The collections contain a set of documents related, to a large extent, to the scientific, administrative and financial activity of the International Institutes of Physics and Chemistry Solvay (IIPCS). There is abundant correspondence between the members of the administrative and scientific commissions composed by e.g. the minutes of the commissions, the programs of each council as well as the lists of participating members. A majority of the documents in the collection consist of correspondence maintained by the presidents and secretaries of each commission, with actors from the scientific world in physics and chemistry: there are both administrative and scientific letters as well as exchanges related to the activities of the IIPCS in the scientific world, in its relationship with other scientific organizations or other members of the international scientific scene in both physics and chemistry. The oldest coins date back to 1910, while the newest ones are produced at this very moment because the IIPCS still exist and this fund is still open. Most of the documents kept in the ULB Archives belong to the period 1910-2004. The fund is incomplete: missing answers to letters, and documents during significant periods [weeks or even months or years of holes in the archives]. In addition, most of the correspondence threads kept in the fund have gaps. There are multiple reasons explaining the gaps, but one of these reasons is that many letters are located in different countries, where the members of the international Committee came from. For this reason, the Solvay Science Project aims to connect the Solvay Archive with international partners to virtually reunite the whole corpus. This vast documentary collection testifies to the intense participation of the IIPCS and its actors in the intellectual life and scientific advances of their time in both physics and chemistry.
Sorting: Doubles and triples have been removed. For scientifically "less important" documents such as participation vouchers for a recreational activity, one or two documents were kept randomly, the list of participants being available and sufficient for the historical understanding of the event.
Increases: This fund is open and a regular increase is to be expected as long as the IIPCS exist.