Julius Lothar Meyer (19 August 1830 – 11 April 1895) was a Germanchemist. He was one of the pioneers in developing the earliest versions of theperiodic table of thechemical elements. The Russian chemistDmitri Mendeleev (his chief rival) and he both had worked withRobert Bunsen. Meyer never used his first given name and was simply known as Lothar Meyer throughout his life.

Lothar Meyer
Meyer in 1883
Born	Julius Lothar Meyer (1830-08-19)19 August 1830 Varel,Duchy of Oldenburg
Died	11 April 1895(1895-04-11) (aged 64) Tübingen,Kingdom of Württemberg
Nationality	German
Alma mater	University of Würzburg,University of Breslau
Known for	Periodic table ofchemical elements
Awards	Davy Medal(1882)
Scientific career
Fields	Chemistry
Institutions	University of Tübingen

Meyer was born inVarel, Germany (then part of theDuchy of Oldenburg). He was the son of Friedrich August Meyer, a physician, and Anna Biermann. After attending the Altes Gymnasium in Oldenburg, he studied medicine at theUniversity of Zurich in 1851. Two years later, he studiedpathology at theUniversity of Würzburg as a student ofRudolf Virchow. At Zurich, he had studied underCarl Ludwig, which had prompted him to devote his attention to physiological chemistry. After graduating as a Doctor of Medicine from Würzburg in 1854, he went toHeidelberg University, whereRobert Bunsen held the chair of chemistry. In 1858, he received a Ph.D. in chemistry from theUniversity of Breslau with a thesis on the effects ofcarbon monoxide on theblood. With this interest in thephysiology ofrespiration, he had recognized thatoxygen combines with thehemoglobin in blood.^[1][2]

Influenced by the mathematical teaching ofGustav Kirchhoff, he took up the study of mathematical physics at the University ofKönigsberg underFranz Ernst Neumann and in 1859, after having received hishabilitation (certification for university teaching), becamePrivatdozent in physics and chemistry at the University ofBreslau. In 1866, Meyer accepted a post at theEberswalde Forestry Academy at Neustadt-Eberswalde but two years later was appointed to a professorship at theKarlsruhe Polytechnic.^[3]

In 1872, Meyer was the first to suggest that the sixcarbon atoms in thebenzene ring (that had been proposed a few years earlier byAugust Kekulé) were interconnected by single bonds only, the fourth valence of each carbon atom being directed toward the interior of the ring.

During theFranco-Prussian War, the Polytechnic was used as a hospital and Meyer took an active role in the care of the wounded. In 1876, Meyer became Professor of Chemistry at theUniversity of Tübingen, where he served until his death from astroke on 11 April 1895 at the age of 64.^[3]

Meyer is best known for his part in the periodic classification of the elements. He noted, asJohn A. R. Newlands did in England, that if the elements were arranged in the order of their atomic weights, they fell into groups of similar chemical and physical properties repeated at periodic intervals. According to him, if the atomic weights were plotted asordinates and the atomic volumes asabscissae—the curve obtained a series ofmaxima and minima—the most electro-positive elements appearing at the peaks of the curve in the order of their atomic weights.^[3]

His book,Die modernen Theorien der Chemie, which he began writing inBreslau in 1862 and published two years later, contained an early version of the periodic table. It contained 28 elements, grouping them for the first time into six families by theirvalence. Works on organizing the elements byatomic weight, until then had been stymied by the widespread use ofequivalent weights for the elements, rather than atomic weights.^[5]

He published articles about classification table of the elements in horizontal form (1864) and vertical form (1870), in which the series of periods are properly ended by an element of the alkaline earth metal group.^[6]

In 1869,Dmitri Mendeleev published a periodic table of all elements known at that time (he later predicted several new elements to complete the table, and corrected some atomic weights). A few months later, Meyer published a paper that included a revised version of his 1864 table that now included virtually all of the known elements, which was similar to the table published by Mendeleev:^[7]

Meyer had developed his fuller periodic table independently, but he acknowledged Mendeleev's priority. Included in Meyer's paper was a line chart of atomic volumes as a function of atomic weights, showing graphically the periodicity of the elements. Like Mendeleev, he also included predictions of future elements, but unlike Mendeleev did not emphasize these predictions nor suggest details of the physical and chemical properties of the future elements.^[8]

In 1882, both Meyer and Mendeleev received theDavy Medal from theRoyal Society in recognition of their work on thePeriodic Law.

The mineral lotharmeyerite,CaZn₂(AsO₄)₂ · 2H₂O, was discovered in 1983 and named in recognition of Meyer's work on the Periodic Law. Thetype locality is theOjuela mine,Mapimí,Durango,Mexico.^[9] Four closely related minerals have been described since 1983: ferrilotharmeyerite (1992);^[10] cobaltlotharmeyerite (1997);^[11] nickellotharmeyerite (1999);^[12] and manganlotharmeyerite (2002).^[13]

Meyer married Johanna Volkmann in 1866.^[14]

On 19 August 2020,Google celebrated his 190th birthday with aGoogle Doodle.^[15]

• Dimitri Mendeleev
• History of the periodic table

• Chisholm, Hugh, ed. (1911)."Meyer, Julius Lothar" .Encyclopædia Britannica (11th ed.). Cambridge University Press.
• Seubert, Karl (1918)."Nekrolog: Lothar Meyer".Berichte der Deutschen Chemischen Gesellschaft.28 (4):1109–46.doi:10.1002/cber.18950280498.
• Harald Kluge and Ingrid Kaestner,Ein Wegbereiter der physikalischen Chemie im 19. Jahrhundert, Julius Lothar Meyer (1830–1895) (Aachen: Shaker-Verlag, 2014).
• Otto Kraetz, "Lothar Meyer,"Neue Deutsche Biographie, 17 (1994), 304–06.

• Works by or about Lothar Meyer at theInternet Archive
• Periodic table according to Lothar Meyer (1870)
• Video of a talk by Michael Gordin titled "Periodicity, Priority, Pedagogy: Mendeleev and Lothar Meyer"
• The Internet Database of Periodic Tables. Chemogenesis web book.
• "Meyer, Lothar Julius" .Encyclopedia Americana. 1920.