Potassium Nickel IV Paraperiodate -Hydrate

To a solution of 3 g. of potassium metaperiodate (0.013 mol) in 400 to 500 ml. of boiling water is added, with stirring, a solution of 2 g. of nickel(II) sulfate 7-hydrate (0.007 mol). The boiling solution is stirred vigorously and treated over a period of 25 to 30 minutes with 4 g. of 

Nickel is determined by the gravimetric dimethyl-glyoxime procedure after reduction of the compound with sulfur dioxide and hydrochloric acid. Iodine is determined as silver iodide after reduction with sulfur dioxide in sulfuric acid medium. Total active oxygen is calculated by measuring the quantity of iodine liberated from potassium iodide in acidic solution. Alkali metals are determined as sulfates in the filtrates from the nickel determinations. 

Sodium and potassium nickel (IV) paraperiodates are almost completely insoluble in cold water. They decom- 

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