GUTTAPERCHA (Pr. and Ger., Guttapercha) A natural product having many similarities to indiarubber, but capable of being made plastic and malleable by heat, and retaining, when cold, any shape given it while hot. Whereas gutta percha is plastic, indiarubber is elastic ; and whereas indiarubber easily combines with sul phur, guttapercha will neither combine nor intimately mix with that substance. Gutta percha is the coagulated juice of the Isonandra cross movement. The exposures were given by a rotating disc with twelve openings, moving at a different speed to the plate. A fixed partition, having a single aperture, was placed between the plate and the shutter disc, so that 4 different portion of the plate, then at rest, was exposed each time an opening in the shutter passed the fixed aperture. The operation was repeated four times to obtain a satisfactory record. On this model Marey founded later his photographic gun B. A long-focus lens was placed at the end of the barrel, thus rendering it feasible to photograph small objects from a distance, and the tube was arranged to telescope for focusing. The clockwork mechanism is illustrated at C, the back cover being removed. On pressing the trigger n, a circular shutter with one aperture commenced revolving. Be hind this rotated a disc r with twelve openings (only half is here shown), the sensitive plate revolving at the back of the disc by friction. The perforated disc and plate were moved intermittently by a pawl G, on an arm worked by an eccentric, and each time one of the openings in the disc p came to rest in line with the lens the aperture in the shutter passed in front of it, making an exposure. During its movement
gutta, which grows in the tropics, particularly in the Malay district. Its principal uses in photo graphy are as a material for dishes and bottles to contain hydrofluoric acid, and as a mountant. For the latter purpose, a piece of very thin sheet guttapercha, the size of the print, is placed on the mount, next the print is laid over it, and then comes a sheet of blotting-paper, over which a hot iron is passed slowly and firmly. The heat softens the guttapercha, which then adheres to both mount and print. An objection to the method is the liability of the guttapercha to perish.
A cement, made by dissolving 2 parts of shredded guttapercha and a parts of powdered Syrian asphalt in a mixture of io parts of oil of turpentine and 5 parts of carbon bisulphide, makes an excellent cement for leather and other materials.
Guttapercha has been used for coating paper in order to transfer collodion films. It has also been used for stripping negatives, instead of using rubber solution. By the addition of gutta percha to collodion the latter is rendered not only tougher, but more sensitive.