(C. E.*)
[1] The more notable chemists of this period were Turquet de Mayerne (1573-1665), a physician of Paris, who rejected the Galenian doctrines and accepted the exaggerations of Paracelsus; Andreas Libavius (d. 1616), chiefly famous for his Opera Omnia Medicochymica (1595); Jean Baptiste van Helmont (1577-1644), celebrated for his researches on gases; F. de la Boë Sylvius (1614-1672), who regarded medicine as applied chemistry; and Otto Tachenius, who elucidated the nature of salts.
[2] This dictum was questioned by the researches of H. Landolt, A. Heydweiller and others. In a series of 75 reactions it was found that in 61 there was apparently a diminution in weight, but in 1908, after a most careful repetition and making allowance for all experimental errors, Landolt concluded that no change occurred (see ELEMENT).
[3] The theory of Berthollet was essentially mechanical, and he attempted to prove that the course of a reaction depended not on affinities alone but also on the masses of the reacting components. In this respect his hypothesis has much in common with the “law of mass-action” developed at a much later date by the Swedish chemists Guldberg and Waage, and the American, Willard Gibbs (see [Chemical Action]). In his classical thesis Berthollet vigorously attacked the results deduced by Bergman, who had followed in his table of elective attractions the path traversed by Stahl and S. F. Geoffroy.
[4] Dalton’s atomic theory is treated in more detail in the article ATOM.
[5] Berzelius, however, appreciated the necessity of differentiating the atom and the molecule, and even urged Dalton to amend his doctrine, but without success.
[6] The following symbols were also used by Bergman:—
which represented zinc, manganese, cobalt, bismuth, nickel, arsenic, platinum, water, alcohol, phlogiston.