The influence of components of ZnO papers on characteristics of image developed by the magnetic brush method under controlled conditions was investigated.
Chatacteristics of image density vs. surface voltage were affected not only by types of Zn Olayers but also by those of supports, according to the following experimental formula.:

where D is image density, V is surface voltage, V_c is critical voltage which represents minimum surface voltage being necessary to obtain appreciable image, and k and n are parameters depending on ZnO layers and supports.
In this formula the value of Vc was affected rather by the support than by the ZnO layer.
From the D vs. log E characteristics, it was found that halftone rendition was influenced strikingly by components of ZnO layers and slightly by those of supports.
Above results suggested that the ZnO layer-support barrier played an impotant role in the image formation.

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The authors have reported in the previous paper about some investigations concerning the transfer of electrostatic latent images. In the preceding experiment, a metal cylinder was used as one of the elecrtodes to perform the image transfer, but it was not suitable for studying the phenomenon quantitatively.
In the present article, additional results are given using another experimental arrangement.
Both the original and the image receiving matter are inserted between two flat electrodes, on which the bias voltage is imposed by a rotating switch.
The voltage pulse width is controlled by varying the effective width of contacting electrode of this switch.
Transfer characteristics are measured under various voltage imposing conditions using electrophotographic paper, plate, and resin coated paper as testing materials.

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We have been interested in the research of the charge transfer mechanism between the dielectric surfaces through the narrow air gap. The electric potential differcnce V₁ induced in the air gap between the two dielectric films put inside of parallel electrodes is indlcated by the fo rmula (4) and found to be a function of the applied volage between electrodes V_a, gap length d₁, thicknesses and dielectric constants of the films, and potential of the surface charge to be transfered.
On the other hand, the spark voltage of the gap is shown by the well known Paschen's curve as the function of the product of d₁ and the pressure p (Fig. 2). smaller the p・d₁, V₁ will be enough to the spark when the charge densithy σ_s is high.
When the polarity of V_a is opposite to σ_s, V₁ is lower and we can reduce the gap and evacuate the system without spark. After then, if V₁ is increased we can determine whether spark potential at small p・d₁ fits the paschen's curve or not.
We have concluded, by this procedure, that the charge transfer ln the narrow gap between dielectric surfaces is done by the syark mechanism.

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As a study on the flexible bases for the electrophotographic transparencies, the effects of several antistatic agents on the electrical properties of cellulose diacetate (CDA) films were examined.
Effective agents for CDA were some cationic surfactants having Cl^- ions (e. g. stearaimidopropyl dimethyl-β-hydroxyethyl ammonium chloride) and an inorganic coating agent namely Colcoat. Anionic and nonionic surfactants were less effective in comparison with the foregoing two.
From the view point of transparency, however, Colcoat or nonionic surfactants were preferable and their combination was found to be practical.
A transparent electrophotography film which was consisted of a polymeric photoconductive layer and a CDA base treated with the two agents gave a good results in the potential decay test and the visual image printing.

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