Data for a number of metal salts show some dependence on the salt concentration.
The metal salt is applied in solution and allowed to dry for up to 30 minutes.
It is often stored in the form of alkali metal salts.
Like many metal salts the molecular structure depends upon the physical state of the substance.
Some metal salts and acids have also been used as astringents.
The magnetic properties of certain metal salts are useful in some cases.
We can't risk heavy metal salts, especially on a world where they must be plentiful.
A metal salt such as cobalt chloride will start to dissolve in the water.
The filter probably didn't take out all the dissolved metal salts in the water.
These reactions are more efficient in the presence of metal salts.