René Just Haüy (French pronunciation:[aɥi]) FRS MWS FRSE (28 February 1743 – 1 June 1822) was a French priest and mineralogist, commonly styled the Abbé Haüy after he was made an honorary canon of Notre Dame. Due to his innovative work on crystal structure and his four-volume Traité de Minéralogie (1801), he is often referred to as the "Father of Modern Crystallography".[1] During the French Revolution he also helped to establish the metric system.
Haüy's interest in the services and music of the local church brought him to the attention of the prior of a nearby abbey of Premonstrants. Through him, Haüy was introduced to a colleague in Paris and obtained a scholarship to the College of Navarre. Haüy eventually became an usher, and in 1764, was appointed regent (master) of the fourth class.[2]
After his ordination, Haüy became regent (teacher) of the second class at the Collège du Cardinal-Lemoine.[2]
Through his friendship with his spiritual director, Abbé Lhomond, Haüy became interested first in botany, and after hearing a lecture by Louis-Jean-Marie Daubenton, in mineralogy.[3]
An accident apparently directed René-Just Haüy's attention to what became a new field in natural history, crystallography. Haüy was examining a broken specimen of calcareous spar in the collection of Jacques de France de Croisset. (According to some accounts, Haüy dropped the specimen and caused it to break.) He became intrigued by the perfectly smooth plane of the fracture.[3]
"The observation I have just noted is that which has served to develop my ideas on the structure of crystals. It presented itself in the case of a crystal that the citizen Defrance was kind enough to give me just after it had broken off from a group this enlightened amateur was showing me, and which formed part of his mineralogical collection. The prism had a single fracture along one of the edges of the base, by which it had been attached to the rest of the group. Instead of placing it in the collection I was then forming, I tried to divide it in other directions, and I succeeded, after several attempts, in extracting its rhomboid nucleus." René-Just Haüy, Traité de minéralogie (1801)[2]
Pearwood model of rock crystal rhomboid, made by René-Just Haüy, Teylers MuseumIntegrant molecules form a pentagonal dodecahedron of pyrite, Traité de minéralogie (1801)
Studying the fragments inspired Haüy to make further experiments in crystal cutting. Breaking down crystals to the smallest pieces possible, Haüy concluded that each type of crystal has a fundamental primitive, nucleus or “integrant molecule” of a particular shape, that could not be broken further without destroying both the physical and chemical nature of the crystal. He further argued that crystal structures are made up of orderly arrangements of these integrant molecules in successive layers, according to geometrical laws of crystallization.[5][3][6][4][7]
Crystals that had been classed together previously were identified as being of separate mineral species if their fundamental structure differed. Heavyspar, for example, was differentiated into specimens containing barium and strontium.[3]: 180
The value of Haüy's discovery was immediately recognized.[6]
Haüy with a contact goniometer, ca. 1812
Haüy and his contemporaries worked with limited evidence. They could observe a crystal's habit and cleavage planes and measure interfacial angles[5][7] with an instrument called a goniometer.[8] The internal structure underlying the crystal's integrant molecule would not be determinable until the development of X-Ray diffraction technology many years later, in 1902.[5][7] Haüy was not the only researcher to observe that calcite crystals could be composed of smaller rhombohedra, but it was he who introduced the idea of triple periodicity in crystals.[5]: 5–12 This idea was fundamental to later developments in the field on crystal lattices.[9]
Between 1784 and 1822, Haüy published more than 100 reports discussing his theories and their application to the structure of crystalline substances.[4]: 85
Haüy first stated his laws of decrement in Essai d'une théorie sur la structure des crystaux (1784). It was a radical departure from his previous works, introducing his theory of molé constituantes or constituent molecules.[5]: 322 By 1792, he had identified a number of parallelepipeds as possible primitive crystal forms.[5]: 326 Haüy worked out the mathematical theory of his work in his Traité de minéralogie (1801), which became a classic in the field.[6] By then, Haüy had applied his ideas to the differentiation of different species. He systematically described all the known minerals, sorting them into classes, and giving their chemical and geometrical properties.[5]: 328 His work, in four volumes, including an atlas of plates, was accounted among the most wonderful of the 19th century.[6]: 2 It has been described as "a work of comprehensive insight, and much of it, written with literary fluency".[10] A second updated edition appeared as Traité de cristallographie in 1822.[5]: 328
Haüy is also known for his observations on pyroelectricity. He detected pyroelectricity in calamine, an oxide of zinc, as early as 1785.[12]
He studied pyroelectricity in a number of other minerals including tourmaline and related them to crystalline structure.[13] He showed that electricity in tourmaline was strongest at the poles of the crystal and became imperceptible at the middle.[3]: 182–183 Haüy published a book on electricity and magnetism, Exposition raisonné de la théorie de l'électricité et du magnétisme, d'après les principes d'Æpinus, in 1787.[4]
On February 12, 1783, Haüy was elected to the Académie royale des sciences de Paris (French Academy of Sciences) with the rank of an adjoint in botany, there being no vacancy in either physics or mineralogy. In 1788, he became as an associate in natural history and mineralogy.[2]
On August 8, 1793, in spite of the efforts of Antoine Lavoisier, the Académie royale des sciences de Paris was dissolved by the National Convention.[16][17] It was not restored until August 22, 1795, when it became known as the Institut National des Sciences et des Arts (National Institute of Sciences and Arts).[17][18]
Before its suppression, the Academy of Sciences had formed a working group to develop a uniform system of weights and measures for use throughout France. Lavoisier was a major proponent, and on March 30, 1791, he submitted a plan on behalf of the Commission on Weights and Measures, which was adopted by the Constituent Assembly. Lavoisier and Haüy were tasked with determining the density of water. As of January 4, 1793, they determined the weight of a cubic decimeter of distilled water at the temperature of melting ice, the kilogram.[19]
On August 1, 1793, the National Convention passed a decree, in favor of developing uniform weights and measures across France. On September 11, 1793, they established a Temporary Commission of Weights and Measures made up of twelve scientists, including Haüy, whose task was to carry out the decree.[19]: 155 [20]
The work of the commission was disrupted by political events. In November 1793, Lavoisier and several others were arrested and removed from the Commission. On May 8, 1794, Lavoisier was guillotined.[21]
Nonetheless, Haüy remained secretary of the Commission through this turmoil.[4] The law of 18 Germinal an III was enacted on April 7, 1795, formally establishing the metric system in France.[19]
On July 12, 1794, a public decree reorganized the École des Mines (School of Mines) in Paris and specified the establishment of a Cabinet of Mineralogy, a collection of all Earth materials. In October 1794, René Just Haüy was appointed the first curator of the Cabinet of Mineralogy, later known as the Musée de Minéralogie. He may therefore be considered a founder of the Musée de Minéralogie.[22]
Haüy's work was appreciated by Napoleon, who made Haüy an Honorary Canon of the Eglise Métropolitain de Paris (Notre Dame) on April 5, 1802.[23] On November 28, 1803, Haüy became one of the first recipients of the Order of the Légion d'Honneur.[23] Napoleon encouraged Haüy to write Traité élémentaire de physique (1803), and is reported to have read it during his incarceration on Elba in 1814.[2] During his brief return to power in 1815, Napoleon promoted Haüy to officer of the Légion d'Honneur.[2]
After 1814 Haüy was deprived of his appointments by the Restoration government. He spent his final days in poverty, dying in Paris on June 1, 1822, even if "June 3" is systematically reported.[5] The confusion in Haüy's death date (June 1 instead of June 3) is an 1823 error by Cuvier, rectified in 1944 by A. Lacroix[24] but still often misreported.
His name is the thirteenth inscribed on the south-east side of the Eiffel Tower.[26]
The mineral Haüyne was named for Haüy in 1807 by Thomas-Christophe Bruun-Neergaard. It occurs in silica-deficient igneous rocks in a wide variety of locations.[27][28]
Traité de cristallographie (2 vols, 1822) Google Books
He also contributed papers, of which 100 are enumerated in the Royal Society's catalogue, to various scientific journals, especially the Journal de physique and the Annales du Museum d'Histoire Naturelle.
^ abChapin, Seymour L. (1968). "The Academy of Sciences during the Eighteenth Century: An Astronomical Appraisal". French Historical Studies. 5 (4): 371–404. doi:10.2307/286050. JSTOR286050.
^Bruun-Neergaard, Thomas-Christophe (1807). "De la Haüyne". Journal de Physique, de Chimie et d'Histoire Naturelle. LXV (July): 120–121. Retrieved 16 May 2018.
George F. Kunz. “The Life and Work of Haüy.” American Mineralogist. Volume 3, number 6, 1918. Pages 61–89, plates 5–11; Also: Bulletin of the New York Mineralogical Club. Volume 3, pages 61–89, plates 5–11 [sic]. This was for the celebration of the 175th anniversary of the birth of the famous French mineralogist.