|In affinity chemistry, Bergman’s chemical signs explained is an appendix table to Swedish chemist Torbern Bergman's 1775 physical chemistry textbook A Dissertation on Elective Attractions, explaining the various chemical symbols and species found in his affinity table (see: Bergman's affinity table) and affinity reaction diagrams (see: Bergman's reaction diagrams). 
Bergman's table was the largest affinity table ever made. The table formed the basis of logic to the German polymath Johann Goethe’s 1809 human affinity table. In the decades to follow the publication of Bergman’s table, it became apparent that reactions were temperature dependent and that one table would have to be made for each degree on the temperature scale. This impediment eventually gave way to the construction of free energy tables, after it was shown in German physicist Hermann Helmholtz’s 1882 treatise The Thermodynamics of Chemical Processes, that the measure of affinity is equal to the negative of the free energy change for the given reaction or set of reactions in a system.
1. Bergman, Torbern. (1775). A Dissertation on Elective Attractions. London: Frank Cass & Co.