The white precipitate consists of lead sulphate.
Thus, a mixture of lead sulphate (45%) and oxide (44%) with some sulphide (8%), zinc and carbonaceous matter, is agglomerated by a heap-roast and then smelted in a slag-eye furnace with grey slag from the ore-hearth.
The most accurate method for the determination of lead in ores is the gravimetric method, in which it is weighed as lead sulphate after the various impurities have been separated.
It is standardized by dissolving a weighed amount of lead sulphate in ammonium acetate and proceeding as described above.
] Hydrogen peroxide behaves very frequently as a powerful oxidizing agent; thus lead sulphide is converted into lead sulphate in presence of a dilute aqueous solution of the peroxide, the hydroxides of the alkaline earth metals are converted into peroxides of the type MO 2.8H 2 0, titanium dioxide is converted into the trioxide, iodine is liberated from potassium iodide, and nitriles (in alkaline solution) are converted into acid-amides (B.