This book originated in a series of articles prepared for _The Independent_ in 1917-18 for the purpose of interesting the general reader in the recent achievements of industrial chemistry and providing supplementary reading for students of chemistry in colleges and high schools. I am indebted to Hamilton Holt, editor of _The Independent_, and to Karl V.S. Howland, its publisher, for stimulus and opportunity to undertake the writing of these pages and for the privilege of reprinting them in this form. In gathering the material for this volume I have received the kindly aid of so many companies and individuals that it is impossible to thank them all but I must at least mention as those to whom I am especially grateful for information, advice and criticism: Thomas H. Norton of the Department of Commerce; Dr. Bernhard C. Hesse; H.S. Bailey of the Department of Agriculture; Professor Julius Stieglitz of the University of Chicago; L.E. Edgar of the Du Pont de Nemours Company; Milton Whitney of the U.S. Bureau of Soils; Dr. H.N. McCoy; K.F. Kellerman of the Bureau of Plant Industry. E.E.S. LIST OF ILLUSTRATIONS The production of new and stronger forms of steel is one of the greatest triumphs of modern chemistry _Frontispiece_ FACING PAGE The hand grenades contain potential chemical energy capable of causing a vast amount of destruction when released 16 Women in a munition plant engaged in the manufacture of tri-nitro-toluol 17 A chemical reaction on a large scale 32 Burning air in a Birkeland-Eyde furnace at the DuPont plant 33 A battery of Birkeland-Eyde furnaces for the fixation of nitrogen at the DuPont plant 33 Fixing nitrogen by calcium carbide 40 A barrow full of potash salts extracted from six tons of green kelp by the government chemists 41 Nature's silent method of nitrogen fixation 41 In order to secure a new supply of potash salts the United States Government set up an experimental plant at Sutherland, California, for utilization of kelp 52 Overhead suction at the San Diego wharf pumping kelp from the barge to the digestion tanks 53 The kelp harvester gathering the seaweed from the Pacific Ocean 53 A battery of Koppers by-product coke-ovens at the plant of the Bethlehem Steel Company, Sparrows Point, Maryland 60 In these mixing vats at the Buffalo Works, aniline dyes are prepared 61 A paper mill in action 120