Flame tests. Digital composite showing flame tests for different elements, left to right: cobalt, sodium, lithium, copper, boron, strontium, potassium, calcium. Nichrome wire loop is dipped into a solution of the respective compound (CoCl2, NaCl, LiCl, CuSO4, Na2B4O7, SrCl2, KCl, CaCl2) and brought into the flame from a propane Bunsen burner. The color of the flame is determined by the element's emission spectrum which is characteristic to that element. Therefore, flame test can be used as an analytic procedure for identifying elements.