Joens-Jacob Berzelius, the famous swedish chemist, was born on the 20th of August 1779. He studied at Upsala, where he was granted the doctorate in medecine (1804). Short after that, he was appointed to a chair at the university of Stockholm and dedicated himself, almost entirely, to chemistry. His course, illustrated by demonstrative experiments, became reknown troughout the chemical world. He was made a member of the Royal Academy of Sciences (1808) served as its president (1810), and was elected standing secretary (1818). Berzelius was an expert analyst ; he performed many quantative analysis. He was the discoverer of several new elements. The atomic weights, he had determined, appeared in his table (1818), with the new chemical symbols he had devised ; his electro-dualistic theory based on experiments, he had carried out with a large Volta pile, his new classification of minerals, based upon instead of physical properties on their chemical composition, he had established himself experimentaly, made him as the dominant figure of his time, despite the fact he was geographically distant from the principal chemical centers. Several belgians were among Berzelius's numerous pupils, colleagues and friends. B. Valerius translated his text-book from the german edition into the french (Brussels, 1838-1844). J. B. Van Mons, the father of the belgian chemists, introduced him as a foreign member of our Royal Academy (1817). P. Louyet, who was a young and trusty follower, wrote his biographical sketch (1849). M. Martens, as being an electro-chemist, was very familiar with the Swedish theory in this field, brought himself a valuable contribution to it and was also involved in the controversy, J. B. Dumas versus J. J. Berzelius, about the theory of substitution processes (1840). Last but not least, J. J. Stas and L. Melsens, two young coworkers of J. B. Dumas took an active part in this controversy, one of the most violent in the course of XIX century.