Becquerel. I. Antoine Cesar, a French physicist, born at Chatillon-sur-Loing, March 7, 1788. He was educated at the polytechnic school, served with the army in Spain as an officer of engineers, and retired in 1815 with the rank of major. In 1819 he commenced the publication of his mineralogical and geological researches. In studying the physical properties of amber, he was led to experiment on the discilarges of electricity by means of pressure; and that was the starting point of almost all his subsequent investigations. He then observed the evolutions of electricity in ever-kind of chemical action. These researches led to the refutation of the "theory of contact," by which Volta explained the action of his pile or battery, and to the construction of the first electrical apparatus with a constant current. The discoveries in electricity made by Becquerel have been published in the Annates de physique et de chimie and in the Memoires de l'academie des sciences. His investigations enabled him to discover a very simple method of determining the temperature of the interior organs of men and animals. He made numerous physiological applications of this method, and discovered that whenever a muscle is contracted a certain amount of heat is evolved. Becquerel is also one of the creators of electrochemistry.

In 1828 he made use of this new science in the production of mineral substances, and in treating by the humid process the ores of silver, lead, and copper. For these researches he was elected member of the royal society of London, and in April, 1829, of the French academy of sciences. In 1837 the royal society awarded him the Copley medal for his numerous discoveries in science. He was appointed professor at the Paris museum of natural history the same year, and was promoted in 1865 to the rank of commander of the legion of honor. Among the list of new substances which Becquerel obtained by the action of electricity may be mentioned aluminum, silicon, glucium, crystals of sulphur and of iodine, and numerous metallic sul-phurets, such as dodecahedral pyrites, galena, sulphuret of silver, iodurets and double iodu-rets, carbonates, malachite, calcareous spar, dolomite, metallic and earthy phosphates and arseniates, crystallized silica, etc. He also discovered a process of electric coloring on gold, silver, and copper, which has been extensively and variously applied in practice.

In his electro-chemical investigations, Becquerel's object was to discover the relations existing between the electric forces and the so-called chemical affinities, and to excite the latter into action by means of the former. All kinds of plating with gold or silver by the humid process, such as electrotyping, are only so many various applications of electro-chemistry. Many of his researches relate to the electric con-ductibility of metals, galvanometers, the electric properties of tourmaline, atmospheric electricity, the effects produced by vegetation, the electro-magnetic balance, capable of measuring with exactness the intensity of electric currents, and to the use of marine salt in agriculture. Among his principal works are: Traite experimental de Pelectricite et du magnetisme (7 vols., Paris, 1834-'40; new ed., 2 vols., 1855); Traite de physique dans ses rapports avec la chimie (2 vols., 1842-'4); Traite de l'elec-tricite et du magnetisme (2 vols., 1855-'6); and Resume de l'histoire de l'electricite et du magnetisme (1858). II. Alexandre Edmond, son of the preceding, born in Paris, March 24, 1820. He was assistant professor of natural sciences at the museum, and afterward professor at the conservatoire des arts et metiers. In 1853 he was appointed professor of physical sciences.

In 1803 he was elected member of the academy as successor of Despretz. He discovered a chloride of silver which will receive and retain the colored impressions of light, so that the colors of the rainbow may now be fixed in the daguerreotype in all varieties of hue; but they can only be retained in obscurity, as they gradually disappear when long exposed to light. In 1862 he published Etudes sur l'exposition de Londres, the phosphoroscope of his invention having attracted much attention at the London exposition of 1861. He assisted his father in his later works. III. Louis Alfred, brother of the preceding, born in Paris in 1814, died in 18(52. He was a physician and a professor in the faculty of Paris, and author of many valuable treatises. His Semeiotique des urines (1841) won a prize from the academy; and a second edition of Des applications de Velectricite a la therapeutique medicale was published in 1861.