--- In norse_course@yahoogroups.com, "Patti (Wilson)" <originalpatricia@...> wrote:

> You would be surprised how many the negatives that had 
> ú - in CV - show as ó - in the text that we have for an assignment
> There must be an explanation - in syntax for this.

There is an explanation, but it has more to do with phonology and fashion than syntax. CV and Zoega both list all such words under ú-. CV explains their choice by saying that at that time, most normalised editions had adopted the spelling ú [ http://lexicon.ff.cuni.cz/png/oi_cleasbyvigfusson/b0469.png ]. But normalised editions nowadays are more likely to use ó-, hence our trouble.

The entry I linked to there has a useful bit about the history of the different spellings. Old Icelandic had ó-, and this is the normal spelling in the oldest and most reliable manuscripts, whereas ú- was more common in Old Norwegian (with the exception of certain dialects). In the later Middle Ages though, Icelandic scribes came to use ú- more and more often, along with several other Norwegian spellings. They may have been tailoring their spelling to a Norwegian readership. But the Icelandic scribes went back to using ó- in the 15th century, and ó- remains the standard spelling in Modern Icelandic. There probably wasn't a switch back and forth in Icelandic pronunciation, just writing fashion.

As for the reason why there are two forms, the prefix was originally *un (as it still is in English and German). The 'n' disappeared according to the regular sound-change rules, as Proto-Norse evolved into Old Norse, and the resulting nasalised 'u' was lengthened to compensate. In fully stressed positions, this vowel normally became 'ó' (e.g. Proto-Norse *Þunraz > Old Norse Þórr). It seems to have been normal in the dialect that Old Icelandic decended from for the negative prefix to be stressed (like un- in German), so the normal form in Icelandic came to be ó-.

Proto-Norse *unskaþidat > (Old) Icelanic óskatt

But in some regions, speakers tended to put the stress on the root instead and left the prefix unstressed (like un- in Modern English). And since there was no raising of unstressed nasalised 'ú' to 'ó' (as can been seen from the u-mutation in Proto-Germanic *magunz > Proto-Norse *magû > Old Norse mögu, acc.sg. of 'mögr' "son, boy"), the Norwegian dialects that left the prefix unstressed ended up with ú-.

Proto-Norse *unskaþidat > Old Norse (Norwegian) úskatt