Search.
This ONLY even PARTIALLY works in a 'kinda-sorta' a little-bit-better-than-linear-but-not-really-log' way, when you're using them in a THREE-TERMINAL application... i.e. when one terminal is connected to ground, and the other two are input and output for example.
You CANNOT do this with a two-terminal 'variable resistance' application; it doesn't work. -This seems to be where people are most interested in it: making reverse-log pots (which are otherwise nigh-impossible to source) for mic preamp gain controls (a la SSL 9k) or parametric EQ sweep controls...
In these applications, it CANNOT work.
Do a search; a full explanation has been typed out several times before, and it's pretty long-winded, but the fundamental concept is simple... If you're looking for a 2-terminal application however, it doesn't work.... and that's all you need to know if you don't want to read further.
Keith