HCIO₄ F.W.: 100.46 NFPA#: 3-0-1 Specific Gravity: 1.660 DOT: 1/8/I Descriptions: Trace metal grade. Low ppb metal impurities. Note: Results reported at time of bottling in glass. The levels of Al, B, Ca, K, Mg, Mn, Na, and Si will increase over time.