See also:

• DIDYMIUM (from the Gr. &Segos, twin)

DIDYMIUM (from the Gr. &Segos, twin)  , the name given. to the supposed See also:

• ELEMENT (Lat. elementum)

element isolated by C . G . Mosander from cerite (1839-1841) . In 1879, however, Lecoq de Boisbaudran showed that Mosander's "See also:

• DIDYMIUM (from the Gr. &Segos, twin)

didymium " contained samarium; while the residual " didymium," after removal of samarium, was split by Auer v . Welsbach (Monats. f . Chem'ie, 1885, 6, 477) into two components (known respectively as neodymium and praseodymium) by repeated fractional See also:

• CRYSTALLIZATION

crystallization of the See also:

• DOUBLE
• DOUBLE (from the Mid. Eng. duble, the form which gives the present pronunciation, through the Old Er. duble, from Lat. duplus, twice as much)

double nitrate of ammonium and didymium in nitric See also:

• ACID (from the Lat. root ac-, sharp; acere, to be sour)

acid . Neodymium (Nd) forms the See also:

• CHIEF (from Fr. chef, head, Lat. caput)

chief portion of the old " didymium . " Its salts are reddish See also:

• VIOLET

violet in See also:

• COLOUR (Lat. color, connected with celare, to hide, the root meaning, therefore, being that of a covering)

colour, and give a characteristic absorption spectrum . It forms oxides of See also:

• COMPOSITION
• COMPOSITION (Lat. compositio, from componere, to put together)

composition Nd203 and Nd205, the latter being obtained by ignition of the nitrate (B . Brauner) . The atomic See also:

• WEIGHT

weight of neodymium is 143.6 (B . Brauner, Proc .

Chem . See also:

• SOC

Soc., 1897-1898, p . 70) . Praseodymium (Pr) forms oxides of composition Pr203, Pr206,xH2O (B . Brauner), and Pr407 . The peroxide, Pr407, forms a dark See also:

• BROWN
• BROWN, CHARLES BROCKDEN (1771-181o)
• BROWN, FORD MADOX (1821-1893)
• BROWN, FRANCIS (1849- )
• BROWN, GEORGE (1818-188o)
• BROWN, HENRY KIRKE (1814-1886)
• BROWN, JACOB (1775–1828)
• BROWN, JOHN (1715–1766)
• BROWN, JOHN (1722-1787)
• BROWN, JOHN (1735–1788)
• BROWN, JOHN (1784–1858)
• BROWN, JOHN (1800-1859)
• BROWN, JOHN (1810—1882)
• BROWN, JOHN GEORGE (1831— )
• BROWN, ROBERT (1773-1858)
• BROWN, SAMUEL MORISON (1817—1856)
• BROWN, SIR GEORGE (1790-1865)
• BROWN, SIR JOHN (1816-1896)
• BROWN, SIR WILLIAM, BART
• BROWN, THOMAS (1663-1704)
• BROWN, THOMAS (1778-1820)
• BROWN, THOMAS EDWARD (1830-1897)
• BROWN, WILLIAM LAURENCE (1755–1830)

brown See also:

• POWDER (through O. Fr. puldre, modern poudre, from Lat. pulvis, pulveris, dust)

powder, and is obtained by ignition of the oxalate or nitrate . The sesquioxide, Pr203, is obtained as a greenish See also:

• WHITE
• WHITE, ANDREW DICKSON (1832– )
• WHITE, GILBERT (1720–1793)
• WHITE, HENRY KIRKE (1785-1806)
• WHITE, HUGH LAWSON (1773-1840)
• WHITE, JOSEPH BLANCO (1775-1841)
• WHITE, RICHARD GRANT (1822-1885)
• WHITE, ROBERT (1645-1704)
• WHITE, SIR GEORGE STUART (1835– )
• WHITE, SIR THOMAS (1492-1567)
• WHITE, SIR WILLIAM ARTHUR (1824--1891)
• WHITE, SIR WILLIAM HENRY (1845– )
• WHITE, THOMAS (1628-1698)
• WHITE, THOMAS (c. 1550-1624)

white See also:

• MASS (O.E. maesse; Fr. messe; Ger. Messe; Ital. messa; from eccl. Lat. missa)
• MASS, IN

mass by the reduction of the peroxide . The salts of praseodymium are See also:

• GREEN, A
• GREEN, ALEXANDER HENRY (1832—1896)
• GREEN, DUFF (1791—1875)
• GREEN, JOHN RICHARD (1837—1883)
• GREEN, MATTHEW (1696-1737)
• GREEN, THOMAS HILL (1836-1882)
• GREEN, VALENTINE (1739–1813)
• GREEN, WILLIAM HENRY (.1825–1900)

green in colour, and give a characteristic spark spectrum . The atomic weight of praseodymium is 140'5 .