Science Fair Project Encyclopedia
Jean Baptiste André Dumas (July 14, 1800 - April 10, 1884), French chemist, best known for his works on organic analysis and synthesis, as well as the determination of atomic weights (relative atomic masses) by measuring vapor densities.
Dumas was born at Alais (Gard), becoming apprentice to an apothecary in his native town. In 1816 he moved to Geneva, where he attended lectures by M. A. Pictet in physics, C. G. de la Rive in chemistry, and Augustin Pyrame de Candolle in botany, and before he had reached his majority he was engaged with Pierre Prévost in original work on problems of physiological chemistry, and even of embryology. In 1822 he moved to Paris, acting on the advice of Alexander von Humboldt, where he became professor of chemistry, initially at the Lyceum, later (1835) at the Ecole Polytechnique.
In 1826, Dumas showed that in all elastic fluids observed under the same conditions, the molecules are placed at equal distances.
Dumas established new values for the atomic mass of 30 elements, setting the value for hydrogen to 1.
After 1848, he exchanged much of his scientific work for ministerial posts under Napoleon III. He became a member of the National Legislative Assembly. He acted as minister of agriculture and commerce for a few months in 1850-1851, and subsequently became a senator, president of the municipal council of Paris, and master of the French mint; but his official career came to a sudden end with the fall of the Second Empire. He died at Cannes.
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He was one of the first to criticise the electro-chemical doctrines of Jöns Jakob Berzelius, which at the time his work began were widely accepted as the true theory of the constitution of compound bodies, and opposed a unitary view to the dualistic conception of the Swedish chemist. In a paper on the atomic theory, published in 1826, he anticipated to a remarkable extent some ideas which are frequently supposed to belong to a later period; and the continuation of these studies led him to the ideas about substitution ( metalepsis ) which were developed about 1839 into the theory ( Older Style Theory ) that in organic chemistry there are certain types which remain unchanged even when their hydrogen is replaced by an equivalent quantity of a haloid element. Many of his well-known researches were carried out in support of these views, one of the most important being that on the action of chlorine on acetic acid to form trichloracetic acid - a derivative of essentially the same character as the acetic acid itself.
In the 1826 paper he described his method for ascertaining vapour densities, and the redeterminations which he undertook by its aid of the atomic weights of carbon and oxygen proved the forerunners of a long series which included some thirty of the elements, the results being mostly published in 1858-1860.
In 1833 he devised a method of estimating the amount of nitrogen in organic substances.
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