A quantity of sample is weighed, placed in a crucible, and subjected to destructive distillation. During a fixed period of severe heating, the residue undergoes cracking and coking reactions . At the termination of the heating period, the crucible containing the carbonaceous residue is cooled in a desiccator and weighed. The residue remaining is calculated as a percentage of the original sample, and reported as Conradson carbon residue.