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TECHNIQUE FOR PREPARING LANTERN SLIDES h
A. SOUTHERN Howard College, Birmingham. Alabama
MAKING prints of 35-mm. negatives t o be used as slides is often difficult. The following procedure is simple and has been found satisfactory for making both 2-X %in. or 31/4-X 4-in. slides. The process is that of putting the information (charts, outlimes, diagrams, curves, etc.) on a chalk board, photographing it, and using .the negative itself as the slide. For best results a green chalk board has been used. The area covered on the board is approximately 30 X 40 in. and the picture taken from 41/15 ft. For improved contrast a red filter is used with Plus-X film. Two photoflood lights, situated so as to prevent glare, are used for lighting. Experience shows that a light meter and filter factor are of little use; exposures of 1/100th second a t j 5.6 have given very satisfactory result,^. The board should be cleaned
with a damp cloth after each use, as chalk dust left by an eraser may cause some glare. The 2-X 2-in. sIides are made by mounting the negatives in ready-mounts and for the 31/rX 4-in. slides negatives are mounted between glass plates. A very suitable ready-mount has been obtained at reasonable cost from Craftsman's Guild, Hollywood, California. The 2-X 2-in. slides are produced a t a cost of approximately seven cents each and the ~ ' / c X 4-in. slides a t from ten to twelve cents each. This technique has been used very successfully showing electrical circuits, tables, diagrams, curves, and flow-sheets. Its usefulness will depend on the individuals ability to arrange hi data on the chalk board and his gaining of experience for optimum image size, distance, lighting, and exposure.
JOURNAL O F CHEMICAL EDUCATION
