Where is the rule about healing acid damage?

[Halaster Blackcloak]

Ok, either I'm getting senile or I haven't had enough sleep. I could swear there was a rule in 1E where acid damage could not be healed normally, but only by a regenerate spell or something along those lines. But I'll be damned if I can find it anywhere, in either the 1E or 2E DMG, PHB, etc.

Can anyone tell me where it is? I'm probably looking at it and glossing over it at this point. But I swear I remember something like this. Damage caused by acid does not heal over naturally, or with cure spells, only regenerate? Something like that?

[Varl]

2e DMG page 63 under types of grenade-like missiles.

[Halaster Blackcloak]

Thanks Varl! I believe I glossed over that sentence 20 times last night!

Hmmm. That's not the rule I remember though. I could swear that it was something along the lines of acid damage not healing naturally because of the extensive damage it did to tissues. In other words, the pure hp damage would heal, but not the scarring unless a regenerate spell was used.