Found this:
“Yhe addition of salt in coffee dampens bitterness without using other additives. Salt naturally brings out the sweetness of coffee and maintains pleasant aromas. If people are sensitive to bitterness, even in specialty coffee, adding salt is a good alternative to using milk and sugar.”
Never heard that before, but lots of references!
I have heard about add salt in the coffee due to the water of melted snow.
But it can be the bitterness softening.
If you drink a lot of (horrible) instant coffee, you'll know that they load it full of salt to enhance the flavour. I haven't had to drink instant coffee since I retired from the regular Army (I've had to drink it occasionally in the Reserves, but not much) because it pisses me off.
On a positive note, I just bought a new repro girder front end for my little 1949 BSA C11. By 1949 my model had a telescopic fork, but they look better with the girder front end that the earlier models came with, so I had to have it. It was advertised for $818 (plus tax, but free shipping, from India) "Or best offer" so I offered $707, and the seller came back with a counter offer of $730. (all $ AUD, so say around $500 USD) I grabbed it with both hands, the price had been lowered from over $1000 when I first looked at them a couple of years ago, so I'm happy that I've saved a little bit more.
