ELUYAR Y SUVISA (erroneously written D'ELHUYART), Fausto de (aylooyar'eesoovee'sah), Spanish chemist, born in Logrono, Spain, 11 October 1757 ; died in Madrid in 1833. After studying in Spain, he went to Paris, devoted himself to natural science, and was appointed professor of mineralogy at the seminary of Vergara when he was scarcely nineteen years old. Two years afterward he was sent by the Royal basque society to make special studies in the mineralogical academy of Freiberg, Saxony, and in the mineral region of that country, whence he returned in 1781 to Vergara, and again occupied his chair. During 1783'4, by order of the government, he made scientific explorations of the mountains of Biscay and Navarra, and, in company with his brother Juan (who was afterward director general of mines in New Granada, and died there), analyzed the German wolfram ore, discovering the new metal called tungsten in 1785.

In the same year he was sent by the Spanish government to study the new method of amalgamation, used by Born in Hungaria, where he remained two years, and married in 1786 the daughter of Maria Theresa's privy counselor, Raab. In 1788 he went to New Spain as president of the royal Supreme Court of mines, taking with him twenty-five German miners, to teach the new method of amalgamation. He improved and enlarged the mines of Zacatecas, Guanajuato, Sombrerete, Bolanos, Real del Monte, Regla, and Pachuca, and in 1792 established in the City of Mexico the Royal College of mines, taking the chair of chemistry until a special professor could be obtained. During his presidency he established a complete chemical laboratory, a physical cabinet, and collections of minerals and of models of machinery constructed in Mexico of beautiful native woods. Humboldt visited the College in 1803, and admired its completeness and scientitle merits. Eluyar's distinguished qualities were so much appreciated that, in 1797, when his term of nine years was about to expire, the junta general of the viceroyalty petitioned the king to reappoint him, with the rank of minister of the royal council of commerce, mines, and mints for New Spain.

After the rebellion of Iturbide and the independence of Mexico, Eluyar returned to Spain, and was there appointed general director and member of the council of mines (1823), which place he held until his death. Eluyar was the inventor of a hydraulic machine and the author of several works on mineralogy, mining, and mints, the principal ones being " Descubrimiento de un nuevo metal hecho en el analisis del Wolfram" (printed by the Basque society)" " Tratado sobre la nueva amalgamacidn del concejero Born" (printed by the Mineralogical society of Germany); " Plan y distribucidn para el Colegio Seminario de mineria de Mejico"; " Memoria sobre noticias de minas" (1793) • "Sobre una nueva mAquina hidrAulica del autor" (1805); " Discursos sobre la importancia y subsistencia del Real cuerpo de la mineria en Nueva Espafia" (1815); "Disertacion sobre recojet la moneda provisional, y sobre las casas de moneda provinciales ..... Discursos sobre la mineria, su gobierno en general, su estado actual en Nueva Espana y su conveniente reforma "; and "Indaga= ciones sobre el sistema de amonedacidn observado en Nueva Espana, su actual estado y producto" (1818).