Early examples of paper chromatography from German chemist Friedlieb Ferdinand Runge, who is considered to be the originator of the analytic technique. Runge investigated the color reactions of various chemical substances such as ammonia and iron or copper oxide. The results include these 22 smaller chromatograms mounted on the title page surrounding the title, and 60 larger chromatograms mounted on 31 leaves. The chromatograms consist of concentric circles of color produced by applying a liquid chemical compound to filter paper.