 Using an alcohol lamp , Wöhler heated alternating layers of beryllium chloride and potassium in a wired @-@ shut platinum crucible . The above reaction immediately took place and caused the crucible to become white hot . Upon cooling and washing the resulting gray @-@ black powder he saw that it was made of fine particles with a dark metallic luster . The highly reactive potassium had been produced by the electrolysis of its compounds , a process discovered 21 years before . The chemical method using potassium yielded only small grains of beryllium from which no ingot of metal could be cast or hammered . 
