We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
40 Transactions of S.M.P.E., Nov. 1924
ly small effect on the latent image if the exposed film emulsion is dry, that is, if it is in equilibrium with an atmosphere of low relative humidity. The experience of numerous explorers in tropical countries who thoroughly dried out their film after exposure and before packing but who did not develop the film for several months afterwards thoroughly establishes this fact.
Effect of a Sudden Change of Temperature on Moist Film
If moist film, that is, film which is in equilibrium with an atmosphere of high relative humidity is suddenly cooled, moisture is apt to condense as droplets on the film emulsion which will cause spots on the developed film. Such spots are termed ''moisture spots. "^ There is ver}^ little danger of the formation of moisture spots due to sudden cooling of the original unopened film cans. The most frequent cause of moisture spots is sudden cooling of the film when in a moist condition in the camera and retorts.
The Care of Motion Picture Film Before Exposure
From the above discussion it is seen that film must be kept dry and as cool as possible before exposure. The film however, must not be too dr}^, otherwise static may be produced in the camera with negative film, and in the printers with positive film. On leaving the factory, motion picture film as contained in the cans is in equilibrium with an atmosphere having a relative humidity of 70 to 75% but the paper wrapping absorbs moisture so that film which is a few months old is relatively drj^ The film cans, however, are not perfectly water-tight and in a very moist atmosphere the packed film would absorb moisture verj^ slowly so that it is preferable to pack film which is liable to be exposed to damp atmospheres in hermetically sealed cans. Film packed in this way can be secured on special order from the manufacturers. Five small cans are contained in an outer can with a soldered inside cover and after exposure the film can be repacked in this outer can and again sealed by soldering the outer cover. If the film is liable to be roughly handled it is preferable to construct carrying cases of heavy sheet metal or fibre impregnated with bakelite and fitted with gasketed covers which can be clamped down with suitable screws or clamps. The containers should not be unduly exposed to the sun, and a layer of white felt around the carrying cases serves to insulate the film from sudden heat changes. Positive film in the laboratory should be stored in the original cans at a temperature as near 65°F. as possible.
Negative films should not be retained for too long a period either in the retorts or in the camera because in a damp atmosphere moisture spots are apt to be produced as explained above. Film should be removed from the original container only as required and in the
2 "Markings on M. P. Film Produced by Drops of Water" by J. I. Crabtree and G. E. Matthews, Trans. Soc. M. P. Eng. Vol. 17, 29.