Is This Carbide Worth Saving ?

Not sure but a cool jar….

The jar is, IDK about the carbide. What do you use it for?

If the flat isn't rusted through it should be fine
Test a small amount
Do you have a miners lamp?

The jar is 1923-33

For Lanterns, in the old days for Generators at the Auto Garage

I used to have a Miners Lamp but don’t have it Anymore

You can test it in a small worthless jar and a container of water
Add enough stones to submerge the jar when it has the lid on it
Poke a pair of small holes in the lid and add 2 spoonfuls to the jar
Put the lid on and put it in the container of water
Many safety procedures should be taken when you try this

Time to go fishing where no one else goes.

Looks like has drawn moisture. Careful how you dispose of it as any that hasn't will form Acetylene and can be e4xplocive