File:A manual of practical medical electricity - the Röntgen rays and Finsen light (1902) (14783376472).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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ows of the sternum and vertebralcolumn, the shadow of the conical bullet could be mostdistinctly seen (Fig. 146). By means of the screen, many experiments can be per-formed much more expeditiously than by using a photo-graphic plate ; thus, .the transparency of various objectscan be at once estimated by placing them between thetube and the screen. All the heavy metals are opaque,but the lighter ones, such as aluminium, sodium, andlithium, are transparent ; wood, paper, books, and organicsubstances are more or less transparent. Rontgen foundthat the rays would traverse packs of cards and verythick volumes. Little can be added to the general law helaid down, that the opacity varies directly with thedensity ; we should now say with the atomic weight. Thus, metallic objects in a wooden box or a leathernpurse can be immediately made out (Fig. 149) ; the bonesof the forearm can be distinguished almost as well throughthe sleeve of the coat as when the arm is bare. Diamonds RoNTGEN X Rays 351
Text Appearing After Image:
Fig. 165.—Injected Bloodvessels of Heart. 352 A Manual of Practical Medical Electricity and precious stones are, as a rule, far more transparentthan their glass imitations, so that the latter can beimmediately detected. Fig. 148 is a photograph taken bythe author of a pair of diamonds, of emeralds, of rubies,and of sapphires, with their paste imitations. Lastly, X rays will affect photographic plates. The plate need not, however, be exposed, for the vsivswill pass quite easily through the wooden shutter of thedark slide ; nor must a camera and lens be used, becausethe rays, as Rontgen pointed out, cannot be refracted, andthe only effect of the lens would be to throw a dark shadow,in consequence of its opacity. A dry plate is placed, usinga red light, in a dark slide or opaque paper envelope (thelatter is best), and is then brought out and placed under-neath the tube, and at a distance of about 6 to 14 inchesfrom it. There appears to be no advantage in using avery rapid plate ; a med

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