Identifier: dentaloral00mcco (find matches)
Title: Dental and oral radiography : a text book for students and practitioners of dentistry
Year: 1916 (1910s)
Authors: McCoy, James David
Subjects: Radiography, Dental X-rays Teeth Mouth
Publisher: St. Louis : Mosby
Contributing Library: West Virginia University Libraries
Digitizing Sponsor: LYRASIS Members and Sloan Foundation

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ratory of the TViirzberg Univer-sity. The experiment consisted of passing anelectric current through a Crookes tube coveredwith black cardboard, to test its florescence upona piece of cardboard coated with barium platino-cyanide. A fresh specimen of this chemical hadbeen prepared and spread upon the cardboardwhich was placed against the wall on the oppositeside of the room to dry. The room was darkenedand the current was passing through the tube,when to his amazement, Prof. Rontgen noticedthat the chemically covered cardboard on the oth-er side of the room was glowing with a wierd flo-rescence. He approached the cardboard and indoing so passed between it and the Crookes tube,and beheld his shadow upon the cardboard. Pick- 26 DENTAL AND ORAL RADIOGRAPHY ing np a book, he held it in front of the screenand noticed that it also cast a shadow. He thendiscovered that the luminous glow or florescenceon the cardboard appeared and disappeared withthe turning on and off of the current. With the
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Fig. 4.Ileinrich Hertz. tube operating, he picked np the cardboard andwhile examining it, noticed the shadow of his handon its surface, the bones appearing much darkerthan the soft parts of the hand. He also foundthat the florescence was produced in the card-board regardless of whether the chemically coated NATURE OF X-RAY AND ITS DISCOVERY 27 side was turned toward or away from the Crookestube, showing that the rays had the power to pene-trate substances at a distance from the tube. Further investigation proved that the radiationproducing these phenomena emanated from thepoint of impact of the cathode rays against theglass wall of the Crookes tube, that nearly all sub-stances were transparent to it, although in widelydifferent degrees, varying roughly with their den-sity; that the radiation was rectilinear, that itcould not be refracted, reflected, or deflected bya magnet. Hence it was plain to Kontgen thatthese rays were quite different from the cathoderays of Crookes, Hertz or Lena

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