A solution of the pure salt yields fine prisms of the composition Na2Sn03+10H20, which effloresce in the air.
The hydrated acid crystallizes in prisms which effloresce in air, and are readily soluble in water.
At ordinary temperatures it crystallizes from aqueous solutions in large colourless monoclinic prisms, which effloresce in dry air, and at 35° C. melt in their water of crystallization.
Still further evaporation causes these crystals to effloresce and pass into the anhydrous salt.
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.