From the CRC handbook of Chemistry and Physics, CRC Press, Cleveland,  55th ed., 1974-75 "The Elements" by C.R. Hammond. page B-6
POLONIUM (Poland, native country of Mme. Curie), Po; at. mass. (~210); at. no. 84; m.p. 254 C; b.p. 962 C; sp.gr. (alpha modification) 9.32; valence -2,0,+2,+3(?),+4 and +6.  Polonium was the first element discovered by Mme. Curie, in 1898, while seeking the cause of radioactivity of  pitchblende from Joachimsthal, Bohemia.  The electroscope showed it separated with bismuth.  Polonium is also called Radium F.  Polonium is a very rare natural element.  Uranium ores contain only about 100 micrograms of the  element per ton.  Its abundance is only about 0.2% of that of radium.   In 1934 it was found that when natural bismuth (Bi(209)) was bombarded by neutrons, Bi(210), the parent of polonium, was obtained.  Milligram amounts of polonium may now be prepared this way, by using the high neutron fluxes of nuclear reactors.  Polonium-210 is a low-melting, fairly volatie metal, 50% of which is vaporized in air in 45 housrs at 55 C.  It is an alpha emitter with a half-life of 138.39 days.  A milligram emits as many alpha particles as 5 grams of radium.  The energy released by its decay is so large (27.5 calories per curie per day or 130 watts/gm.) that a capsule containing  about half a gram reaches a temperature abouve 500 C.  The capsule also  presents a contact gammaray dose rate of 1.2 roentgen per hour.  A few curies of polonium exhibit a blue glow, caused by excitation of the surronding gas. Because almost all alpha radiation is stopped within the solid source and its containter, giving up its energy, polonium has attracted attention for uses as  light-wieight heat source for thermoelectric power in space satellites.   Polonium has more isotopes than any other element.  Twenty-seven isotopes of polonium are known, with atomic masses ranging from 192 to 218.  Polonium-210  is the most readily available.  Isotopes of mass 209 (half-life of 103 yrs.) and mass 208 (half-life 2.9 yrs.) can be prepared by alpha, proton, or deuteron bombardment of lead or bismuth in a cyclotron, but these are expensive to  produce.  Metallic polonium  has been prepared from polonium hydroxde and  somne other polonium compounds in the presence of concentrated aqueous or  anhydrous liquid ammonia.  Two allotropic modifications are know to exit.   Polonium is readily dissovled in dilute acids, but is only slightly soluble  in alkalis.  Polonium salts of organic acids char rapidly; halide annines  are reduced to the metal.  Polonium can be mixed or alloyed with beryllium to provide a source of neutrons.  It has been used in devices for eliminating static charges in textile mills, etc.; however, beta sources are more  commonly used and are less dangerous.  It is also used on brushes for  removing dust from photographic films.  The polonium for these is carefully  sealed and controlled, minimizing hazards to the user.  Polonium-209 is very  dangerous to handle in even milligram or microgram amounts and special  equipment and strict control is necessary.  Damage arises from the complete  absorption of the energy of the alpha particle into the tissue.  The maximum  permissilbe body-burden for ingesting polonium is only 0.03 micro curies,  which represents a particle weighing only 6.8X10^12 grams.  Weight-for-weight  it is about 2.5X10^11 microcuries/cc.  Polonium is availabel commercially  on special order with an A.E.C. permit from the Oak Ridge National  Laboratory.