I thought it was about time we explored the music of Samuel de Lange (1840-1911), older bother of Daniël. Wikipedia has this:
His musical works include over 800 compositions, among which are 13 string quartets, many organ compositions, three cello concertos, two piano concertos, two violin concertos, one viola concerto, four piano sonatas, four violin sonatas, three cello sonatas, a clarinet sonata in c minor,[1] five piano trios, a piano quintet, a string quintet and hundreds of vocal works in a variety of settings.
https://en.wikipedia.org/wiki/Samuel_de_Lange#Compositions (https://en.wikipedia.org/wiki/Samuel_de_Lange#Compositions)
YouTube has his Viola Concerto:
https://www.youtube.com/watch?v=IB3USH9BmQA (https://www.youtube.com/watch?v=IB3USH9BmQA)
his Organ Sonata No.5:
https://www.youtube.com/watch?v=QadCmTEpZwQ (https://www.youtube.com/watch?v=QadCmTEpZwQ)
and his String Quartet No.4:
https://www.youtube.com/watch?v=rRgkOvcY1vY (https://www.youtube.com/watch?v=rRgkOvcY1vY)
IMSLP has this listing:
https://imslp.org/wiki/Category:Lange_Jr.,_Samuel_de (https://imslp.org/wiki/Category:Lange_Jr.,_Samuel_de)
So, has anyone any other information?
http://www.stichtingdelange.nl/ Problem for many forum members may be the exclusive Dutch tongue on the site mentioned.....
Here's the start (!) of the catalogue of his works:
http://www.stichtingdelange.nl/cms/?page_id=460 (http://www.stichtingdelange.nl/cms/?page_id=460)