A large number of halogenated benzenes can be visualized, especially when the halogen substituents are interspersed with methyl groups. Typically they have strong and characteristic infrared bands. When there is more than one halogen atom in a molecule of this class the vapor pressure is not high enough to yield a good spectrum in a short cell. An expansion of this chapter will require adoption of a technique of weighing out the sample and using heat to vaporize it into a long path cell. See SPECTRA, chapter S.