Plat"i*nous (?), a. (Chem.) Of, pertaining to, or containing, platinum;
-- used specifically to designate those compounds in which the element
has a lower valence, as contrasted with the platinic compounds; as,
platinous chloride (PtCl2).
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, intermediate in value between silver and gold, occurring
native or alloyed with other metals, also as the platinum arsenide
(sperrylite). It is heavy tin-white metal which is ductile and
malleable, but very infusible, and characterized by its resistance to
strong chemical reagents. It is used for crucibles, 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 194.3. Symbol Pt.
Formerly called platina.
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.
Plat"i*tude (?), n. [F., from plat flat. See Plate.] 1. The quality or
state of being flat, thin, or insipid; flat commonness; triteness;
staleness of ideas of language.
To hammer one golden grain of wit into a sheet of infinite
platitude.
Motley.
2. A thought or remark which is flat, dull, trite, or weak; a truism; a
commonplace.
Plat`i*tu`di*na"ri*an (?), n. One addicted to uttering platitudes, or
stale and insipid truisms. "A political platitudinarian." G. Eliot.
Plat`i*tu"di*nize (?), v. i. To utter platitudes or truisms.
Plat`i*tu"di*nous (?), a. Abounding in platitudes; of the nature of
platitudes; uttering platitudes. -- Plat`i*tu"di*nous*ness, n.