I remember going to school in May and/or June (depending on the weather) with a little white pill wrapped in wax paper inside my lunch box - it sat next to my sandwich, snack and piece of fruit (usually an apple). My mom told us that we needed to take them in the summertime to replenish our salts from sweating.
I don't remember being a particular sweaty kid, nor were my brothers but we did as mother told us to. I never hear about salt pills now and don't even know if you can still buy them. Our food has changed an awful lot (and I mean awful) since I was a kid and now it seems 1/4 of the products being sold are "sodium reduced" - perhaps that's another reason why these pills slowly faded away.
I've asked around and it seems people of my mom's generation remember them (and some of their kids of course) but not many others - in fact many gave me the strangest looks like I asked them if they'd met an alien or something (which they probably have but just didn't know it).
I think we've also just rebranded this concept - by replenishing salts and electrolytes with drinks like Gatorade and such. Here's on article on salt pills.
Do you remember taking them?