The alkali dissolves greases to produce water soluble products. Polonium dissolves readily in dilute acids but is only slightly soluble in alkalis. It dissolves and rinses quickly in hot water. This carbonic acid gradually dissolves limestone thereby enlarging the fissures. It dissolves in concentrated sodium hydroxide. It is susceptible to weathering and dissolves slowly in most dilute acids. Some of the desired compound dissolves in the warm solvent. This irreversibly dissolves the starch granule in water. It also dissolves in hydrochloric acid, but only with oxygen present. In molten metals, it dissolves and forms metal carbides. Ytterbium dissolves slowly in water, but quickly in acids, liberating hydrogen gas. It dissolves well in water to give mildly acidic solutions. Gelatin readily dissolves in hot water and sets to a gel on cooling. Rohypnols comes as a pill that dissolves in liquids. However, in some cases, a certain mineral dissolves and does not precipitate again.