Full Idea
We cannot have a world where it is true both that salt exists (which requires Coulomb's Law to be true), and that it fails to dissolve in water (which requires Coulomb's Law to be false). So the dissolving is necessary even if the Law is contingent.
Gist of Idea
Salt necessarily dissolves in water, because of the law which makes the existence of salt possible
Source
Alexander Bird (Nature's Metaphysics [2007], 8.2)
Book Reference
Bird,Alexander: 'Nature's Metaphysics' [OUP 2007], p.178
A Reaction
Excellent. It is just like the bonfire on the Moon (imaginable through ignorance, but impossible). People who assert that the solubility of salt is contingent tend not to know much about chemistry.