Further loss of hydrogen gives "fused" aromatic hydrocarbons, such as naphthalene, anthracene, phenanthrene, and pyrene. Commercially used creosote is often treated to extract the carbolic acid, naphthalene, or anthracene content. Examples are naphthalene, anthracene, and phenanthrene. Or the formation of the pyrene "dibenzo-(a.1)-pyrene" from the anthracene "1-phenylbenz(a)anthracene" (66% yield). Other blackbody payloads include ammonium perchlorate/anthracene/magnesium and hydroxyl-terminated polybutadiene (HTPB) binder. This example utilizes poly(aryl ether) dendrons attached to a core aryl ether with [anthracene] attached. The name 'phenanthrene' is a composite of phenyl and anthracene. It contains among other things anthracene and phenol. These hydrogen donors undergo dehydrogenation to, respectively, carbon dioxide, acetone, and anthracene. Other combinations include ammonium perchlorate/anthracene/magnesium, or can be based on red phosphorus. Another option is to use sublimed magnesium or magnesium anthracene. A variety of anthracene derivatives find specialized uses. Other authors consider PAHs to start with the tricyclic species phenanthrene and anthracene. It is a colourless solid that is chemically somewhat similar to anthracene. Coal tar, which contains around 1.5% anthracene, remains a major source of this material.