A manual of practical medical electricity - the Röntgen rays and Finsen light (1902) (14781304384)

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

Text Appearing Before Image:

Fig. -Six Cells in Compound Connection. resistance is very low, the internal resistance must also bemade low if satisfactory heating power is to be obtained.The most economical method will, however, be to chooseunder all circumstances cells, other things being equal,with as low an internal resistance as possible, and thereforeas large as may be convenient; for it is evident that what- 74 A Manual of Practical Medical Electricity ever energy is expended in overcoming an excessive in-ternal resistance is wasted, and that only that amount ofenergy which would be occupied in overcoming the lowestconvenient internal resistance can be considered to beusefully employed. High internal resistance is never anadvantage, though when the external resistance is alsohigh it may not be a material disadvantage.

Text Appearing After Image:

Fig. 34.—Six Cells in Compound Connection. Large cells have also other advantages : they are moreeasily attended to and cleaned, are more durable, and,containing a larger suppty of electrolyte, depolarizer,and bigger plates, they give a more constant current andare not so easily exhausted. When, however, a portablebattery is required, small cells are essential. Current-Strength 75 III.—Electrolysis. How should we arrange our cells for electrolyzingtumours ? In electrolysis the resistance will vary withthe position of the poles. If one pole be placed on theskin, and the other plunged into the tumour, the resist-ance will be much greater than it would be if both poleswere passed into the tumour, because in the latter case theresistance of the skin would be eliminated. The resistanceof the blood in an aneurism, when both poles are inserted,is about eight ohms according to Bartholow, though frommy own observations in measuring the resistance of bloodclot and blood serum I should imagi

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1902

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