Within the depth-psychology corpus, ‘Gas’ emerges not as a mere physical substance but as a psycho-historical threshold concept — the moment when the ancient pneuma, the spiritus silvestris of Paracelsus, was stripped of its animating soul and recast as controllable, measurable matter. Hillman’s Alchemical Psychology provides the richest treatment, tracing the word’s genealogy from van Helmont’s spiritus silvestris through the chemical revolution of Black, Priestley, Cavendish, and Lavoisier. For Hillman, the naming of ‘gas’ marks a crucial desouling of air: what had been spirit, breath, and elemental life became a substance subject to Boyle’s law, to compression and release at will. The psychologically charged resonance appears in the fairy-tale motif of the sealed bottle — ‘Let me out, let me out’ — where gas-as-spirit desires liberation from the alchemical vessel. Humphry Davy’s experiments with laughing gas further dramatize the ambivalence: the gaseous can transport consciousness into ecstasy or become instrument of political devastation, as in the artillery powder charges entangling both Priestley and Lavoisier with revolution. Frankl’s solitary use of the term marks its darkest register — the gas chamber as absolute negation of the pneumatic tradition. Across these voices, gas stands at the crossing of spirit and matter, poetry and technology, liberation and imprisonment.