Walter's Octet

[eschiss1]

Apologies. That makes interesting sense. I should have looked at the list first (now I have), since they're listed separately from the Op.1. Hrm. Either Op.1 is D major, D minor, C minor, which also makes sense...  (since I have no compelling reason, as noted, to believe that Op.1 no.2 really is in F major...)

or he wrote 5 quartets.

I don't know...

[eschiss1]

Royal Library of the Netherlands does seem to agree that the quartets are in D major, C minor, F major , published by Tobias Haslinger's widow and son in 1844. They're not always right either, but ... hrm. (BSB Munich has, I think, the published score, and also is willing to digitize-on-demand, while Basel is willing to digitize the ms... just need to set up an account, it seems. Ponder, ponder, ponder...
The minuet of the D major quartet looks compact and pleasant (this is actually meant as a compliment. With a good contrasting trio.)

[eschiss1]

About the octet, this has probably already been said, but it may date back at least as early as 1843 though again maybe not published until as late as 1850 (though again, not 1863): the 18 February 1843 issue of ""Der" Adler: Allgemeine Welt- und National-Chronik ..., Volume 1; Volume 6" mentions a new octet by A. Walter, in manuscript , performed (or to be performed - my ability to read these things is horrible) privately at the home of Franz Glöggl on 20 February (p.172 of the issue, as scanned by Google Books).

[Mark Thomas]

There's no reason why the Octet couldn't be as early as 1843, he was writing for orchestra as early as 1841. Stylistically, it wouldn't be too advanced for the early 1840s, either, and many of his published works came out several years after they were written.