JULIUS LOTHAR MEYER was born at Varel in Oldenburg, on August 19, 1830. After completing his school course in the Gymnasium. he studied in the University of Zurich from 1851 to 1853, then at Wurzburg from 1853 to 1854; from Wurzburg he went to Heidelberg, where he remained till the autumn of 1856, and from thence he migrated to Konigsberg, where he remained until Easter 1858. Meyer's original intention was to devote himself to medicine, and he graduated as Doctor in Medicine at Wurzburg on February 24, 1854. At Heidelberg he came under the influence of Buiisen, and his work became more and more chemical. At Konigsberg his studies were devoted mainly to mathematical physics, under the guidance of F. Neumann. In 1858 he took the degree of Ph.D. at Breslau; and on February 21, 1859, he received leave to teach chemistry and physics. From 1859 to 1866 Meyer was in charge of the chemical laboratory of the Physiological Institute at Breslau. In 1866 he was called to the Royal Prussian Forstakademie at Eberswalde, where he remained until 1868, when he went to the Polytechnikum at Carlsruhe. In 1876 Prof. Fittig was called from Tubingen to the University of Strassburg', and Lothar Meyer was appointed to fill the vacancy at Tubingen. He had nearly completed twenty.years work at Tubingen when the summons came. Cerebral apoplexy stopped his labors, on April 12 of this year; and, plotz- lich, 8anft, und schmerzlos, he passed. It was while teaching chemistry and physics at Breslau that Meyer published the first edition of the work on which his reputation as a philosophical chemist chiefly rests. “Die Moderiien Theorien del' Che- mie” appeared in 1864. A second edition was published in 1872; and since that time have appeared a third, fourth, and fifth edition. At the time of his death Meyer was engaged in the preparation of a sixth edition, which he intended to publish in three, more or less independent, parts. An English translation of the fifth edition, by Messrs. Bedson and Williams, appeared in 1888. In 1883 Profs. Meyer and Seubert recalculated the atomic weights of the elements from the original data, and laid all chemists under a debt of gratitude by publishing their results, under the title “Die Atomgewichte der Elemente aus den Originalzahlen neu berechnet.” Lothar Meyer was one of the earliest investigators of the relations between the properties and the atomic weights of the elements. In the first edition of his 44 Modernen Theorien “(published in 1864) he traced relations between the atomic weights and theehemical values of the elements; and in Decembei' 1869 appeared a memoir by him entitled “Die Natur der chemischen Elemente als Funktion ihrer Atomgewichte,” wherein he arranged the elements in order of atomic weights, in a single table, and indicated the periodic character of the dependence of properties on atomic weights. The clear enunciation, and the application in detail, of the most far-reaching generalization that has been made in chemistrysince the work of Dalton, must, undoubtedly, be credited to that great chemist Mende- leeff, but, nevertheless, a perusal of the controversy between Mendeleeff and Meyer shows, I think, that Meyer arrived at the fundamental conception.of the periodic law independently of Mendeleeff. Those who are interested in such controversies will find papers by Mendeleeff and Meyer in Berichte xiii, pp. 259, 1796, 2043 [1880]. In his discourse to the German Chemical Society on May 29, 1893, “Ueber den Vortrag der unorganischen Ohemie nach dem naturliehen Systeme der Elemente,” Meyer quotes the words which Laurent had used fifty years before concerning- organic chemistry, and applies them to the teaching of inorganic chemistry at the present time: Que l'arbitraire y r£gne sans partage. If th ese words can be ap plied to the teaching of inorganic and geiieral chemistry to-day, how much more fu11y and literally were they applicable at the time when the first edition of Meyer's “Die Modernen Theorien” appeared thirty years ago ! That book has probably done more than any other publication within the twenty years after 1861 to ad van ce the study of comparative chemistry; its influence on the concep- tion of ch emistry as an accurate an d orderly body of facts and principles has been very great, and has been wholly good. The labor bestowed on the preparation of the first edition of the “Modern Theories” must have been immense. The author speaks in his preface of rewriting the MS. three times. It is true that th irty years ago ph ysical chemistry was practi- cally non-existent, that the faets of organic chemistry could be mastered and h eld by a man wi than ordin ary memory, and that one might be a chemist without first being a mathematical physicist. But it is also true that the facts of inorganic chemistry had not been co-ordinated by the luminous conception of the periodic law, that there was a lack of clearness in the notions of most ch em i sts about the stru ctu re of organ ic compounds—for Kekule had not yet made his famous ride on the top of the Clapham omnibus—and that the many isolated facts regarding the i nfl u ence of temperature, ti me, and the masses of the reacting bodies on chemical changes had not been gathered together and illuminated by the law of mass action and the eon cepti ons ari si ng from, the applicati on s of this law. It was then that “Die Modernen Theorien” ap- ppared; and at once a flood of light was thrown on the whole domain of chemieal science. Old problemtl were made clear, and new problems were suggested. Chemistry entered on its modern phase. ' As the stud y of comparative ch em istry: progressed— a study which was introd need by the enunciation of the pe ri od i c law—it became necessary to know with accuracy the analytical ba^s whereon rested the values aceepted” for the atomic weights of the ele- me n ts. Hence Lothar Meyer was induced to de vote a l arge amount of labor to the somewhat thankless task of recalcul at i n g t hese val ues; the result of this work, carried out with the help of his colleague Prof. Seu- bert, a ppeared in 1883. This work recei ved additional value from the fact that it appeared almost at the same time as Clarke's “Reealculation of the Atomic Weights.” Every worker in this department has the data of all previous workers brought to his hand, and presen ted in the most manageable form. Besides these two treatises bearing on general ch emi stry, Lothar Meyer was an investigator in the s p h e re of ex peri m en tal chemistry. He has published m emoirs of su bj eets in al most every branch of th e science; on the atomic weight of beryllium, on determinations of vapor densities, on the combustion of carbon monoxide, on the preparation of hydriodic acid, on the t ransp i rat ion of gases, oil vari ous organic compounds, and on other matters. A great chemist has passed away from us; his work remains, and that work will ever be held in remembrance. M. M. PATTISON MUIR.