calcium hydroxide, Ca(OH)2, colorless crystal or white powder. It is prepared by reacting calcium oxide (lime) with water, a process called slaking, and is also known as hydrated lime or slaked lime. When heated above 580°C it dehydrates, forming the oxide. Like the oxide, it has many uses, e.g., in liming soil, in sugar refining, and in preparing other compounds. It is a strong base and is widely used as an inexpensive alkali, often as a suspension in water (milk of lime); it is used in leather tanning to remove hair from hides.