Chemie der organischen Farbstoffe
Chemie der organischen Farbstoffe is a German chemistry textbook on organic dyes by Rudolf Nietzki, published in Berlin by J. Springer in 1889 and held by the Royal College of Physicians in Edinburgh. Its pictures are structural formulas drawn as hexagon ring diagrams with substituent groups like NH2, CH3 and N linkages, which a designer could use as schematic line motifs of molecular geometry.
