Radium components: compounds of barium, which gave a brilliant green flame color, and unknown radioactive compounds which gave carmine spectral lines that had never been documented before. The Curies found the radioactive compounds to be very similar to the barium compounds, except that they were more insoluble. This made it possible for the Curies to separate out the radioactive compounds and discover a new element in them. The Curies announced their discovery to the French Academy of Sciences on 26 December 1898. The naming of radium dates to about 1899, from the French word "radium", formed in Modern Latin from "radius"
Modulated neutron initiator the force of conventional explosives. The initiator used in the early devices, located at the center of the bomb's plutonium pit, consisted of a beryllium pellet, and a beryllium shell with polonium between the two. The pellet, 0.8 cm in diameter, was coated with nickel and then a layer of gold. The beryllium shell was of 2 cm outer diameter with wall thickness of 0.6 cm. The inner surface of that shell had 15 concentric, wedge-shaped latitudinal grooves and was, like the inner sphere, coated with gold and nickel. A small amount of polonium-210 (50 curies, 11 mg) was deposited