Dmetri's illness did not improve. His doctor suggested that he had tuberculosis and that, at most, he had two years to live providing he moved to a more suitable climate. Mendeleev already had his life's ambitions in mind and, hoping to extend his life as long as possible, he moved to Simferopol in the Crimean Peninsula near the Black Sea in 1855 as chief science master of the gymnasium. He was 21 years old. At this point in his life he was driven by "the vision of the Russian people whom he knew he could aid through science." Needless to say, his move to the south was very beneficial. He progressively regained his strength to the point where the doctors found no sign of tuberculosis in his system.
In 1856, Mendeleev returned to St. Petersburg and defended his master's thesis: "Research and Theories on Expansion of Substances due to Heat." Following his masters program, Dmetri focused his life on his career of teaching and research. He was essentially a teacher devoted to his work and to his students; he was next a lover of his country and of his fellow men. The first led to his books and the periodic table, while the latter gave rise to his studies of chemical technology and the organization of Russia's industries, agriculture, transport meteorology and metrology. (17)
In 1859, he was assigned by the Minister of Public Instruction to go abroad to study and develop scientific and technological innovations. Between 1859 and 1861 he studied the densities of gases with Regnault in Paris and the workings of the spectroscope with Kirchoff in Heidelberg. He also pursued studies of capillarity and surface tension that led to his theory of "absolute boiling point," later known as critical temperature. While in Heidelberg he made the acquaintance of A.P. Borodin, a chemist who was to achieve greater reknown as a composer.(9) In 1860 at the Chemical Congress at Karlsruhe, Mendeleev had the opportunity to hear Cannizzaro discuss his work on atomic weights. These people greatly influenced the work which Mendeleev would pursue the rest of his life.
Following his trip abroad, the Russian chemist returned to his homeland where he settled down to a life of teaching and research in St. Petersburg. In 1863 he was named Professor of Chemistry at the Technological Institute and, in 1866, he became Professor of Chemistry at the University and was made Doctor of Science for his dissertation "On the Combinations of Water with Alcohol". As will be seen, his research findings were expansive and beneficial to the Russian people. Dmetri was always in touch with the classroom. Much of his lab work, including that on the periodic chart, occurred in his spare time following his lectures. He truly enjoyed educating the people, and they, in turned enjoyed his efforts:
...For me it was a revelation, a beautiful improvisation, a stimulant to the intellect which left deep traces on my development. (16)
Mendeleev not only taught in the university classrooms but anywhere he travelled. Many excerpts discuss his journeys by train where he would travel third class with the mouzhiks (peasants). It was on those journeys that he would share his findings about agriculture with the peasants over a cup of tea. The admiration that Mendeleev had for the people of Russia was reciprocated by the people. On the trains the mouzhiks would all gather round to see and talk with the man. The university students also adored him. Crowds of students would fill lecture halls to hear him speak of chemistry.
For Mendeleev, science was always the most important subject, but in that time period of unrest, just as today, science could be expanded to the realms of politics and social inequality. Mendeleev was not afraid to express his views on these topics:
> There exists everywhere a medium in things, determined by equilibrium. The Russian proverb says, 'Too much salt or too little salt is alike an evil.' It is the same in political and social relations... It is the function of science to discover the existence of a general reign of order in nature and to find the causes governing this order. And this refers in equal measure to the relations of man - social and political - and to the entire universe as a whole. (16)
These profound thoughts of order led him to the discovery of the periodic law, among other things, but also led to his resignation from the University on August 17, 1890. Throughout his life he witnessed a country repressed and in turmoil. As he grew older and more famous, he used his new-found prestige and power to try to speak out against repression.
The most all penetrating spirit before which will open the possibility of tilting not tables, but planets, is the spirit of free human inquiry. Believe only in that. (16)
His resignation from the university came as the result of carrying a student petition to the Minister of Education. The Minister refused to acknowledge the requests, stating that Mendeleev should keep to teaching and not involve himself with students and politics. Mendeleev's final lecture at the University of St. Petersburg was broken up by police who feared that he might lead the students in an uprising.