The term has been used in natural philosophy and physics to explain certain phenomena as the result of invisible and practically weightless (Latin: imponderabilis) fluids.
[1][2] In an article published in 1868, English inventor and polymath Fleeming Jenkin described myriad hypotheses of physics that had been put forth involving imponderable fluids:[3] Leibniz mentions with great disapproval a certain Hartsoeker who supposed that atoms moved in an ambient fluid, though the idea is not unlike his own.
It is difficult to trace the origin of the hypothesis, but Galileo and Hobbes both speak of a subtle ether.
We even find half-a-dozen imponderable co-existent fluids regarded with favour,—one called heat, another electricity, another phlogiston, another light, and what not, with little hard atoms swimming about, each endowed with forces of repulsion and attraction of all sorts, as was thought desirable.
"[7] M. Martin Ziegler[8] patented a method of producing a "vital fluid" by combining nitrogen and carbon in a porous cell containing ammonia, immersed in a vessel tilled with molasses.