|Google definitions of "chemical" and "metaphor", to give a respective sense of the term "chemical metaphor", as in a figure of speech in which a word or phrase from chemistry is applied to an object or action, which may or may not be literally applicable, depending.|
In 1809, German polyintellect Johann Goethe published his physical chemistry based novella Elective Affinities, which, in his 4 Sep 1809 advertisement, he described as “chemische Gleichnisrede”, the German term “Gleichnisrede” translating, per Google auto-translate, as “parable”. (Ѻ) Authors, ever since, however, depending on one’s disposition, outlook, and stance on the book, variously referred to Goethe’s novella either as analogy, metaphor, or parable, among others, depending. German American studies scholar Susan Winnett, in 1993, e.g., translated Goethe’s advertisement as follows: 
“Thus he must have wanted to take an ethical case and to follow a chemical metaphor back to its intellectual origins, especially since there is ultimately only one nature everywhere, and even the realm of serene freedom of reason is ceaselessly permeated with the traces of dark, passionate necessity that are only extinguishable by a higher power and perhaps also not in this life.”
Others, likewise, have characterized Max Weber’s borrowing of Goethe’s human chemical theory as metaphor upon metaphor; the following being one example from Polish-born Australian philosopher Harry Redner (2013) (Ѻ): 
“Of course, this idea must not be taken literally—any more than Weber's use of the term ‘elective affinities,’ also a chemical metaphor borrowed from Goethe, can be interpreted in terms of chemical valence. Such metaphors work in so far as theyare illuminating and their meaning guided by how well they serve to make things comprehensible.”
In 1981, American philosopher Robert Solomon penned a chapter section entitled “Made for Each Other: the Metaphysical Model”, wherein he touches on Aristophanes’ split human model of love (see: soul mate), Gilbert and Sullivan (c.1896) inspired (supposedly), Melchior Lengyel filmed Ninotchka emotional love vs. physicochemical love debate scene, turned Cole Porter's 1955 electromagnetic-discussing song “It’s a chemical reaction, that’s all”, to state the following: 
“The metaphysical model is based not on the idea that love is a refuge from isolated individualism but, quite the opposite, on the idea that love is the realization of bonds that are already formed, even before one meets one’s ‘other half’. The ontology of loneliness treats individuals as atoms [see: human atom], bouncing around the universe alone looking for other atoms, occasionally forming more or less stable molecules [see: human molecule and dihumanide molecule]. But if we were to pursue the same chemical metaphor into the metaphysical model, it would more nearly resemble what physicists today call ‘field theory’. A magnetic field, for instance, retains all of its electromagnetic properties whether or not there is any material there to make them manifest. So too, an individual is already a network of human relationships and expectations and these exist whether or not one finds another individual whose radiated forces and properties are complementary. The old expression about love being a matter of ‘chemical attraction’, from Goethe to Gilbert and Sullivan, is, scientifically, a century out of date; ‘attraction’ is no longer a question of one atom affecting another but the product of two electromagnetic fields, each of which exists prior to and independently of any particular atoms within its range.”
In 2013, Norwegian sociologist Johan Galtung, began to be grouped with Libb Thims, as being one of the early “chemical metaphor” theorists, specifically for his 1977 “Chemical Structure and Social Structure: an Essay on Structuralism”. 
● Chemical analogy
● Chemical simile
● Chemical teleology
● Human chemical theory
1. Solomon, Robert C. (1981). Love: Emotion, Myth, & Metaphor (pgs. 24-25). Prometheus Books, 1990.
2. (a) Galtung, Johan. (1977). “Chemical Structure and Social Structure: an Essay on Structuralism”, in: Mathematical Approaches to International Relations. Publisher.
(b) Credibility of Psychosocial Analogues of Feynman Diagrams (part #6) – Kairos.LaetusInPraesens.org.
3. (a) Winnett, Susan. (1993). Terrible Sociability: the Text of Manners in Laclos, Goethe, and James (pg. 102). Stanford University Press.
(b) Susan Winnett (about) – Phil-fak.uni-Duesseldorf.de.
4. Redner, Harry. (2013). Beyond Civilization: Society, Culture, and the Individual in the Age of Globalization (pg. #). Transactions Publishers.