Joseph Priestley

In 1885 C. A. von Welsbach isolated two elements as oxides, praseodymium (the word meaning green twin ) and neodymium (meaning new twin ), from a mixture of lanthanide oxides called didymia. The oxides can be transformed to fluorides by reaction with HF at 700°C (1,292°F), or with NH4HF2 at 300°C (572°F). The hydrated fluorides are then dehydrated in vacuo in a current of HF gas. The metals praseodymium and neodymium are obtained via metallothermic reduction with calcium at approximately 1,450°C (2,642°F), or via electrolytic reduction of the melts. The metals can also be obtained from anhydrous chlorides, obtained via reaction of the oxides with ammonium chloride at 350°C (662 °F), which are then reduced with lithium-magnesium at approximately 100°C (212°F). 

Praseodymium halides (except the fluoride), nitrate, and acetate are soluble. The hydroxide, carbonate, oxalate phosphate, and oxide compotmds are insoluble. Praseodymium s solutions and most of its solids are green. 

When oxo-compounds of Pr(III) are ignited in the atmosphere, a black oxide of composition Pr On (approximately) is obtained. Fluorocomplexes of Pr(IV) that have the compositions Na2PrF6, NayPtgFji, and PrF4 have been obtained. 

Maestro, P. (1998). From Properties to Industrial Applications. In Rare Earths, ed. R. S. Puche and P. Caro. Madrid Editorial Complutense. 

Moeller, Therald (1973). The Chemistry of the Lanthanides. In Comprehensive Inorganic Chemistry, ed. J. C. Bailar, Jr. H. J. Emeleus Sir Ronald Nyhohn and A. F. Trotman-Dickenson. Oxford, UK Pergamon Press. 

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Priestley, Joseph, Discourses on the Evidence of Revealed Religion," J. 

Priestley, Joseph, Experiments and Observations on Different Kinds of Air, ... 

PRIESTLEY, JOSEPH (1733-1804). Priestley was an English chemist who researched relationships among plants, air, and animals. After meeting Benjamin Franklin he became interested in science and the two men became lifelong friends. Priestley started doing chemical experiments as a hobby, but it soon became a passion. He had little scientific education but his observations were very keen. 

Dalton s most significant work was done between 1795 and 1805, but fame came later—when the importance of his atomic theory was realized. He became a member of the Royal Society in 1822, received its first Royal Medal in 1826, and was honored with a state pension in 1833, among other honors. He died on July 27, 1844, and 40,000 people attended his funeral. see also Berzelius, Jons Jakob Faraday, Michael Lavoisier, Antoine Priestley, Joseph. 

Priestley, Joseph. Philosophical Empiricism. Printed for J. Johnson, London. 1775. 

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