io CHEMISTRY 



sulphuric acid for use in the production of explosives, 

 and the employment of chlorine as a military 

 asphyxiant, has been briefly indicated ; but the 

 relationship between chemical industry and national 

 prosperity extends much further. The manufacture 

 of ammonia and nitric acid has just been mentioned ; 

 in pre-war days the most important applications of 

 these substances, or their salts, were as artificial 

 manures. This country produces some 450,000 

 tons of ammonia per annum, chiefly from the 

 distillation of coal, and most of this is used as 

 manure; similarly, much of the British import of 

 Chili saltpetre, which has recently found a com- 

 petitor in the Scandinavian nitrate, went into the 

 soil. It has been indicated above that Germany 

 has been forced to produce ammonia and nitric 

 acid by new methods for war purposes and it may 

 be anticipated with some confidence that a shortage 

 in these heavy chemicals will be reflected in a light 

 German cereal and tuber harvest this year. 



During the past fifty years the German coal 

 tar colour industry has been developed to such per- 

 fection, upon a scientific foundation laid entirely 

 in this country, that the production of natural 

 dyestuffs has become insignificant. This is the 

 more striking in that the trade in natural dye- 

 stuffs, indigo, madder, logwood, etc. was largely 

 in British hands. Germany has taken from us one 

 of the earliest industries of these Islands; the 

 ancient Britons produced indigo for decorative 



