The Russian Federation. Акопян Л.Г. - 31 стр.

                                Dmitry Ivanovich Mendeleyev

     Dmitry Ivanovich Mendeleyev is a famous Russian chemist. He is best known for
his development of the periodic table of the properties of the chemical elements. This
table displays that element’ properties are changed periodically, when they are arranged
according to their atomic weights.
     Mendeleyev was born in 1834 in Tobolsk, Siberia. He studied chemistry at the
University of St. Petersburg, and in 1859 he was sent to study at the University of
Heidelberg. He returned to St. Petersburg and became Professor of Chemistry at the
Technical Institute in 1863. He became Professor of General Chemistry at the University
of St. Petersburg in 1866. Mendeleyev was a well-known teacher, and because there was
no good textbook in chemistry at that time he wrote the two-volume “Principles of
Chemistry” which became a classic textbook in chemistry. In this book Mendeleyev
tried to classify the elements according to their chemical properties. In 1869 he
published his first version of his periodic table of elements.
     In 1871 he published an improved version of the periodic table, in which he left
gaps for elements that were not known at that time. His table and theories were proved
later when three predicted elements: gallium, germanium and scandium were
discovered.
     Mendeleyev investigated the chemical theory of solution. He also investigated the
thermal expansion of liquids and the nature of petroleum.
     In 1893 he became director of the Bureau of Weights and Measures in St.
Petersburg and held this position until his death in 1907.

                              Kliment Arkadyevich Timiryazev

     Kliment Arkadyevich Timiryazev belongs to the scientists who are most popular
and most respected and honoured by the Russian people.
     He was born in St. Petersburg on the third of June, 1843. His parents, well-
educated and progressive people of the time directed his education and greatly
influenced his word outlook. Later Timiryazev dedicated his work «Science and
Democracy» to his parents. In his dedication he wrote that his parents had taught him to
love truth in everything.
     In 1868 after graduating from the Petersburg University he made a report on his
experiments in the field of plant nutrion from the air at the first Congress of Naturalists
in Petersburg. The same year he went abroad and worked in the laboratories of famous
scientists till 1870 when he returned to Russia and became the head at the Chair of
Botany at the Petrovskaya Academy.
     As a scientist Timiryazev was the researcher who devoted his life to solving one
and the same problem – the problem of photosynthesis. The problem is very important
because it is connected with the existence of life on the Earth. His brilliant lecture on the

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