Xylene (dimethylbenzene) is a colorless, transparent, aromatic liquid. It is the product of two hydrogen atoms on the benzene ring being replaced by methyl atoms. Its boiling point is 137-140°C. Xylene is divided into three isomers: o-xylene, m-xylene, and p-xylene according to the positions of the two methyl atoms. In industry, xylene refers to a mixture of the above isomers and ethylbenzene. The grade is generally the superior grade and first grade of the Chemicalbook of 3°C and 5°C distillation range of purified water. It can be mixed with ethanol, chloroform or ether at will and is insoluble in water. It is widely used in organic solvents and synthetic medicines, coatings, resins, dyes, explosives and pesticides. Xylene is moderately toxic and also has certain carcinogenicity. Xylene pollution mainly comes from synthetic fibers, plastics, fuels, rubbers, additives of various coatings, various adhesives, waterproof materials, and can also come from the combustion gas of fuels and tobacco leaves.