Christel,
The lid is rusting because of its reaction with the nitric acid. As
long as you don’t splash the liquid around and into your eyes, there
is little or no danger in piercing the lid further, creating a hole
large enough to pour the (now probably very weak) acid out. You can
use a plastic bucket of cold water, into which you have dissolved
four tablespoons of baking soda; simply pour the contents of the jar
into the bucket, while stirring the liquid into the bucket.
In all likelihodd, the acid has probably long since broken down and
does not present an extreme hazard.
If you are that concerned about this material, why not soak an old
towel in the solution you made for the bucket, invert the jar on the
towel and the jar’s contents will seep into the towel, then you can
simply hang it to dry then discard it.
An open jar of nitric, even weak nitric, will corrode everything
ferrous within many feet of the source. Never store any acid or
alkali in a container with a metal lid.
Incidentally, once neutralized or even strongly diluted with water,
the nitric will cause no harm to the environment as it breaks down
into simply Nitrogen and Oxygen.
Again, for safety’s sake DO NOT add water to this container.
Wayne