(chemistry) A hydrate whose solid contains ten molecules of water of crystallization per molecule, or per unit cell.
Its maximum solubility in water is at 34 0; above that temperature it ceases to exist in the solution as a decahydrate, but changes to the anhydrous salt, the solubility of which decreases with rise of temperature.
Soc., 1909, 95, p. 1184) failed to obtain a decahydrate which had been previously described.
Common washing soda or soda-crystals is the decahydrate, Na2C03 IoH 2 O, which appears as large clear monoclinic crystals.
On exposure, it loses water and gives the monohydrate, Na2C03 H20, a white powder sold as "crystal carbonate"; this substance, which is also formed on heating the decahydrate to 34°, crystallizes in the rhombic system.
The pentahydrate is deposited between 79° C. and 56° C.; below this temperature the decahydrate or'ordinary borax,Na2B407.10H20, is deposited.