I think I read that there is a special bond between DMT and fumaric acid that happens to work exceptionally well.
I've heard about ergolines, the tartrate salt protects the two positions in the structure that could otherwise oxidize.
Taken from the
wiki:
Quote:DMT fumarate is more water soluble, more stable, has a longer shelf life, is much easier to crystallize, has a higher melting point, is less waxy, and easier to form into a powder than freebase DMT.