The hydrated acid crystallizes in prisms which effloresce in air, and are readily soluble in water.
Still further evaporation causes these crystals to effloresce and pass into the anhydrous salt.
A solution of the pure salt yields fine prisms of the composition Na2Sn03+10H20, which effloresce in the air.
By evaporating in vacuo the solution obtained by dissolving iron in hydrochloric acid, there results bluish, monoclinic crystals of FeCl24H20, which deliquesce, turning greenish, on exposure to air, and effloresce in a desiccator.