In chemistry, affinity reactions were verbal or diagrammatic representations of attachment rearrangements between chemical species based on affinity preferences. Affinity reactions were prototypes for the modern “chemical reactions”. The stimulation or origin of verbal descriptions of affinity reactions and their diagrams stems from Query 31 of English physicist Isaac Newton’s 1718 edition of his Opticks, in which he verbally describes various gradients of “affinity” relationships between alchemical species. This statement later served the basis for the design of "affinity tables" and later the first affinity reactions diagrams made in the 1757 lectures of Scottish physician and chemist William Cullen. [1] Affinity reactions went by various names such as single elective affinity or double elective affinity, etc.

Single elective affinity reaction
The basic example is the "single elective affinity" reaction. In 1718, during a translation into French of Newton's Opticks, French physician and chemist Étienne Geoffroy made the world's first "affinity table" a sixteen-column, eight-row table, containing twenty-four reacting species, showing specifically what affinity reactions would occur between various combinations of reactants. Geoffroy's first law of affinity was that:

"Whenever two substances are united that have a disposition to combine and a third is added that has a greater affinity with one of them, these two will unite, and drive out the other."

To expound on this law, using data from the 1718 edition of Newton's Opticks (query 31), Geoffroy made a sixteen-column, eight-row, affinity containing twenty-four reacting species, showing specifically what affinity reactions would occur between various combinations of reactants. In 1757, using Geoffroy's table, Scottish physician and chemist William Cullen utilized bonding brackets "{" and affinity preference darts "→" to pictorially discuss affinity preferences. Shown below, for instance, using Geoffroy's first law, if chemical species A and B are attached in a weakly bonded chemical union, signified by the bonding bracket “{“, ordered such that if species C were introduced into the system, the greater affinity preference of A for C would cause A to displace B and to thus form a new union with C:

This equates to the following in modern terms:

AB + C → AC + B

Soon other chemist began to use Cullen's diagrams in publication. In 1775, Swedish chemist Torbern Bergman, in his textbook A Dissertation on Elective Attractions, made sixty-four affinity reaction diagrams. [2] In 1809, using Bergman's textbook and diagrams, of single and double elective affinity reactions, as a basis of universal chemical logic, German polymath Johann Goethe published his famed book Elective Affinities, the founding book of the science of human chemistry, in which he presented the view that people react according to the laws of affinity, just as do smaller chemical species. [3]

See also
● Affinity of reaction
● Elective affinity
● Chemical affinity
● Human elective affinity

References
1. (a) Crosland, M. P. (1959). “The use of diagrams as chemical ‘equations’ in the lecture notes of William Cullen and Joseph Black.” Annals of Science, Vol 15, Num 2, June.
(b) Thims, Libb. (2007). Human Chemistry (Volume Two), (pgs. 387, 392, 430, 534, 612, 655), (preview), (Google books). Morrisville, NC: LuLu.
2. Bergman, Torbern. (1775). A Dissertation on Elective Attractions. London: Frank Cass & Co.
3. Tantillo, Astrida O. (2001). Goethe's Elective Affinities and the Critics. New York: Camden House.