In this paper, clarified are the motivation leading the development and the contrivance featuring the processes of Millikan's verification of the elementary electrical charge, with the expectation as a case study for the new implication of the experimental researches in early 20th century physics.
The controversy on the atomic theory, occurred in St.Louis Congress (1904), and Millikan's own photo-electric effect research drove him to the momentous question as to the reality of "the electron as the natural unit of electricity".
Throughout his observational process ―"seeing the electron―, the confidence in and the limiting factors of his experimental apparatus are particularly noteworthy, as well as the active figures in his experimental methods in this period (1906-1911), especially in the process of converting the capture of ions by water droplets, found in the balanced method, into the core of his next oil-drop method.
As to the process under consideration, his essential result was the direct verification of the atomic interpretation of both electricity and matter, confirmed independently of the uncertain theory of Stokes' law of fall of a small spherical body through a gas.
The author has examined the historical context of the first edition of Mendeleev's famous chemistrytextbook The Principles of Chemistry (Osnovy khimii) written during 1868-1871.
Mendeleev's career began in 1854, when he published his first scientific paper, and reached its first landmark in 1869, when he announced his discovery of the Periodic Law of the Elements.
Those years were the period of great change and reforms in Russia, beginning in the middle of the 1850's after the defeat in the Cremean War, and running its course by the end of the 1860's, climaxed by the emancipation of the serfs in 1861. It was also the time of change in chemistry the dispute over the merits of different atomic weight systems had been finally settled, the classical organic structural theory had emerged, and several systems of classifying all elements based on Cannizzaro?s new atomic weight system had been presented by several chemists.
The author has paid special attention to the objectives which the Russian chemists, including Mendeleev, were expected to achieve during 1860's. There were two: the practical and the theoretical. The practical objective was the education of qualified professionals for the new capitalistic production Russia then was in want of. The educational system, especially at higher level, was reorganized during this period, and enough number of Russian chemists acquired posts in the academic institutions, so that they could form the Russian Chemical Society in 1868 Their theoretical objective was to deal with the current theoretical problems as well as the experimental ones in chemistry to meet the needs of the period when the classical foundation of chemistry was about to be laid.
The author has shown that Mendeleev's famous textbook was the culmination of his work in regard to those two objectives. The Principles of Chemistry, offering an advanced way of systematization of inorganic chemistry, was the new textbook for universities urgently required by Russian society, and in the process of s writing the final step to the discovery of the' Periodic Law was taken.