Preparation mercuric thiocyanate
In a well ventilated place or outside (there is a large amount of oxides of nitrogen) pour 30 g of mercury and 60 ml of concentrated nitric acid. After a stormy reaction and dissolution of mercury solution briefly boil (to escape the remaining oxides of nitrogen). Add a few drops of ferric salt (light precipitation). Then, prepare a solution of 30 g KSCN (alternatively another rhodanides). This solution then under cooling and stirring was metered into a solution of mercuric nitrate, so that there is no permanent red color. Resulting precipitate was collected and dry air.