Admittedly there was no evidence that Rosy’s samples contained any divalent ions, and so we might be sticking our necks out.

In these salts X = NO2 and M = one atomic proportion of a monovalent metal, or the equivalent quantity of a divalent metal.

Group I.: the alkali metals Li, Na, K, Rb, Cs, and also Ag, monovalent; Cu, monovalent and divalent; Au, monovalent and trivalent.