Hauy ,.I. Rene Just, a French mineralogist, born at St. Just, near Beauvais, Feb. 28, 1743, died in Paris, June 3, 1822. He was born of humble parents, but his love for religious music attracted the attention of a priest, who, after giving him some instruction, procured him a situation in the choir of a church in Paris, whence he went to the college of Navarre and to that of Cardinal Lemoine. In the latter institution, where he became a teacher, he first acquired a love for botany; and accidentally entering the lecture room of Dau-benton, he conceived a passion for mineralogy, which shaped his course in life. The accidental dropping of a specimen of calcareous spar revealed to him the geometrical law of crystallization. Communicating his discovery to Daubenton, at the suggestion of Laplace, who saw its great importance, he laid it before the academy in 1781. His discovery met with bitter opposition'; but the only answer he made to his detractors was new researches and more careful study. From the date of his memoir on the schorls in 1784 commenced a new era in mineralogy; chemistry confirmed the teachings of crystallography, and an entirely new arrangement of minerals was the consequence.
During the revolution Hauy, who had received holy orders, was thrown into prison; but the exertions of Geoffroy Saint-Hi-laire obtained his release a few days before the massacre of September, 1792. In 1793 he was appointed one of the committee on weights and measures, and in 1794 keeper of the cabinet of mines. In the latter capacity he prepared his principal work, Traite de mineralo-gie (4 vols. 8vo, Paris, 1801), of which a portion had been published in a single volume in 1797. It is a complete exposition of the idea that the crystalline form should be the principal guide in the determination of mineralogi-cal species, elevating his favorite study at once into the class of exact sciences. In December, 1802, he was appointed professor of mineralogy in the museum of natural history. In answer to an application from government to prepare a treatise on physics for colleges, he published in 1803 his Traite elementaire de physique, which passed through three editions. The little emolument accorded to him under the empire he lost under the restoration, and in the latter part of his life he was cramped by poverty; but he endured it with cheerfulness, and was greatly respected by all who knew him.
He died from the effects of a fall, leaving as sole inheritance to his family his magnificent collection of crystals, the fruit of 20 years' labor; it is now preserved, in a room by itself, in the museum of natural history in Paris. Among his works, besides those above referred to, are: Essai d'une theorie sur la structure des cristaux (1784); Exposition de la theorie de l'electricite et du magnetisme (1787); De la structure consideree comme caractere distinctif des mineraux (1793); Caracteres physiques des pierres precieuses (1817); and Traite de cristallographie (1822). He also contributed numerous papers to many of the scientific journals of the day. He was a member of the French academy, and of the principal scientific and learned associations of Europe and America. II. Valentin, a brother of the preceding, celebrated as an instructor of the blind, and as the inventor of apparatus for their education, born at St. Just, Nov. 13, 1745, died in Paris, March 19, 1822. He was called in France the "apostle of the blind," and commenced his labors in their behalf in 1784. For an account of his career, see Blind.