The 19th century was mostly the time of making researches of electricity and magnetism. These were the leading branches of sciences of the century. Many decisive inventions were based on the achievements of these branches of sciences. The researches on the nature of electricity and magnetism influenced the better acquaintance of atomic occurrences and the world of microelements. The scientists elaborated many of the laws of the condition of the world's microstructure. At last in the 90s of the 19th century, electron, the first elementary molecule, was discovered.
Thomas Johann Seebeck who lived in the years 1770-1831 discovered the occurrence of the flow of current in the circuit made of two different metals or semiconductors the temperatures of contacts of which were different.
Andre Marie Ampere who lived in the years 1775-1836, described the magnetic field occurring around the conductor in which the electric current flowed.
Amadeo Avogadro Di Quaregna who lived in the years 1776-1856 studied molecules and their features. He formulated the law which said that in constant temperature and pressure the quantity of the molecules of gas taking up the same space is the same. He stated also that the gram - molecule of every substance contained the same number of molecules (that quantity, evaluated in the year 1906, was called Avogadro's number).
Hans Christian Oersted, who lived in the years 1777-1851, was the scientist who discovered the electric current's influence on the magnetic needle - it was the beginning of the researches of electromagnetism.
William Prout, the Briton, who lived in the years 1785-1850, was the other great atomist. In the year 1815 he submitted a proposition that everything consisted of hydrogen atoms. Looking for the simple description of the world he came to the opinion that hydrogen was the lightest element - its mass number equalled one - than all the others, heavier elements consisted of hydrogen atoms. That hypothesis was rejected when it appeared that the mass number of chlorine equalled 35,5; fact that chlorine consisted of two variants - two isotopes with different atomic weight - wasn't known then.
Michael Faraday was the great chemist and physicist, who lived in the years 1791-1867. He set to do a research on electrochemistry - he formulated the laws of electrolysis which let the processes of electrolysis be better understood . He systematised electrochemical terms. He studied electromagnetic connections (he invented transformer and dynamo). He considered the interaction was of atoms. He was of the opinion that the interaction is transported by the field; that means the ability of space to be distempered by some source. In his works he tried to explain the connection between an atom and electric forces.
Wilhelm Eduard Weber was the German physicist living in the years 1804-1891. As one of the first he made a theory of electricity and magnetism. That explained the most of the experimentally discovered occurrences. He believed that the flow of current in the conductor consisted of both plus and minus charges. Both flows were to go in the opposite directions.
Joseph Loschmidt, who lived in the years 1821- 1895 found the order of the magnitude of atoms (10-8 cm).
Rudolf Emanuel Clausius, who lived in years 1822-1888, was the German (born in Koszalin in Poland) physicist-atomist. Describing atom's motion he used mathematical laws of statistics. He discovered that the temperature of the body depended on chaotic movement of that body's atoms. He formed the second law of thermodynamics. According to it, the heat of the colder body can't flow spontaneously to the warmer body. Studying the chaotic movement of atoms he defined the mean free path i.e. the statistic distance which the molecule could cover between collisions.
James Clerk Maxwell, who lived in the years 1831-1879, formulated the law of the decomposition of gas molecular velocity (assuming that gas was composed of chaotically moving molecules). He studied internal friction in gases. Basing on atomistics, he explained the slowness of diffusion. The most important of Maxwell's works were the ones of electromagnetism. He gathered Faraday's theories and ideas and put them into a mathematic form. Maxwell equalised the electric and magnetic fields. He foresaw electromagnetic waves subsistence and evaluated the velocity of their propagation in the empty space - the speed of light.
Dmitri Mendeleev, was the great Russian chemist, who lived in the year 1834-1907. Writing a handbook for students, setting elements in the order by their atomic mass he discovered a simply relation - every eight elements had similar features. So he put the elements into eight columns. He didn't fill up all gapes because some of the elements were still unknown. In the year 1875 gallium, the new element was discovered. Not long later scandium and germanium were discovered too. Their subsistence and features Mendeleev predicted before. That was the proof that he was right making his table.
Johannes Diderik van der Walls, lived in the years 1837-1923. He was a Dutch scientist, who studied the forces subsisting between gas particles. He imagined those particles as balls between which there was an attractive force growing when molecules were approaching until putting them together. Taking these two forces into consideration let him put corrections into equation of gas law. He described in it the dependence between the pressure, volume and the temperature of the gas.
John William Strutt Rayleigh, the great scientist, who lived in the years 1842-1919, default with many problems of physics. Among the others, he tried to evaluate Avogadro's constant; he estimated quantities of the molecules of different compounds; he searched the occurrence of the surface tension, what let him evaluate the forces acted between the particles. In the year 1894 together with William Ramsay he discovered the first of the helium-group gasses - argon.
Ludwig Eduard Boltzmann, who lived in the years 1844-1906 was one of the most versatile physicists of the 19th century. He searched occurrences in gases; he described a more general law of the decomposition of gas molecular velocity (the Maxwell-Boltzman law). In his researches of thermodynamics he introduced the conception of probability. He worked out the equation of gas transport - the law describing distempers transported in different kinds of gases - changes of temperature, velocity, density. These distempers are transported by collisions between molecules. The equation formulated by Boltzmann let diffusion, viscosity, heat conduction be better understood. It let also explain the Hall effect (the formation of the electric field by the joint action of the outer magnetic field and the current flowing in the conductor).
Wilhelm Conrad Roentgen lived in the years 1845-1923. Among his other researches he studied the occurrence of cathode radiation. That occurred while the electric current flowed through the tube filled with rare gas. The tube started to illuminate to the negative electrode. Invisible rays coming out of the cathode were supposed to be responsible for that. He observed their interaction with metals. He noticed that fluorescent crystals, placed near the set of instruments used in the experiment, started to illuminate. That happened even when he conducted the experiment on the absolute darkness. That occurrence he tried to explain by the subsistence of an unknown mysterious, new kind of radiation - X-radiation. Roentgen discovered that the radiation was absorbed by different materials in a different degree. That let him make the first photo of alive person's hand skeleton.
Henri Antoine Becquerel, who lived in the years 1852-1908, tried to find out whether during fluorescence besides visible light there was also the X-ray emission. To check whether it was so, he used photographic plates wrapped in lightproof paper. X-rays could permeate the paper and blacken the plates. On the wrapped plates he put irradiated samples of uranium. Plates were blackened. Becquerel said that was because they sent X-rays. But a few days later he noticed that even non-irradiated samples of uranium provoked the same effect. That was the first time when radiation was described.
William Ramsay lived in the years 1852-1916. In 1894 both he and John Rayleigh both discovered a new element which Ramsay called argon. It didn't compound with any other elements and it didn't fit in the periodic table. The table had to be enlarged by one column. A year later Ramsay discovered another element of that group - helium and in 1898 he isolated all noble gasses occurring in the air; that is: argon, neon, helium, krypton, xenon and in 1910 - radon. Apart from these researches he tried to interpretate the Brownian movements explaining them as collisions of observed bodies and invisible particles of medium.
Hendrik Antoon Lorentz was a great scientist of the end of the 19th century. He lived in the years 1853-1928. He wanted to find the connection between the optical and electromagnetic occurrences. He created an electron theory describing electromagnetic occurrences in matter. In the theory he placed a formula defining the forces influencing the charge moving in the electric field. Today those forces we call the Lorentz force.
Heinrich Rudolf Hertz, lived in the years 1857-1925. He searched electromagnetic waves - he proved that a fast vibrating charge, just like Maxwell foresaw it, was the source of electromagnetic waves. He also simplified formulas of Maxwell. Hertz discovered also that some metals emit minus particles under the influence of ultraviolet radiation. He noticed that electrically neutral metals become plus charged after the exposure.
Svante August Arrhenius who lived in the years 1859-1925, was a Swedish scientist. He created a modern theory of dissociation. He was the first to describe the activity of ions in the solution.
Pieter Zeeman lived in the years 1865-1943. He discovered the effect of the fission of atoms spectrum when putting them in the outer magnetic field - the Zeeman effect.
The scientist of the 19th century explained many occurrences connected with electromagnetism and the kinetic theory of gases. X-raying was discovered. There appeared some new equipment based on electromagnetic occurrences. Soon they were used in practise in people's life and as the experimental equipment. At the and of the 19th century the first elementary molecule was finally discovered - the electron.
