produced from blani: 35-mm leader by first etching it in saturated potassium hydr-xide solution, then rinsing it in three water baths, in the lest of which itwas dip coated with water soluble nlastic mix, A te suction apparatus mounted beyomi the vclastic dip bath cleaned the cous plastic from the sprocket holes. Three 500-ft reels of film can be processed at one time at the rate of about 3/4-ft/min, $0 11 Sun ye Un To properly sensitize sea water droplet impressions collected on sensitive film, they must be exposed to high intensity solar radiae 2» .« This was accomplished with a hood-like errangement containing six um lamps which fitted onto the film coaster over the empty wash tanks; the drive system pulled the film beneath the lighted lamps. The sun Yemp hood was connected to the ventilating system through filters and the movement of air both cooled the film and entrapped any loosened radioactive particles. 2-32.12 Radioactivity Monitor It was necessary to define the areas of activity on droplet expozed film so that radioautographs could be made. For this purpose, an end window Geiger tube was susnended above the film and connected to @ count rate meter, thence to an Esterline Angus recorder. Activity recording was combined with the sun lamn exvosure. By calibrating the coater drive speed with the recorder speed, the exact location of any active areas could be determined. Z2e313 Vapor Phase Reducing Unit To properly develop sea water and distilled water spots on the sensitive film, vapors of certain chemicals in controlled amounts and wader controlled conditions must he brought into contact with the film surface, The developing apparatus consisted of three temperature controlled units; one for the saturation of air with phenylhydrazine vapors, one to saturate air with water vepor, and the central unit where the two vapors were mixed with ammonia gas. The central reducing chamber was an oil jacketed tank through which the film was drawn into contact with the reducing chemical vapors. All of the saturation units, temperature control systems, and heat exchanger coils were comvletely immersed in o11 baths contained in stainless stec] tanks surrounded with fiberglass insulation. The sunlamp treated film was led from the reducing chamber through a thermal drying chamber to a wind-up reel. 2.3.14 Microscope Traversing Mechanism This unit was built to allow a rapid survey of hundreds of feet of processed film. A precision stage was devised which allowed the film to be tracked under the lens system without scratching the silvered surfaces. A counting device mounted on the stage allowed an accurate computation of the film footage passing across the stage. 25