File:A manual of practical medical electricity - the Röntgen rays and Finsen light (1902) (14783365842).jpg

Identifier: manualofpractica00turn (find matches)
Title: A manual of practical medical electricity : the Röntgen rays and Finsen light
Year: 1902 (1900s)
Authors: Turner, Dawson
Subjects: X-Rays Electrophysiology Electrosurgery Electric Stimulation Therapy Electrotherapeutics X-rays Electrophysiology Electrosurgery
Publisher: New York : William Wood & Company
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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de is a lead plate, and the positiveelectrode is a platinum wire; these are immersed in dilutesulphuric acid. When a difference of potential of not lessthan 30 volts is maintained between these electrodes, thecurrent that passes is interrupted very frequently; itmay be about 1,000 times a second. In consequence ofthis rapid rate of interruption, very powerful secondarydischarges are obtained, and these are of an almost con-tinuous nature (Fig. 144). There are several modificationsof the original form. There are, however, some objections 330 A Manual of Practical Medical Electricity to its use. It is not a steady and reliable interrupter ;sometimes it will give no trouble, while at other times itwill scarcely work at all. Further, it soon tires, and theacid becomes hot; the secondary discharges are also veryliable to melt the antikathode of the tube. It will notgive a long spark. 3. Lastly, there is a rubbing contact interrupter, whichI have been^ at work upon for a considerable period
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Fig. 143.—Wehnelt Interrupter. (Fig. 145). Believing that a rubbing contact between solidsgives a better contact, and a much cleaner and moresudden break than any contact and break between a solidand a liquid, I have endeavoured, in the following manner,to get over the difficulties that presented themselves.The chief difficulty to be overcome is the burning awayof the surfaces at the point where the current is broken.This can be diminished by immersing the separating RoNTGEi^ X Rays 331 surfaces in alcohol or petroleum, but it cannot be entirelyprevented, and a deep pit or groove is soon eaten out ofthe contact pieces. The pitting can also be diminishedby employing platinum or iridium surfaces, but the objec-tion to this is the great expense of these materials. A

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