Molybdo-vanadoarsenates

A number of compounds have been described which are analogous to the molybdo-vanadophosphates described above, and which contain arsenic for the nuclear atom of the complex anion. In many cases these compounds approximate to the general formula , where x+y = 6; x and y are not necessarily whole numbers, because of the tendency shown by these heteropolyacid salts to form isomorphous mixtures of simple compounds. Ammonium, barium and thallium salts have been prepared.