<blockquote>Oneបើគេខ្ចប់បន្ទះថតរូប wraps a Lumière photographic plate with aជាមួយ bromide emulsion in two sheets of very thick black paper, such that the plate does not become clouded upon being exposed to the sun for a day. One places on the sheet of paper, on the outside, a slab of the phosphorescent substance, and one exposes the whole to the sun for several hours. When one then develops the photographic plate, one recognizes thatក្នុងសន្លឹកក្រដាសខ្មៅក្រាស់ពីរ theដែលយ៉ាងណាឱ្យបន្ទះនោះមិនស្រអាប់នៅពេលប៉ះនឹងពន្លឺព្រះអាទិត្យនៅពេលថ្ងៃ។ silhouetteគេដាក់នៅលើសន្លឹកក្រដាស ofនៅផ្នែកខាងក្រៅ theនូវបន្ទះសារធាតុពន្លឺផូស្វរមួយ phosphorescentហើយ substanceគេដាក់ទាំងអស់នេះ appearsឱ្យប៉ះពន្លឺថ្ងៃរាប់ម៉ោង។ inនៅពេលគេយកបន្ទះថតរូបនោះទៅផ្ដិត blackគេនឹងឃើញថា onស្រមោលនៃសារធាតុពន្លឺផូស្វរនោះ theលេចចេញជាពណ៌ខ្មៅនៅលើហ្វ៊ីល។ negative. If one places between the phosphorescent substance and the paper a piece of money or a metal screen pierced with a cut-out design, one sees the image of these objects appear on the negative. … One must conclude from these experiments that the phosphorescent substance in question emits rays which pass through the opaque paper and reduces silver salts.<ref>{{cite journal|author=Henri Becquerel|title =Sur les radiations émises par phosphorescence|journal=Comptes Rendus |volume = 122| pages = 420–421|year=1896|url=http://gallica.bnf.fr/ark:/12148/bpt6k30780/f422.chemindefer}}</ref><ref>''Comptes Rendus'' 122, 420 (1896), [http://web.lemoyne.edu/~giunta/becquerel.html translated by Carmen Giunta]. Accessed 10 September 2006.</ref></blockquote>
