Simplify the following text for a Grade 8 native English-speaking person.
Original: The thallium is several times precipitated from the solution and to remove further impurities . At the end it is converted to thallium sulfate and the thallium is extraced by electrolysis on platinum or stainless steel plates .
Simplified: Then the thallium ( I ) sulfate is electrolyzed to make thallium metal .