Apparently there were biweekly reports, that were grouped and published biannually on January and July, each one with a sequential tome number.
For example, both Marie Curie's Polonium paper and Marie Curie's Radium paper were published in the second half of 1898 and fell in tome 127.
Public domain publication list: archive.org/search?query=comptes+rendus+academie+des+sciences&sort=-date&and%5B%5D=collection%3A%22pub_comptes-rendus-hebdomadaires-academie-des-sciences%22 but some years are randomly missing like 1898?
OK from here you can find all of them more clearly: www.academie-sciences.fr/en/Transmettre-les-connaissances/comptes-rendus-de-l-academie-des-sciences-numerisees-sur-le-site-de-la-bibliotheque-nationale-de-france.html
TODO how to download a PDF from? I can't even turn the pages...