A (1:0.125 (or 0.25):2:2 by moles) natural graphite mixt. was kept for 2 (or 3) days at room temp., washed with 3 M HCl, dried and oxidized electrochem. in 96% H2SO4 or 70%HClO4 by cyclic vottammetry (CV) at -0.15 - 1.225 V or -0.15 -1.1 V (with HClO4). X-rays showed n=6 (I-c = 2.63 nm) as the ZnCl2 intercalation stage. Anodic oxidn. of ZnCl2-GIC in H2SO4 or HClO4 gave biintercalates ZnCl2-H2SO4 (or HClO4)-GBC. Synthesis time was essential. With the (1:0.25:2:2) graphite-CrO3-ZnCl2-12 M HCl in 3 days, I the graphite matrix contained both CrO3 and ZnCl2.