The resulting white product is termed calcium oxide lime, burnt lime, quicklime, cob lime, or caustic lime.
It was also necessary to give the fine charcoal a thin coating of calcium oxide by soaking it in lime-water, for the temperature was so high that unless it was thus protected it was gradually converted into graphite, losing its insulating power and diffusing the current through the lining and walls of the furnace.
Only so much lime is used that an acid manganite is formed corresponding to one molecule of calcium oxide to two of manganous oxide.
On cooling this calcium oxide will take up water to form calcium hydroxide.
Heating limestone to a high temperature in a limekiln produces calcium oxide (quicklime, a strong alkali ).