After having graduated the MPI, Mendeleyev presented his dissertation, which was named Isomorphism in connection with other relations of crystal form to the composition. Isomorphism is an identity of crystal form under the difference in the solution. This phenomenon is extraordinarily widespread in the minerals. The work, made under the direction of professor A. A. Voskresensky, was of great importance for the future development of scientific interests of the young scientist. At the end of his life he wrote, In the Main Pedagogical Institute it was required to write a dissertation on ones own subject I have chosen isomorphism because I was interested in the things, which I had discovered by myself and the subject seemed to me to be important in natural historical sense The compiling of this dissertation involved me most of all to studying of chemical relations. Thus, it determined many things
Studying of isomorphism made Mendeleyev clarify the similarity and distinction between the chemical compounds, and 15 years later to discovery of the periodical law of chemical elements.
In spring of 1855 D. I. Mendeleyev successfully passed the finals in all subjects. Academician U. F. Frizsche, who was present at the final in chemistry, highly appreciated the Mendeleyevs knowledge and in his letter to the director of the MPI supported the idea of giving this graduate an opportunity to continue his research. In Frizsches opinion, Mendeleyev was to get a place for the future work in one of the universitys cities.
Mendeleyev, however, wasnt able to take advantage of the opportunity to stay at the institute because of the state of health. Already in 1853, having been ill with consumption, he got to the institute sick quarters. Then the physicians didnt hope already that he would get well again, but Dmitry Mendeleyev recovered and wrote to the doctor in charge of the case a report with a request to take the next exam.
After having finished his studies, Mendeleyev had been appointed as a teacher of gymnasium in the Crimea. Southern air was healthgiving for him. He was prescribed to go to Simferopol. But Mendeleyev couldnt start working: there was the Crimean war of the 18531856s, Simferopol was situated close to the battle-ground, and the gymnasium was closed. Dmitry Mendeleyev learned that there was a vacant post of teacher in Odessa.
During winter and spring of 1856 Mendeleyev worked as a chief teacher at the gymnasium attached to the lycee de Richelieu. His teaching was of a lively, original and creative nature. Except teaching according to the curriculum, he planned to write a guide for gymnasia, where, according to him, he planned to describe gases, liquids, geological materials, minerals, remains of the organic creatures, plants starting with the lower ones and animals starting with the human being as a type, who forms a special class, and to finish with geography.
Dmitry Mendeleyev not only took an active part in the work as a teacher of mathematics and physics and later of other natural sciences, but he also continued his research. The work generally named Specific Volumes was the logical continuation of studying isomorphism. This work was a many-sided research, which is possible to be considered as a peculiar scientific trilogy, devoted to the pressing questions of chemistry of the middle of the 19th century. The scientist addressed to the deeper study of the substance structure, to the problem of the atom and molecule volume. The work appeared to be not only deserving the presentation as a dissertation for the Masters degree, but right away it became the foundation of the second dissertation for the right to deliver lectures. After having come back to Petersburg from Odessa, the young scientist got an opportunity to stay in the capital and to get the post of professors substitute at the University.
In 1859 D. Mendeleyev got a permission for a foreign trip to improve in the sciences. He went abroad with a properly worked out original programm of the research. The theoretical idea of the close connection between the physical and chemical characteristics of the substance became its foundation. During this period Mendeleyev especially emphasized the research of the cohesion of the particles. He supposed to study them by measuring the surface tension of the liquids (the phenomenon of capillarity) at the different temperatures.
Dmitry Ivanovich wrote, Being sent oversea in 1859, I studied only the capillarity, supposing to find there the clue to the solution of many physico-mathematical problems; I intended to determine the interdependence between the particle volume and the cohesion; The measure of the solid cohesion, undoubtly, is an attribute more intrinsic than i. e. the boiling-point, and until now we have very few data about it.
Dmitry Mendeleyev left Petersburg without having any clear idea of a science center of Europe where he was going to work. In a month spent on travelling around different cities, he chose Heidelberg, in the well-known university of which worked R. Bunsen, G. Kirchhoff, E. Erlenmeyer and other prominent scientists.
Having settled down in Heidelberg, Mendeleyev right away decided to establish his own laboratory, since it was impossible to carry out such delicate experiments as capillary ones in the laboratory, offered him by R. Bunsen. While starting to work the scientist gave a great consideration to the acquirement of good measuring instruments and their thorough study. While working in Heidelberg, studying the interdependence of the particle volume and the cohesion and studying the capillarity, D. Mendeleyev worked out the system of metrology and created the unique measuring equipment. For instance, he developed a fundamentally new instrument for the determination of the liquid density, which was later named after him, densimeter of D. I. Mendeleyev.
Concerning the series of works of the 18501860s, connected with the research of liquids, Mendeleyev told about it at the end of his life: Being partly disappointed, I had absolutely given up this difficult subject, where, however, I was thinking independently. It is evident because I discovered the «absolute boiling-point». He succeeded to determine that liquid had turned to steam under a certain temperature, which was called by him the absolute boiling-point.
This discovery is the first important scientific achievement of Mendeleyev. Later, after the works of T. Andrews, another term firmed up in the science critical temperature. However, Mendeleyevs priority in the ascertainment of this significant phenomenon is nowadays undoubted and generally acknowledged.
Mendeleyevs works on the subject of capillarity, realized by him in Heidelberg, are the logical continuation of his previous research. After having analyzed the whole of the scientists works and plans at the end of the 1850s, it is possible to say that he longed for constructing the general system of physico-mathematical knowledge. Obviously, as a result of his research of the specific volumes the scientist made sure that knowledge about the atom size and the positional relationship of the particles wasnt enough for the complete explanation of chemical characteristics of substances. He came to a conclusion that they should be supplemented with the characteristics, which were defining the force of interaction of the particles. Mendeleyev tried to work out the main regulations of a special theoretical discipline molecular mechanics, which rests upon the three values: weight, volume and the force of interaction of the particles (molecules).
Maria Dmitrievna Mendeleyeva (nee Kornilyeva; 17931850), the mother of D. I. Mendeleyev. Unknown painter. Oil painting
Ivan Ivanovich Mendeleyev (17831847), the father of D. I. Mendeleyev. Unknown painter. Oil painting
The building of Tobolskaya gymnasium, where D. I. Mendeleyev was studying in 1841-1849
Gymnasium attached to the lycee de Richelieu in Odessa, where D. I. Mendeleyev was teaching in 1855-1856
The attempt to construct the molecular mechanics is very interesting. It is an example of the orientation of the scientists works to the significant theoretical generalizations. Though today this idea is only of a historical importance, nevertheless, it describes perfectly the independent approach of the scientist to the solution of the problems of the substance structure. In the middle of the 19
th
Participation in the International chemical congress, which took place on September, 3
rd
th
It is difficult to overestimate the meaning of the International chemical congress in the history of chemistry. There was accepted the common system of atomic weights and were defined the conceptions of the molecule and atom.
As stated above, the scientific conceptions, which had been generally acknowledged at the congress of 1860, appeared in Mendeleyevs research even before; the fundamentals of the molecular theory, as well as the principles of defining the molecular weight and density, were delivered by him at his lectures.
At the beginning of the 1860s another important event took place in the life of D. I. Mendeleyev. On April, 29
th
In spite of the difficult relationships with his wife, D. I. Mendeleyev always behaved towards the family very carefully and responsibly. Especially he loved children, he often said, Whatever I do and, however, Im busy, Im always happy when any of them comes to me. The only thing, which could interrupt his work, were the children. If he suddenly heard the childrens screaming or crying, right away he rushed to find out what had happened. He used to come running and frightened, screamed loudly and threateningly, but in no circumstances at the child, but at the nunny. The nunny experienced it almost always and the children never. Dmitry Ivanovich said, I experienced many things in my life, but I dont know the better happiness than to see my children next to me.
His niece Nadezhda Yakovlevna Kapustina-Gubkina remembered that he loved and worried not only about his own children. In Boblovo the estate purchased by D. I. Mendeleyev in 1865 on an equal footing with his friend N. P. Ilyin in summer there were having rest several families with their children. The kids were always around the master of the house, they used to walk with him on his household business. It was interesting for them to listen to the stories of Dmitry Ivanovich, to walk with him about the forest, to share with him their joys and sorrows.
N. Y. Kapustina-Gubkina remembered an episode, which had vividly illustrated Dmitry Ivanovichs delicacy towards the childs soul, his kindness, In the morning my elder brother and sister were teaching us in Russian and in French. I perplexed in my translation and my sister was keeping me for a long time under the lesson. Dmitry Ivanovich was passing by the sitting-room, where we were studying, and told my sister casually:
Why are you exhausting her over the book, Anyuta? Let her walk, she will have time.
Right away I ran away, but after forty years I remember how kind he was towards the childs soul.
D. I. Mendeleyev is a scientist, a teacher, a public figure
The 1860s became for Dmitry Ivanovich Mendeleyev the time of realization of the significant research of scientific and applied nature. Here the amazing correlation of theoretical works of the scientist and their practical application became apparent.
Later his son Ivan Dmitrievich Mendeleyev wrote about his father, I knew as though two Mendeleyevs. One of them was an assiduous collector of facts, a petty empiricist Wagner of Goethe, for whom the highest pleasure was the treatment of the number, piling of the data, examination of interesting individual features of the phenomena. Another one was the valorous Faust, passing away to the spirits world, to the world of ideas, to the world of general laws
In 1861, at the suggestion of the Public Good Publishing House, D. I. Mendeleyev wrote a manual of organic chemistry, which became the first Russian textbook on this subject. The basis of this manual was the series of lectures delivered by him in 18571858. The book was written during the extremely short term and it caused the broad response in the scientific and public groups. Mendeleyev was awarded to a prize of the Academy of Sciences, and in 1863 the second edition of the manual was published.
Mendeleyev also started to edit the Technical Encyclopedia in many volumes Technologies according to Wagner (Wagner J. R. Theorie und Praxis der Gewerbe: Hand und Lehrhuch der Technologie). Wagners Encyclopedia was published in Leipzig in 18571860 and had a great success in Europe. First, D. I. Mendeleyev decided to make a translation only because of the lack of money. He remembered, I started translating and completing the Technologies according to Wagner because it was paid (30 rubles per sheet), but then I was interested and made many additions
The work on editing this book took several years. Dmitry Ivanovich not just translated the Technologies from German, but he made a large amount of adjustments, sometimes completing the book with his own chapters. After all, the Technologies according to Wagner played a significant role in the choice of the future subject of the scientists research. In the third part of the Technologies there were discussed the scientific and technological problems, connected with alcohol production. The practical importance of precise data about the density of alcohol-aqueous solutions and theoretical meaning of these data combined in this question. Density had been always considered by D. I. Mendeleyev as the most important parameter of substance. By the middle of the 1860s the scientist started paying less attention to the edition of the Technologies according to Wagner and was more and more concentrated on the research of the alcohol-aqueous solutions.
In 1863, in connection with the development of the technology of alcohol-aqueous industry, Mendeleyev started a new big series of science works on this subject. On the first stage he was constructing the instruments for defining alcohol concentration alcoholometers. And on the next stage the thorough research of relative density of alcohol-aqueous solutions in the whole interval of concentrations under several temperatures. This experimental work became the foundation of the Doctoral thesis, which was presented by him to the Council of Petersburg University at the end of 1864 and was defended by him in 1865.
The research About the connection of alcohol with water contains the basic regulations of Mendeleyevs doctrine of the solutions and it especially determines the existence of water and alcohol connections. Here are the results of measuring the density of aqueous solutions of ethyl alcohol with 35 to 100 % of alcohol according to weight under five values of temperature (0°, 10°, 15°, 20° and 30 °C).
It is necessary to thank Dmitry Ivanovich Mendeleyev that Russia was possible to give the world its famous Russian vodka. V. Pohlebkin in his article, devoted to the Mendeleyevs research, wrote, D. I. Mendeleyev, who had taken part in his time in the creation of the contemporary scientific technology of vodka production, insisted definitely on making the general official name vodka as the most exactly expressing the character of the drink.