Improvements in the preparation of certain dyestuff intermediates
A 1918 thesis by John Wesley Birchard, held by the University of Illinois Urbana-Champaign, on improved preparation methods for dyestuff intermediates, written for chemists and students of dye manufacture. Its pictures are plain line diagrams of benzene-ring structures, reaction arrows with reagents such as COCl2, HNO3 and SnCl2, and azo and amine linkages, which a designer could borrow as clean schematic motifs for scientific or industrial graphics.
