Chemistry Magic 159 



buildings, paper, gasoline for our automobiles, and thousands 

 of other materials such as dyes, medicines, drugs, perfumes, 

 soaps, rubber, and explosives are all carbon compounds. 



The Super-super By-Product: Coal Tar 



For many years man has sought to take nature's products 

 coal, water, wood, cotton, petroleum apart and then put 

 them together again to effect a chemical synthesis. Nature her- 

 self is tops in the field of chemical synthesis. For instance, the 

 changing of mulberry leaves, by a worm, into silk and the 

 formation of sugar, vegetable oils, and cotton fibers from 

 water, air, and sunshine. 



When bituminous coal is heated in an enclosed vessel, it 

 gives off gases and leaves coke (used in steelmaking) as a 

 residue. Coal tar also is left in the tubes and containers. At 

 first, its appearance was considered a nuisance and chemists 

 were put to work to get rid of it. Coal tar is now the basis of 

 the great chemical industries of dyes, modern explosives, dis- 

 infectants, synthetic perfumes, drugs, and synthetic resins. 



The study of coal-tar derivatives progressed rapidly after 

 the eighteen-year-old William Perkin produced the first coal- 

 tar dye, mauve, in 1856. Till then the dyeing of all textiles had 

 been carried out with plant juices like madder or indigo and 

 with animal excretions like the ancient Tyrian purple, pro- 

 duced by a snail-like Mediterranean shellfish. In 1868 two 

 German chemists synthesized alizarin (turkey red), the col- 

 oring matter of the madder plant from anthracene, and soon 

 ruined France's madder industry. The synthesis of indigo and 

 Tyrian purple followed in later years. 



While work on the aniline colors continued, other chem- 

 ists established the make-up of the simpler active constituents 

 of medicinal herbs and made similar drugs from coal tars. 

 Among them were salicylic acid for treating rheumatism, 



