Tungsto-vanadoarsenates

These are comparable to the molybdo-vanadoarsenates, and can be represented generally,



where x+y = 6, although x and y are not necessarily whole numbers. Canneri found a definite relation to exist between the composition of the salt obtained and that of the solution from which it separates, from which it is inferred that a condition of equilibrium exists between various salts in solution or between their ions; this equilibrium for fixed concentrations is remarkably sensitive to changes in temperature or acidity. Among other salts three series of ammonium salts have been obtained which approach to the following formulae:

; ; .

Barium and thallium salts have also been described, and some of the free acids have been isolated.

Several ammonium salts have been prepared, which are most probably isomorphous mixtures of arsenates and phosphates.

Vanado-tungstomolybdoarsenophosphates have been described; these are also isomorphous mixtures of simple compounds.