Calcium hydroxide
Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca(OH). It is a colorless crystal or white powder and is obtained when calcium oxide (called "lime" or "quicklime") is mixed, or slaked with water. It has many names including hydrated lime, caustic lime, builders' lime, slack lime, cal, or pickling lime. Calcium hydroxide is used in many applications, including food preparation, where it has been identified as E number E526. Limewater is the common name for a saturated solution of calcium hydroxide.
Cobalt(II) chloride
On crystallization from water, the compound forms several hydrates ·"n", for "n" = 1, 2, 6, and 9. Claims of the formation of tri- and tetrahydrates have not been confirmed. The dihydrate is purple and hexahydrate is pink. It is usually supplied as the hexahydrate CoCl·6HO, which is one of the most commonly used cobalt compounds in the lab.
Because of the ease of the hydration/dehydration reaction, and the resulting color change, cobalt chloride is used as an indicator for water in desiccants.