Several modifications were proposed, in one of which, intended for the heating of non-conducting substances, the electrodes were passed horizontally through perforations in the upper part of the crucible walls, and the charge in the lower part of the crucible was heated by radiation.
In diameter, and the smallest 2 in., are wrapped in asbestos, felt and other non-conducting materials, and are placed in wooden tubes laid under ground like water and gas pipes.
He covered the bulb of the thermometer with layers of non-conducting material and left it immersed at the desired depth for a very long time to enable it to take the temperature of its surroundings.
Cylinders, tanks and independent boilers should be encased in a non-conducting material such as silicate cotton, thick felt or asbestos composition.
Even if the expansion is adiabatic, in the sense that it takes place inside a non-conducting enclosure and no heat is supplied from external sources, it will not be isentropic, since the heat supplied by internal friction must be included in reckoning the change of entropy.
Following the suggestion of Cavendish, Irving made observations of deep temperature on Phipps's Spitsbergen voyage of 1773 with a valved water-bottle, insulated by non-conducting material.
Dwellings require careful construction, with thick walls and roofs of non-conducting material to keep out the heat-rays, and fans and punkahs are essential for the promotion of currents of air in the inhabited rooms. Personal protection, in the shape of thick pith topees, or cork helmets, and spinal pads, is necessary in the hot months, the clothing being light and loose and not too thin.
These vary in form, but essentially they consist of a stem of porcelain, coarse earthenware, glass or other non-conducting substance, protected by an overhanging roof or screen.
In order that the current should be maintained, and the electromotive force of the cell remain constant during action, it is necessary to ensure that the changes in the cell, chemical or other, which produce the current, should neither destroy the difference between the electrodes, nor coat either electrode with a non-conducting layer through which the current cannot pass.
These separators are carefully protected by non-conducting cement and wood lagging, and are closed at the top to prevent loss of heat; and they will run for many hours without requiring to be changed, the duration of the run depending on the quality of the liquor treated and amount of impurities therein.