Gutta-percha-covered copper wires were formerly largely used for the purpose of underground lines, the copper conductor weighing 40 lb per statute mile, and the gutta-percha covering 50 lb (90 lb total).
In 1859 he began, in concert with Sir William Thomson (afterwards Lord Kelvin), to work on problems respecting the making and use of cables, and the importance of his researches on the resistance of gutta-percha was at once recognized.
Connexion is made into the office (or to the underground system, as is often the case) from the aerial wire by means of a copper conductor, insulated with gutta-percha, which passes through a " leading in " cup, whereby leakage is prevented between the wire and the pole.
copper wires insulated with carefully dried paper of a special quality, has practically entirely superseded the use of wires insulated with gutta-percha.
Owing to the high price of gutta-percha the tendency, of recent years, has been to approximate more closely to the theoretical dimensions, x xvl.
mixture of gutta-percha, rosin and Stockholm tar).
The cost of the cable before laying depends on the dimensions of its core, the gutta-percha, which still forms the only trustworthy insulator known, constituting the principal item of the expense; for an Atlantic cable of the most approved construction the cost may be taken at f250 to £300 per nautical mile.
As the wire is pulled through, a coating of gutta-percha, the thickness of which is regulated by the die D, is pressed out of the cylinder by applying the requisite pressure
It is a well-ascertained fact that the insulator, gutta-percha, is, when kept under water, practically imperishable, so that it is only the original strength of the sheathing wires and the deterioration allowable in them that have to be considered.
Beckerite, a rare amber in earthy-brown nodules, almost opaque, said to be related in properties to gutta-percha.
The external trade of the Russian empire (bullion and the external trade of Finland not included) since the year 1886 is shown in the following table: The exports rank in the following order :- cereals (wheat, barley, rye, oats, maize, buckwheat) and flour, 49.2%; timber and wooden wares, 7.2; petroleum, 5.8; eggs, 5.4; flax, 5; butter, 3; sugar, 2-4; cottons and oilcake, 2 each; oleaginous seeds, &c., 1.5; with hemp, spirits, poultry, game, bristles, hair, furs, leather, manganese ore, wool, caviare, live-stock, gutta-percha, vegetables and fruit, and tobacco.
It thus possesses the same composition as the hydrocarbon of gutta-percha and as that of oil of turpentine and other terpenes which are the chief components of essential oils.
In this respect it differs from gutta-percha, which, like caoutchouc, is derived from the latices of certain plants.
Similar products are also formed by heating gutta-percha which closely resembles caoutchouc in its chemical structure.
The hydrocarbon of gutta-percha yields similar results and is therefore closely related to caoutchouc.
Species of Palaquium, the genus from which, in the Indian Archipelago, the best gutta-percha is obtained, occur on the hills, and from their cultivation there might in time be obtained a large revenue independently of European labour.
Pepper, nutmegs and cloves were long the objects of the most important branch of Dutch commerce; and gutta-percha, camphor, dammar, benzoin and other forest products have a place among the exports.
Only one compound of hydrogen and fluorine is known, namely hydrofluoric acid, HF or H 2 F 2, which was first obtained by C. Scheele in 1771 by decomposing fluor-spar with concentrated sulphuric acid, a method still used for the commercial preparation of the aqueous solution of the acid, the mixture being distilled from leaden retorts and the acid stored in leaden or gutta-percha bottles.
Forest products - gums and resins of various sorts, such as gutta-percha - are valuable articles of export.
There are gutta-percha, india-rubber and other trees and plants yielding gums, the banana, mango, and many other trees and plants yielding fruits; and various trees and plants yielding nuts, spices, oils and medicines.
Gutta-percha (getah percha in the vernacular), camphor, cinnamon, cloves, nutmegs, gambir and betel, or areca-nuts, are all produced in the island; most of the tropical fruits flourish, including the much-admired but, to the uninitiated, most evil-smelling durian, a large fruit with an exceedingly strong outer covering composed of stout pyramidal spikes, which grows upon the branches of a tall tree and occasionally in falling inflicts considerable injuries upon passers-by.
Hemiterpenes The best known is Isoprene, C 5 H 8, which is obtained on distilling caoutchouc or gutta-percha.
gutta-percha tube across a bare part of the steam pipe and melted it.
The great advantage of this air insulation is that the electrostatic capacity of the wires is low (about one-third of that which would be obtained with gutta-percha insulation), which is of the utmost importance for high-speed working or for longdistance telephonic communication.
The one disadvantage of paper cables is the fact that any injury to the lead covering which allows moisture to penetrate causes telegraphic interruption to the whole of the enclosed wires, whereas if the wires are each individually coated with gutta-percha, the presence of moisture can only affect those wires whose covering is defective There is no reason for doubting, however, that, provided the lead covering remains intact, the paper insulation is imperishable; this is not the case with gutta-percha-covered wires.
Of two transatlantic cables laid in 1894, the core of one consisted of Soo lb copper and 320 lb gutta-percha per mile, and that of the other of 650 lb copper and 400 lb gutta-percha; whereas for the similarly situated cable laid in 1866 the figures were 300 lb copper and 400 lb gutta-percha.
Vulcanized rubber is also now largely used as an electrical insulator for the construction of cables, &c., instead of gutta-percha.
The word usage examples above have been gathered from various sources to reflect current and historial usage. They do not represent the opinions of YourDictionary.com.