The pictured threaded fitting, with the big nut-thing, is part of my bathtub water supply. Probably 1950ish. It seems to connect a copper pipe with the brass fitting. It is leaking.
First, what is that fitting called?
Second, what is the best packing for such a fitting? It seemed to have had teflon tape and some sort of white sealer. From the chewed-up nut and the remains of past sealers...it probably has been a problem for previous owners.