the French Academy of Sciences glow in the dark pebbles

By the end of 1895, the German physicist Roentgen discovered a highly penetrating radiation, due to the nature of it does not understand, so named X-rays. After the discovery of X-ray after the news spread, the whole world sensation. 

January 20, 1896, the French Academy of Sciences held a regular meeting on Monday, the famous mathematician, physicist Poincare introduced Roentgen's discovery, also exhibited an X-ray photograph. His report aroused great glow in the dark rock‍ interest of the participants. After the meeting, the French physicist Burke Harrell rushed back to his lab. He and his father have long been studying the fluorescence phenomenon, they found that some of the material in the sunlight emits fluorescence. This discovery led to many applications today: fluorescent lamp called, because it's inside of the tube is coated with phosphor; are coated with a phosphor dot on the 12 hour luminous watch, after daylight illumination after their night after listening to Poincare able luminous ...... reports Burke Harrell feel the need to verify whether the fluorescent substance can emit X-rays. 

In early February, Burke Harrell began his experiments. He took a bottle of fluorescent substance - a yellow-green potassium uranyl sulfate, a substance in the sunlight will fluoresce, Burke Harrell wanted to know whether they will also emit X-rays. He modeled Roentgen X-ray inspection method, the photographic film with a black wrap tightly, then pour a spoonful of phosphor on the parcel, and then get the sun go down while drying. glow in the dark pigments‍ Burke Harrell then pour the phosphor to go back to the bottle, then took the bag with a black wrap film into the camera darkroom, after flushing has been found photographic negatives, and spoon on top of it is that the phosphor geometry shadow. Burke Harrell knew that the sun and fluorescent light can not penetrate the black paper to make photographic film. Now the film is sensitive, and this shows the phosphor after the sun can really emit X-rays, X-rays can penetrate because only black paper to make photographic film. So Burke Harrell at a regular meeting of the Academy of Sciences on February 24, briefly reported the discovery.