This material, obtained by oxidation of graphite, was first prepd by Brodie in 1859; Hummers, Offeman, J. Am. Chem. Soc. 80, 1339 (1958). Its composition is not well defined but usually given as C4O(OH): Aragon de la Cruz, Cowley, Nature 196, 468 (1962), Acta Crystallogr. 16, 531 (1963). Prepn and manufacture: Hummers, US 2798878 (1957 to National Lead); Hummers, Offeman, loc. cit.; Ruskin, US 2933381 and US 2944881 (both 1960 to Union Carbide). Crystal structure: Aragon de la Cruz, Cowley, loc. cit.