I’ve noticed something strange - chemists can’t seem to agree on what to call the process of a gas becoming a solid without passing through the liquid phase. Several dictionaries I’ve consulted say that’s called sublimation in either direction, but I’ve run into many sources that use the phrase deposition, or even condensation to refer to this process, some of them chemistry text books.
So what’s the deal? None of the dictionaries I’ve got at hand list this usage for deposition or condensation. Are they just behind the times, or is this some kind of scientific “slang”? And how does the scientific community (whatever that may be) look upon the usage of deposition and condensation?
My little dic gives a meaning for “sublime” which supports the two-way meaning, as follows:
To undergo or cause to undergo this process [to change directly from a solid to a vapour or gas without first melting] followed by a reverse change directly from a vapour to a solid: to sublime iodine onto glass.
The original sense of sublime seems to include both the solid-gas and gas-solid phase transitions – it refers to the process of purification by sublimation:
c1386 CHAUCER Can. Yeom. T. Preamb. 51 The care and wo That we hadden in oure matires sublymyng. 1460-70 Bk. Quinte Essence 4 By contynuel ascendynge and descendynge, by the which it is sublymed to so myche hines of glorificacioun. Ibid. 8 Take Mercurie at is sublymed with vitriol, & comen salt, & sal armoniac .7. or .10. tymes sublymed.
Sublime meaning the solid-gas transition dates from 1622: MALYNES Anc. Law-Merch. 274 There remaineth a Paste…called the Almond Paste, which by a limbecke receiuing fire, causeth the Quickesiluer to subleme [sic].
The gas-solid transition sense is attested 60 years later: 1682 K. DIGBY Chym. Secr. 169 It will sublime with it in very red flowers.
I was initially told that the ‘opposite’ of sublimation is ‘resublimation’, but that turned out to be one of many errors in high-school science textbooks. In a practical sense, sublimation almost always involves both phase transitions occurring in close proximity (at least in chemistry), so the need for a distinct term for each may not have arisen. ‘Deposition’ makes sense, at least in industry when it’s used in manufacturing and not purification. ‘Condensation’ isn’t something I’d say – it’s far too easy to confuse it with the gas-liquid phase transition, and that’s the sort of thing academics love to get pedantic about.
Above quotations from the Oxford English Dictionary, 2nd edition.