Gutta percha, its discovery, history, and manifold uses.

Date:
1851
Catalogue details

Licence: Public Domain Mark

Credit: Gutta percha, its discovery, history, and manifold uses. Source: Wellcome Collection.

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    It is a question indeed whether the composition of the two substances is not precisely the same, the small quantity of oxygen detected in Gutta Percha being derived from the air during the process of purification. “Exposed to a temperature of 248®, it melts, and in cooling, remains in a semi-fluid adhe¬ sive state, partially decomposed in fact, and when set on fire it burns very readily with a dense smoke.” At a temperature of about 200® it becomes soft and ductile, though without sticki- t npss, and can be moulded into any shape, which it retains on cooling. In its solid state it is far more rigid than caoutchouc, being only slightly elastic. Its specific gravity is *975, that of water being 1*000. Its tenacity and durability are extraor¬ dinary ; indeed when it does at length wear out it may be renovated and re-manufactured. It is repellant of, and com¬ pletely unaffected by, cold, fresh or salt water, or damp. Of heat and electricity it is a non-conductor. It is alkali and acid proof, being affected only by highly concentrated sulphuric and nitric acid. The most powerful acetic, hydro-fluoric, and muriatic acids and chlorine have no injurious efiect upon it. Its power of resisting frost is extraordinary. And of its sin¬ gular acoustic properties we shall speak more at large, a little further on. II. Having been permitted to inspect the Gutta Percha Com¬ pany’s extensive works, (Wharf Poad, City Poad, London), we are enabled to give a brief sketch of the method in which the raw material is purified and prepared for use, which may be amusing to our readers. The process is in many parts highly ingenious. Eirst of all, the blocks are taken to the cutting machine, a large solid disc of iron revolving vertically at the rate of 200 turns a minute, against the extremity of a sloping iron table. Three sharp knives, projecting somewhat like the iron of a carpenter’s plane, are set upon its surface. The block of Gutta Percha placed upon the table slides down to the disc, where it is caught by the knives and rapidly sliced into shavings, which fail into a receptacle beneath. This
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