Handbook of Antistatics, Second Edition
Book PrefaceHandbook of Antistatics, Second Edition
Static electricity is not a phenomenon of modern times. When walking the coastline and searching for amber, the yellow or sometimes brownish shimmering fossilized resin of evergreen trees, one finds many similar materials looking like this ancient natural plastic, but to prove whether it is not just a colored stone or a piece of broken glass smoothed by waves, one has to dry it and rub it on clothes. If it then attracts small pieces of dry paper, it is almost certain that it is amber. The reason for attracting the pieces of paper is the electrostatic charging caused by friction. More than twenty-five centuries ago the Greek scientist Thales of Miletus (624 BC to 547 BC) observed that amber attracts small particles of dust when rubbed with animal fur.1 The Greek word “elektron” means amber, and amber gave its name to the negatively charged elemental particle. However, it required centuries to discover the origin and the nature of electrostatic charging.
William Gilbert (1544-1603), a London physician, discovered that beside amber, other materials could be charged to attract different objects. He called the attracting force “vis electrica”, and he distinguished between materials which behave like amber (“electriks”) and materials that could not be charged (“noelectriks”). Even if he did not discover the real nature of the electrostatic attraction, Gilbert discovered that it is different than “magnetic” attraction. Many scientists have been fascinated by the “electriks” and a large variety of impressive, sometimes curious apparatuses and experiments have been developed for demonstrating electrostatic phenomena over the years.2
Otto von Guericke (1602-1686) developed the first electric generator, which produced static electricity by applying friction rubbing against a revolving ball of sulfur. This electricity resulted in attractive but also in repulsive (“expulsiv”) forces, depending on the composition of the body brought into the neighborhood of the charged sulfur ball. The attractive or repulsive forces can be converted into each other by contact with the sulfur ball or contact with other bodies. Possibly Guericke was also the first man who viewed artificially produced electroluminescence when wrapping the sulfur ball with dry hands in the dark. Jean Picard (1620-1682), a Parisian astronomer, observed a lightning, which then was called “mercurial phosphor”, when mercury moved within a barometer. Based on this observation Francis Hauksbee (he probably died in 1713 in London) developed instruments for generation of light by electrification of glass tubes (initially with mercury in glass globes). Later he found that just the electrification of glass tubes due to rubbing is sufficient to create the glow inside the glass tubes or globes.
In 1729, the English physicist Stephen Gray (1666-1736) tried to convey the electric virtue produced by wrapping a glass tube to other bodies. When connecting an ivory ball (and later also other things) to the glass tube by a thread of hemp, the static electricity was transported to the ball, while when substituting hemp by a thin silk thread the ivory ball showed no electric attraction. Hemp acted as a conductor for electricity, while silk was an insulator (even if this term was not used by him). Furthermore, he discovered that distant objects (he did experiments with distances up to 200 meters) could be electrified only if the conducting thread is prevented from contact with earth by insulating materials such as silk threads. Continuing the studies of Gray, the French Scientist Charles François de Cisternay DuFay (often called Charles Dufay, 1698 – 1739) discovered that wet hemp threads conduct electricity better than dry threads and that all bodies can be charged electrically by heating and wrapping, except metals. However, all bodies (including metals) can be charged by influence. He observed that the harder it is to electrify the body, the stronger are their attractive forces. Furthermore, he found that the color of an object does not influence the electric properties but rather the matter from which the color is made. Most importantly, he discovered that there are two kinds of electricity, one produced by glass (“vitreous electricity”) and the other by resin (“resinous electricity”). When measuring if bodies are charged with vitreous electricity or with resinous electricity, he used a thread of silk which becomes resinous electric when wrapping. Bodies which repel this thread are resinous electric; bodies which attract the thread are vitreous electric.
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