platinum metals

1 definition found

platinum metals - Collaborative International Dictionary of English v.0.48 :

  Platinum \Plat"i*num\, n. [NL., fr. Sp. platina, from plata
     silver, LL. plata a thin plate of metal. See Plate, and cf.
     Platina.] (Chem.)
     A metallic element of atomic number 78, one of the noble
     metals, classed with silver and gold as a precious metal,
     occurring native or alloyed with other metals and also as the
     platinum arsenide (sperrylite). It is a heavy tin-white metal
     which is ductile and malleable, but very infusible (melting
     point 1772[deg] C), and characterized by its resistance to
     strong chemical reagents. It is used for crucibles in
     laboratory operations, as a catalyst, in jewelry, for stills
     for sulphuric acid, rarely for coin, and in the form of foil
     and wire for many purposes. Specific gravity 21.5. Atomic
     weight 195.1. Symbol Pt. Formerly called platina.
     [1913 Webster +PJC]
  
     Platinum black (Chem.), a soft, dull black powder,
        consisting of finely divided metallic platinum obtained by
        reduction and precipitation from its solutions. It absorbs
        oxygen to a high degree, and is employed as an oxidizer.
        
  
     Platinum lamp (Elec.), a kind of incandescent lamp of which
        the luminous medium is platinum. See under Incandescent.
        
  
     Platinum metals (Chem.), the group of metallic elements
        which in their chemical and physical properties resemble
        platinum. These consist of the light platinum group, viz.,
        rhodium, ruthenium, and palladium, whose specific
        gravities are about 12; and the heavy platinum group,
        viz., osmium, iridium, and platinum, whose specific
        gravities are over 21.
  
     Platinum sponge (Chem.), metallic platinum in a gray,
        porous, spongy form, obtained by reducing the double
        chloride of platinum and ammonium. It absorbs oxygen,
        hydrogen, and certain other gases, to a high degree, and
        is employed as an agent in oxidizing.
        [1913 Webster]