Note 20 — Chapter XVI · ZINC, CADMIUM, AND MERCURY

Mercuric nitrate, Hg(NO3)2,8H2O, crystallises from a concentrated solution of mercury in an excess of boiling nitric acid. Water decomposes this salt; at the ordinary temperature crystals of a basic salt of the composition Hg(NO3)2,HgO,2H2O are formed, and with an excess of water the insoluble yellow basic salt Hg(NO3)2,H2O,2HgO. These three salts correspond with the type of ortho-nitric acid, (H3NO4)2, in which mercury is substituted for 1, 2 and 3 times H2. As all these salts still contain water, it is possible that they correspond with the tetrahydrate = N2O5 + 4H2O = N2O(OH)8 if ortho-nitric acid = N2O5 + 3H2O = 2NO(OH)3.