How do bath salts work?

I'd bought a whole bunch of bottles of bath salts to send as work related gifts.

Since I do enjoy a nice scented bubble bath, I decided to take a bottle for myself.

It's a good brand apparantly, but I couldn't see what all the fuss was about.

It didn't relax me any more than a hot bath would, didn't really have much of a scent, and frankly, I missed my bubbles.

I'm willing to give it another shot, but what are the bath salts supposed to be doing?

Same question about epson salts.