|A depiction of William Gilbert's 1663 "electric machine", a type of electrostatic generator, made of metallic sulfur globe, that, when spun, produced a charge, or something along these lines.|
In 1550, Gerolamo Cardano, in his On the Subtlety of Things, was the first, supposedly, to differentiate between the attraction of amber and the attraction of lodestone.  The following is how he viewed attraction in amber:
“Amber has a fatty and glutinous humor which, being emitted, the dry object desiring to absorb it is moved toward the source, that is the amber. For every dry thing, as soon as it begins to absorb moisture, is moved toward the moist source, like fire to its pasture; and since the amber is strongly rubbed, it draws the more because of its heat.”— Gerolamo Cardano (1550), On the Subtlety of Things (Volume 5) 
In 1600, William Gilbert, in his On Magnets, employed Cardano's “fatty and glutinous humor” theory the basis or origin of his ab humore effluvia or “electric effluvia”.  Gilbert Latin word "electrum", based on the Greek name "elektron" for amber, and for substances that behaved like amber he coined the term "electrica" which translates as electrics. 
In 1629, Niccolo Cabeo, in his Magnetic Philosophy, a book that attempted to refute the theories of William Gilbert (1600), from the Aristotelian view, made an important observation of electrical repulsion, reporting his observations that an electrically charged body can attract non-electrified objects, also that two charged objects repelled each other. 
In 1646, Thomas Browne, in his 1646 Pseudodoxia Epidemica, became the first English author to use the term "electricity". 
In 1663, Otto Guericke, in an effort to disprove William Gilbert's magnetic earth theory of gravity, invented the first electrostatic generator, a type of metallic globe or sulfur globe, that could be spun to produce charge. 
In 1675, Robert Boyle, in his “Mechanical Production of Electricity”, was freely using the term in respect, supposedly, to the earlier experimental demonstrations of electricity done by William Gilbert. (Ѻ)
In 1705, Francis Hauksbee, inspired by Jean Picard (Ѻ), who discovered that if he shook a mercury-containing barometer, it would produce a glow (Ѻ), placed mercury inside of a Guericke generator, which he built, shown below, which he then evacuated, with a vacuum pump, to make a mild vacuum inside, then rubbed the glass ball to build up a charge, and observed that a glow was visible when he placed his hand on the outside of the globe.
In 1729, Stephen Gray built an elongated Hauksbee generator, 3-feet long by 1.2-inch in diameter, and found that cork stuck in the end would alternately attract and repel a feather; after which he then began to test to see if he could conduct electricity through various things, such a silk cords. In later experiments with Granville Wheler, he was able to conduct electricity through up to many hundreds of feet.
In human chemical terms, writers often use the metaphor of a feeling of “electricity” between people, particularly when falling in love, or in reference to a state of excitement.  In music chemistry, for instance, the chorus to the popular 2007 song “Chemistry”, by Swedish pop-singer Velvet, is:
I feel the chemistry
Between you and me
when you're touching me
I feel the chemistry
feel the biogravity
I want you touching me
I feel you touching me
In positive psychology, the state of absorbed mental involvement called “flow”, for instance, was conceived in the 1970s by Croatian-born American psychologist Mihály Csíkszentmihályi and named as such due interviews of 173 subjects where people often described their 'flow' experiences using the metaphor of a current carrying them along. 
The metaphor of electricity between reacting human molecules is a difficult subject but may possibly be interpreted according to heightened or optimal states of neuro-electricity/neurotransmitter flow, thus instilling the sense of being alive. 
1. Daintith, John. (2005). Oxford Dictionary of Physics. New York: Oxford University Press.
2. (a) Brown, Thomas. (1646). Pseudodoxia Epidemica – or Enquiries into Very many Received Tenets and commonly presumed Truths. London.
(b) Kirby, R.S., Withington, S. Darling, A. B. and Kilgour, F.G. (1956). Engineering in History (pg. 329). New York: Dover.
3. Electricity (definition) – Merriam-Webster Collegiate Dictionary, 2000, CD-ROM.
4. Csíkszentmihályi, Mihály (1975). Beyond Boredom and Anxiety. San Francisco, CA: Jossey-Bass.
5. (a) Thims, Libb. (2007). Human Chemistry (Volume One), (preview). Morrisville, NC: LuLu.
(b) Thims, Libb. (2007). Human Chemistry (Volume Two), (preview). Morrisville, NC: LuLu.
6. Kirby, Richard. (1956). Engineering in History (co-authors: Sidney Withington, Arthur Darling, Frederick Kilgour) (pg. 329). Courier, 1990.
7. *********, Yamamoto. (2017). Pull of History: the Human Understanding of Magnetism and Gravity Through the Ages (pg. 480). World Scientific.
8. Benjamin, Park. (1898). History of Electricity: the Intellectual Rise in Electricity (§:Otto Guericke, pgs. 388-). John Wiley & Sons.
● Priestley, Joseph. (1767). The History and Present State of Electricity, with Original Experiments. Publisher.
● Electricity – Wikipedia.