Appletons' cyclopaedia of applied mechanics: a dictionary of mechanical engineering and the mechanical arts . strips, or strips of an\ desired shape of section, corresponding with theform of the grooves. Another method of cutting sheets into Strips is by the use of a large numberof parallel blades mounted on a single moving support. The form of calenders used in the manufacture of sheet gutta-percha is represented in Figs, 2232and 2288. The rolls are 6 feet -1 inches long and 22 inches in diameter, each one weighing about7,000 lbs. They are heated by steam. Gutta-percha tubes arc made by forci
Appletons' cyclopaedia of applied mechanics: a dictionary of mechanical engineering and the mechanical arts . strips, or strips of an\ desired shape of section, corresponding with theform of the grooves. Another method of cutting sheets into Strips is by the use of a large numberof parallel blades mounted on a single moving support. The form of calenders used in the manufacture of sheet gutta-percha is represented in Figs, 2232and 2288. The rolls are 6 feet -1 inches long and 22 inches in diameter, each one weighing about7,000 lbs. They are heated by steam. Gutta-percha tubes arc made by forcing the gum over a steel mandrel held as a core in a cylinderof iron. As the material is hot on emerging, the sides of the tube would naturally stick prevent this, the tube as fast as it is formed is led through a vat of water some 50 feet in length. GUTTA-PERCHA. 77 The water, pressing equally on the interior as well as the exterior of the tube, keeps it in shape untilit cools and sets. By this means a single tube of nearly 1,100 feet in length has been made without a break of any kind. An important utilization of gutta-percha is as an insulating material for electrical conducting,wires. A thin coating of the gum may be applied to a wire by passing the latter through a vesselcontaining the gutta-percha in a melted state. This method, however, does not answer for applyingthe gutta-percha envelope to sub-marine or subterranean this purpose the gum is puri-fied with the greatest care, andis placed in a cylinder, where itis kept plastic by heat, and atthe same time is strongly com-pressed by a piston. The wirescomposing the core of the cableare caused to pass through achamber into which the gum alsoenters, and at the same time arerotated, so that they emerge cov-ered with a layer of gutta-percha,which is increased in thickness asdesired by repetitions of the pro-cess. Vulcanization of gutta-perchais effected in the same manner asthat of India-rubber. T
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Keywords: ., bookauthorbenjaminpark18491922, bookcentury1800, bookdecade1880
