NA rURE 



^9. 



THURSDAY, JUNE 27, iJ 



SCIENTIFIC WORTHIES. 

 XXVI.— Dmitri Ivanowitsh Mendeleeff. 



DMITRI IVANOWITSH MENDELEEFF was born 

 on February 7 (N.S.), 1834, at Tobolsk, in Siberia. 

 He was the seventeenth and youngest child of Ivan Paolo- 

 witsh Mendeleeff, Director of the Gymnasium at that place. 

 Soon after the birth of Dmitri his father became blind, and 

 was obliged to resign his position, and the family became 

 practically dependent upon the mother, Maria Dmitrievna 

 Mendeleeva — a woman of great energy and remarkable 

 force of character. She established a glass-works at 

 Tobolsk, the management of which for many years de- 

 volved entirely upon her, and on the profits of which she 

 brought up and educated her large family. The story of 

 Mendeleeff's youth is given in the preface to his great 

 work *'0n Solutions," which he dedicated to the memory 

 of his mother in a passage of singular beauty and power. 

 Having passed through the Gymnasium at Tobolsk, 

 Mendeleeff, at the age of sixteen, was sent to St. Peters- 

 burg, with the intention that he should study chemistry 

 at the University, under Zinin. He was, however, trans- 

 ferred to the Pedagogical Institute, the aim of which was 

 to train teachers for the District or Governmental Gym- 

 nasiums throughout the Empire. The Institute (which 

 was abolished in 1858) was established in the same build- 

 ing as the University, and was divided into two Facul- 

 ties — Historicophilological and Physico-mathematical. 

 Mendeleeff attached himself to the natural sciences, 

 and thus came under the influence of Woskresenky in 

 chemistry, of Emil Lenz in physics, of Ostrogradsky 

 in mathematics, of Ruprecht in botany, of F. Brandt 

 in zoology, of Kutorga in mineralogy, and of Sawitsh 

 in astronomy, most of whom were Professors of the 

 same sciences in the University. Whilst at the In- 

 stitute he wrote his first paper on " Isomorphism," 

 and on the termination of his course of instruction he 

 was appointed to the Gymnasium at Simferopol, in 

 the Crimea. During the Crimean war he was transferred 

 to one of the Gymnasiums at Odessa, and in 1856 he 

 was admitted to the degree of Magister Chemia of the 

 Physico-mathematical Faculty of the University of St. 

 Petersburg, and was made Privat-Docent in the Univer- 

 sity. Even at this early period of his career we find 

 Mendeleeff speculating on the great problems with which 

 his name is inseparably connected. The relations 

 between the specific gravities of substances and their 

 molecular weights had begun to attract increased atten- 

 tion. Kopp had just published the first instalment of 

 that long and laborious series of experimental obser- 

 vations which constitutes the real foundation of all our 

 knowledge concerning the specific volumes of liquids, 

 when the young Siberian philosopher laid a number of 

 theses on problems relating to specific volumes before the 

 Physico-mathematical Faculty of the University. He 

 pointed out that magnetic elements have smaller specific 

 volumes than diamagnetic elenients. He also showed 

 that Avogadro's supposition, that electro-positive elements 

 have larger specific volumes than electro-negative ele- 

 VOL. pCL.— No. 1026. 



ments, was in accordance with the greater number of 

 well-established facts. When we remember how slowly, 

 in spite of the powerful advocacy of Williamson, the 

 ideas of Laurent and Gerhardt and what came to be 

 known as the modern French school, found favour in this 

 country, it is remarkable, as indicating the radical and 

 progressive character of his mind, and the keenness of his 

 mental vision, to fina Mendeleeff, as far back as 1856, 

 insisting that to Gerhardt was due the best mode of de- 

 termining the chemical molecule ; that the molecule of 

 oxygen was expressed by the symbol O2 ; those of arsenic 

 and phosphorus by AS4 and P4 respectively ; that of 



alcohol by ^2^5 1 O; and that of ether by ^2^5 | q. 



Mendeleeff's researches on specific volumes were 

 begun in 1855, ^i^d were continued, with intermissions, 

 down to [1870; but part only of the work has been pub- 

 lished. In 1859, Mendeleeff obtained permission from 

 the Minister of Public Instruction to travel, and repaired 

 to Heidelberg, where he established a small private 

 laboratory, and occupied himself with the determination 

 of the physical constants of chemical compounds. He 

 returned home in 1861, and in 1863 was named Professor 

 of Chemistry at the Technological Institute of St. Peters- 

 burg. In 1866 he became Professor of Chemistry at the 

 University, and was made Doctor of Chemistry after a 

 pubhc defence of his dissertation " On the Combinations 

 of Water with Alcohol." He is now Emeritus Professor, 

 and delivers annually a course of lectures on general 

 chemistry. 



Mendeleeff is so prolific a writer that it is impossible 

 within the limits of an article of this kind to do justice to his 

 work. There is, in fact, no section of chemical science which 

 he has not enriched by his contributions. Some of his 

 earliest work related to questions of mineralogy and che- 

 mical geology ; and at times, as in his papers on CEnan- 

 thol-Sulphurous Acid, on Fermentation Propyl Alcohol, 

 and on the Nitriles, he cultivated the rapidly extending do- 

 main of organic chemistry. But his reputation mainly rests 

 upon his contributions to physical chemistry and to chemical 

 philosophy. In his papers on Specific Volumes he extends 

 Kopp's generalizations, and traces the specific volumes of 

 substances through various phases of chemical change. 

 He shows that in the thermal expansion of homologous 

 liquids the expansion-coefificient diminishes in a regular 

 manner as the series is ascended, and he indicates the 

 intimate connection which exists in the case of liquids 

 between expansion and cohesion, and the role played by 

 molecular cohesion in the determination of chemical 

 activity. His paper on the thermal expansion of liquids 

 above their boiling-points is noteworthy as demon- 

 strating that the empirical expressions given by Kopp, 

 Pierre, and others, for the expansion of liquids up to 

 their boiling-points, are equally applicable to far higher 

 temperatures, and that the expansion-coefficient gradually 

 increases with the diminution in molecular cohesion of 

 the liquid, until, in the case of certain liquids, e.g. ether 

 at 133°, it becomes even greater than that of the gas. 

 The expansion-coefificient of ether increases to o'oo54 at 

 the temperature of its absolute boiling-point— \^2X is, at 

 about 190°. The absolute boiling-point is defined by 

 Mendeleeff as that temperature at which the cohesion and 

 latent heat of vaporization are nil, and at which the liquid 



K 



