Retention of lead during oxidative ashing of selected naturally occurring carbonaceous substances

The amount of lead retained in the ash of lead-bearing carbonaceous material is essentially independent of the method of ashing. Samples containing lead in the range of 0.00X to 0.X per cent were ashed by ignition in a high-oxygen atmosphere and were also wet-ashed. The lead in the ash was determined colorimetrically. Results were the same by both methods, but the time required is 3 to 10 times less for the dry-ashing method.