1 in E major, WoO, was one of the composer's earliest compositions for piano, violin, viola and cello.
[1][2] Instead of publishing the work, Saint-Saëns donated the manuscript, with others, to the library of the Conservatoire de Paris.
The work was finally published in 1992, by the Éditions Musicales du Marais.
[1] Silvertrust speculated in his article that it was because in the 1850s chamber music was hard to publish in France due to the interest in operas and that by the 1870s the work, which shows signs that the composer was inspired by Beethoven, Schubert and Schumann, was too German sounding to publish in France following the Franco-Prussian War.
[2] It is also possible that Saint-Saëns was reluctant to present the work to a Parisian audience that was, at the time, sceptical of music by contemporary French composers.