In more recent literature (post World War II period), the anion in (NH4)10(W12O41)·5H2O has been shown to be [H2W12O42]10−, containing two hydrogen atoms, keeping two hydrogen atoms inside the cage.
Before about 1930, there has been some dispute about the exact composition of the salt, and both (NH4)10W12O41 and (NH4)6W7O24 were proposed.