The French use the word chateau for castle but it used to cover both: the Chateau-Gaillard, a fortress of the 12th century; and the manors dating from the 12th to the 18th century, which have no or little defensive capability.he French use the word chateau for castle but it used to cover both: the Chateau-Gaillard, a fortress of the 12th century; and the manors dating from the 12th to the 18th century, which have no or little defensive capability.
Hydrate, any compound containing water in the form of H2O molecules, usually, but not always, with a definite content of water by weight. The best-known hydrates are crystalline solids that lose their fundamental structures upon removal of the bound water.
The notation  hydrated compound ânH2O , where n is the number of water molecules per formula unit of the salt, is commonly used to show that a salt is hydrated. The n is usually a low integer, though it is possible for fractional values to occur. For example, in a monohydrate n is one, and in a hexahydrate n is 6.or example, ethanol, CH 3 âCH 2 âOH, is the product of the hydration reaction of ethene, CH 2 =CH 2, formed by the addition of H to one C and OH to the other C, and so can be considered as the hydrate of ethene.