This test method covers the determination of the coke residue (fixed carbon) of creosote, coal tar, and creosote-coal tar solutions. As coal tars vary in their coke residue values, the method is therefore not a quantitative index of the percentage of coal tar in creosote-coal tar solutions. However, by specifying maximum amounts of coke residue as done in AWPA Standards P2 and P12, the method does serve to limit the amount of coal tar in such solutions; and by specifying a minimum as in Standard P12 it ensures the presence of some coal tar. Formerly the test was also used as a check on the cleanliness of AWPA P1 creosote (absence of coal tar). Test Method D38 covers the sampling of wood preservatives prior to testing.This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See Section 6 for specific precautionary statements.