煤焦油
Apart from the benefits of gas lighting and heating, the process for producing coal gas yielded a number of other substances which were subsequently successfully exploited. Among these were coke; ammonia; phenol (carbolic acid), a disinfectant and one of the components of bakelite, the first synthetic plastic invented in 1910; and coal tar, which contained a number of organic chemicals. Coal tar was subsequently used to produce the first synthetic dye, mauve, by William Henry Perkin in 1856 and in 1853 was found, by Charles Gerhardt to contain the chemical acetylsalicylic acid, now known as aspirin.