• WordNet 3.6
    • n praseodymium a soft yellowish-white trivalent metallic element of the rare earth group; can be recovered from bastnasite or monazite by an ion-exchange process
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Webster's Revised Unabridged Dictionary
    • n Praseodymium (Chem) An elementary substance, one of the constituents of didymium; -- so called from the green color of its salts. Symbol Ps. Atomic weight 143.6.
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Century Dictionary and Cyclopedia
    • n praseodymium One of the two elements into which, in 1885, Auer von Welsbach succeeded in resolving what had previously been known as didymium. See neodymium. Praseodymium forms two oxids—Pr2O3, which is of a dingy greenish-white color, and PrO2, which is dark blackish-brown. The salts are bright leek-green when crystallized or in solution, and give an absorption-spectrum which contains few of the lines of the original didymium. A characteristic spark-spectrum can also be obtained. The atomic weight of praseodymium is 139.4 (H = 1) or 140.5 (O = 16).
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Webster's Revised Unabridged Dictionary
Praseo-, + didymium,


In literature:

Probably also Neodymium and Praseodymium are two of them, for their weights are 143.6, 140.5.
"Occult Chemistry" by Annie Besant and Charles W. Leadbeater
The atomic weight of praseodymium is 140.5.
"Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 4" by Various
Neodymium and Praseodymium discovered by Welsbach.
"The Progress of Invention in the Nineteenth Century." by Edward W. Byrn

In science:

The two cerium isotopes 147Ce and 148Ce wer discovered by Hofman and Daniels at Los Alamos Scientiļ¬c Laboratory in 1964: Some Short-Lived Isotopes of Cerium and Praseodymium .
Discovery of the Cerium Isotopes