nitric acid; iron(III) cation in not given avoiding disproportionation of Hg2(SCN)2 into Hg and (Hg(SCN)4)(2-) by titration of Hg2(NO3)2 soln. with K2Hg(SCN)4 soln. in 0.6 n HNO3; quantitative reaction by use of Fe(3+) as indicator and avoiding adsorption by very slow titration with stirring;;
