PHOTOGRAPhiC literature contains an abundance of information relative to certain scientific phases of flashlight photography. The major portion of this literature deals with the chemical content of the flash materials with descriptions of apparatus for the discharge of such materials. It is the purpose of this paper to present information of another nature, that of the photographic intensity of flash materials.
A problem of this type necessarily involves considerable experimental data, and due to the great variety of flash materials available two were selected whose use is widespread, while a third was included as a possible means of corroborating the evidence of one of the others. In a photographic problem the choice of photographic materials is highly important, especially so when the material used is the medium by which intensity values are to be determined.
The flash materials used in this work were Eastman Flash Powder No. 3, magnesium powder, and magnesium ribbon, while the photographic materials consisted of Seed 23, Standard orthonon, and Wratten and Wainwright panchromatic plates. Each flash material had its intensity value determined on each of the three photographic materials.
Eastman Flash Powder contains magnesium and other metallic powders and substances which act as accelerators of its combustion. This powder is highly combustible and instantaneous in its action. An apparatus was constructed for the electrical discharge of the powder, each discharge firing one gram. This was accomplished by using nichrome wire between the terminals from the source of electrical supply, the wire being filed thin where it passed into the discharge container.