The graphitic oxide was prepared by stirring 100 g. of powdered flake graphite (Dixon's 635,325 mesh) and 50 g. of sodium nitrate into 2.3 liters of 66° Be technical sulfuric acid . The ingredients were mixed in a 15-liter battery jar that had been cooled to 0° in an ice-bath as a safety measure.
While maintaining vigorous agitation, 300 g. of potassium premangante was added to the suspension. The rate of addition was controlled carefully to prevent the temperature of the suspension from exceeding 20° .
The ice-bath was then removed and the temperature of the suspension broug3ht to 35±3° , where it was maintained for 30 minutes. As the reaction progressed, the mixture gradually thickened with a diminishing in effervescence. At the end of 20 minutes, the mixture became pasty with evolution of only a small amount of gas. The paste was brownish grey in color.
At the end of 30 minutes, 4.6 liters of water was slowly stirred into the paste, causing violent effervescence and an increase in temperature to 98°. The diluted suspension, now brown in color, was maintained at this temperature for 15 minutes. The suspension was then further diluted to approximately 14 liters with warm water and treated with 3 % hydrogen peroxide to reduce the residual permanganate and manganese dioxide to colorless soluble manganese sulfate. Upon treatment with peroxide, the suspension turned bright yellow. The suspension was filtered resulting in a yellow-brown filter cake. The filtered was conducted while the suspension was still warm to avoid precipitation of the slightly soluble salt of mellitic acid formed as a side reaction.