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the deaths of Berthelot and Moissan, France has lost its most illustrious chemists and the world two of its leading men of science. At the celebration held at the Sorbonne in 1901 in honor of the jubilee of the scientific work of Berthelot, Moissan said in his address: "As soon as you touch a question you extend it by generalizing it." The two great chemists indeed typify the changing conditions of scientific performance and of the scientific career. The more than a thousand publications of Berthelot cover a great part of the field of chemistry ranging from minute researches to the widest generalizations. He was a historian, an archeologist, a man of letters, an educational administrator and a statesman as well as a chemist. Moissan, on the other hand, obtained eminence by methods which it appears must become more common with the increasing specialization of science—intensive work in a comparatively narrow field.

Marcelin Pierre Eugène Berthelot was born eighty years ago, the son of a physician. His first scientific work, published in 1850, was on a method of liquefying gases. His thesis for the doctorate was on glycerine and the fats, opening up important questions in organic chemistry, which he followed by his work in synthesizing fundamental organic compounds, such as alcohol, acetylene and benzene. Berthelot then spent fifteen years attempting to lay the foundation of chemical mechanics by a study of the heat changes involved in chemical reactions. While all his principles have not been accepted, this work is one of the most important in the history of chemistry, both as regards detailed discoveries and broad generalizations. One of its incidental results was his study of explosives and the theory of explosion. Berthelot next turned his