Radium seventh of a gram of radium. One kilogram of the Earth's crust contains about 900 picograms of radium, and one liter of sea water contains about 89 femtograms of radium. Radium was discovered by Marie Sklodowska-Curie and her husband Pierre Curie on 21 December 1898, in a uraninite (pitchblende) sample. While studying the mineral earlier, the Curies removed uranium from it and found that the remaining material was still radioactive. They separated out an element similar to bismuth from pitchblende in July 1898, that turned out to be polonium. They then separated out a radioactive mixture consisting mostly of two
Radium chloride effectuated by fusion under hydrogen chloride. Radium chloride can also be prepared by heating radium bromide in a flow of dry hydrogen chloride gas, or by dehydrating radium sulfate with dry air and then heating the sulfate in a stream of hydrogen chloride. Radium chloride is a colorless-white salt with a blue-green luminescence, especially when heated. Its color gradually changes to yellow with aging, whereas contamination by barium may impart a rose tint. It is less soluble in water than other alkaline earth metal chlorides – at 25 °C its solubility is 245 g/L whereas that of barium chloride is