microphotometer, which scans a photographic film at the rate of 100 millimeter per second; the dc amplifier; the frequency analyser, which analyses the wave form to its power spectrum with the twenty narrow band pass. filters; and the meter, which indicates the root mean square value of the current. The scanning aperture, on which the magnified image of grain structure is projected by a microscope optical system, can be replacd with the revolver disc.
Measurement of power spectrum of grain structure is made with this instrument. The normalized autocorrelation function of grain structure can be obtained by Kretzmer's optical autocorrelator, but the level of origin of this function can not be observed. On the other hand, measurement of level of power sectrum which isthe Fourier transform of the autocorrelation function can be made with this instrument descrided in this report. Author also gets the granularity-density functons of various commercial films with this instrument. When this measurement is made, the diameter of the scanning aperture is selected so that its spatial frequenecy character corresponds to the response function of the eye. Then this numerical value of granularity correlates to graininess very well. The correlation coefficient, which is usually spoken of as a measure of the strength of the relationship betwen two variables, is 0.90 in this case.

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The object of this report is to provide a general rule in the selecting of materials for the polarizing film base of the polyiodine polarizer.
As the material for the polarizing film base, polyvinyl alcohol, polyvinyl alcohol borate, polyvinyl formal, and polyvinyl formal borate, are taken up. In the result of consideration and observation for stabilities of their polarizing films, we have found, that the stabilities of polarizing films are consistent with those of film bases.

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Considerations on Callier Q factor using Fourier analysis for optical noise are described.
Q factor, generally, could be given for the film having its amplitude transmittance: A as follows:
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The author assumes that the diveloped silver grain has finite transmittance because of its fine structure, and that grains distribute on film surface followed Poisson distribution. And the formula for the relation on Q and D is obtained. Theoretical results coincide well with experimental ones in low density domain, and factors which affect Q are analysed.
It is clearly explained in this paper that the granularity is not uniquely determined from Q value because Q has not information about the size of grain. But Q is a merit of granularity of one side in its root mean square value.

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Ordinary enlarging papers show high spectral sensitivity in short wavelength region where ordinary enlarging lenses are not corrected, with the result that simple combination of both never give enlarged prints with sufficient sharpness.
Three methods are proposed to compensate the discrepancy between the paper and the lens, i. e.: 1 to extend the chromatic corrections of enlarging lenses down to near ultraviolet. region, in order to match the spectral sensitivity of ordinary enlarging papers: 2 to dye-sensitize the emulsion of enlarging papers up to long wavelength region, where the ordinary enlarging lenses show satisfactory performances when shorter wavelength region be cut off by suitable light filters: or 3 to use ordinary “pure bromide” papers against ordinary enlarging lenses in combination with a light yellow filter.
Similar propositions are given about enlargements upon “electrofax” papers as well as “gaslight”(i. e. chloride) papers.

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The change of silver potential of AgBr-Br- system when the solution of stabilizers was added, the measurement of which is one of some methods for the investigation between stabilizers and silver halide, was in agreement with the photographic properties of them.
This fact with our preceding experimental results one of which the excellent stabilizeres has an upper limit of silver potential, probably means that the some mutual action with silver ion or silver takes part in photographic action of stabilizers.
As the results of consideration the about mechanisms of stabilizing action based on these and E.J. Birr's experimental results, a better way to stabilize the photographic emulsion was found.

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