Deliquesce
Deliquesce , intransitive verb
[Latin deliquescere to melt, dissolve; de- + liquescere to become fluid, melt, from liquere to be fluid. See Liquid.]
(Chemistry) To dissolve gradually and become liquid by attracting and absorbing moisture from the air, as certain salts, acids, and alkalies.
In very moist air crystals of strontites deliquesce.