I stumbled across this short article the other day. The article states that ants that live away from oceans or other bodies of salt water will often prefer salt over sweets. It seems like an interesting idea, so I thought I'd try it.
I gave my Formica subsericea colony honey and a cotton ball soaked in salt water. At first, the honey and the salt both had only two ants drinking, but five-ten minutes later, the honey only had three or four ants, while the salt had about seven or eight. The ants drinking the salt water also seemed a lot more excited about their find than the ones drinking honey.
I also tried this with my Tetramorium immigrans colony, but I didn't get any conclusive results. This is likely due to the fact that they are a largely diurnal species, so there weren't really any workers out foraging. I'll update this when they're more active.
Just a fun little discovery I thought I'd share.