Method of classification: The initial classification of the collections has been retained, as far as possible, unless there are major ranking inconsistencies. The content is organized into four organic collections:
Collection-1 [011Z/001] International Institute of Physics Solvay [1910-1963] contains correspondence, minutes, agendas, scientific articles, budgetary and administrative projects, accounting as well as the granting of grants from the Administrative Commission and the Scientific Commission of the International Institute of Physics Solvay. Added to this are preparatory correspondence, organizational correspondence, documents related to the organization of banquets and advice [thanks, invitations, organization, etc.], documents relating to the publication of scientific reports and the issuance of photographs as well as clippings for the first twelve physics councils from 1911 to 1962.
Collection-2 [011Z/002] International Institute of Chemistry Solvay [1910-1963] contains correspondence, minutes, agendas, scientific articles, budgetary and administrative projects, accounting as well as the granting of grants from the Administrative Commission and the Scientific Commission of the International Institute of Chemistry Solvay. Added to this are preparatory correspondence, organizational correspondence, documents related to the organization of banquets and advice [thanks, invitations, organization, etc.], documents relating to the publication of scientific reports and the photography program as well as clippings for the top ten chemistry councils from 1921 to 1962.
Collection-3 [011Z/003] International Institutes of Physics and Chemistry Solvay [1963 — 2004] contains correspondence, minutes, agendas, scientific articles, budgetary and administrative projects, accounting as well as the granting of grants and documents relating to the Solvay Chair created by the Administrative Commission and the Scientific Commission International Institutes of Physics and Chemistry Solvay. Added to this are preparatory correspondence, organizational correspondence, documents related to the organization of banquets and advice [thanks, invitations, organization, etc.], documents relating to the publication of scientific reports and the photography issue, as well as press clippings for physics councils and chemistry councils taking place since 1964. [Rating in progress and planned until 2004]
Collection-4 [011Z/004] Solvay Committee contains correspondence with the Faculty of Sciences of the Free University of Brussels on the subject of the Reform of Higher Technical Education. It also contains various files concerning donations offered by the Solvay committee, its participation in scientific travel projects or projects concerning Auguste Piccard, the University Foundation, the Rothschild Foundation or even a trip to the United States organized by Dustin.