The solid is den A crystalline solid, naphthalene has a strongly coal-tar odor. It is a white, volatile solid that is denser than water and insoluble in water. This material burns, but it may be difficult to ignite. It is very hot when molten. Avoid contact with skin. The material can also emit toxic vapors. Among its many uses are moth repellents, fumigants, lubricants, and making other chemicals.