[Obituaries]

Abstract

IT is with great regret that we receive the news of the death of the distinguished French man of science, Daniel Berthelot. The son of Marcelin Berthelot, the centenary of whose birth is being celebrated in the present year, Daniel Berthelot showed much of the originality and width of outlook of his illustrious father. After periods of service at the Sorbonne and the Collège de France, he became professor of physics at the 1Ecole de Pharmacie, and it was in his laboratory at Meudon that he made most of those discoveries and researches in the fields of pyrometry, temperature scales, gas densities, and the chemical effects of ultra-violet light for which his name will be held in remembrance. The famous characteristic equation which he introduced has become second in importance only to that of Van der Waals, and is more accurate than the latter within its legitimate field of application. Daniel Berthelot laid the foundations of accurate gas thermometry and the physical methods of determining molecular and atomic weights which have closely rivalled, if not even excelled, the most accurate procedure of gravimetric analysis. In the field of chemistry his most notable discovery was probably the production of formaldehyde when a mixture of water vapour and carbon dioxide is exposed to ultra-violet light, and of formamide when carbonic oxide and ammonia are similarly irradiated. These syntheses lie at the foundations of biochemistry.