COAL-TAR 59 



comes directly from coal tar. If this is acted upon by 

 nitric acid, picric acid is formed, which is a dye, a drug, 

 and an explosive. Treat picric acid with chlorine and 

 we get chlorpicrin, one of the poison gases first used in 

 the late war. The mother substance of this group of 

 aromatic compounds is benzene, a colourless liquid. 

 Treated with nitric acid this becomes nitrobenzene, and 

 this reduced by hydrogen gives aniline, from which the 

 innumerable and variously coloured aniline dyes are 

 made. Acting on aniline dye with acetic acid, the acid 

 of vinegar, gives us acetanilid, a headache remedy, or, 

 rather, relief. Toluene, the next member of the series 

 to benzene, can be converted by similar treatment into 

 dyes and drugs, explosives and sedatives, perfumes and 

 poison gas. The benzene family is remarkably versatile. 

 What is made for one purpose often serves for another. 

 During the war the women munition workers in England 

 were found to be using trinitrotoluene for dyeing their 

 hair an auburn shade, and had to be warned against 

 the dangerous practice by an official of the Explosives 

 Department. 



When we were children and played the "game of 

 twenty questions" we always used to begin by asking 

 "Is it animal, mineral, or vegetable?" We thought by 

 that to corner the unknown object in one of the three 

 kingdoms of nature, for it did not occur to us that any 

 material thing could belong to more than one or lie 

 outside of all three. But there are no lines in nature. 

 What seem to us such are but merely the boundaries of 

 our own ignorance. The synthetic products of chemical 

 art, since they are built up from the primary elements 



