there are anhydrous double nitrates such as cerb(no) and cek(no). the potassium salt, cek(no) can be made by using the water solution of potassium nitrate and cerous nitrate in 3:2 molar ratio, evaporated at 40 °c. the crystals are colourless cubic from space group "p"432. its formula weight is 955.6. three formulas exist in each unit cell which at 20 °c, has a volume of 2514.1 å and cell side of a=13.597 å. the density is 2.525 g/cm. in this compound each cerium atoms is surrounded by twelve oxygen atoms from six nitrate groups. three of the nitrates form a bridge in each of three dimensions. these bridges form three spirals each at 90° to each other along the crystal axes.