Gases, vapors and the like

[John Cooper <jcooper@BUCKNELL.EDU>]

On Wed, 21 Jul 1999, Leigh Palmer wrote:

> A gas is incapable of condensing; that is why one distinguishes
> a vapor from a gas. Often the region of a simple phase diagram
> for temperatures greater than the critical temperature is called
> the "gas phase", but the boundary between this and the vapor
> phase below that temperature is evidently artificial.
   Well, actually I thought all real gases, He, formula weight 2 and
higher, condense at sufficiently high pressure and low temperature.
   Beyond the critical point, chemists and chemical engineers refer to the
phase as a fluid, without reference to condensation phenomena at
sufficiently lower temperatures; below the critical temperature/pressure
that fluid phase is called a gas in these circles.
   Isn't it clear words, particularly in a rich language like ours, carry
multiple meanings, which have to be interpreted in context.  That's why we
have dictionaries, although even they differ.  Mine happens to be quite
clear that 'gas' and 'vapor' can be distinguished because vapor connotes
suspended particles as in a fog.  But then we/I say *vapor* pressure to
mean something quite different from *gas* pressure.  Engineers talk about
'wet' and 'dry' steam.
   Rigid adherence to uniform, unitary uses of words, or symbology for
that matter, may simplify the local situation but is inconsistent with the
way language, and symbology, is used even within/among professional
disciplines as closely related as physics and chemistry or chemistry and
chemical engineering.  It's a little like _speaking_ as Romans when in
Rome, or _hearing_ for that matter.
   Jack Uretsky has remarked cogently on the need to find out what the
question is before expending too much time trying to answer it.  Instead
of trying to impose a Pax Physica on the language, why not take the time
to conjure what the other fella is trying to say instead of berating those
who don't say it quite the way we would have?  Poets will tell us it is
*differences* in the uses of language by various users that contributes to
the beauty of its expressiveness.
   One-word-one-meaning is something my beginning students yearn for.  But
that isn't the way language is used; I prefer Jack's observation that you
have to come at a question/concept from several different directions/
aspects before you can begin to grasp the whole: like the blind men
attempting to integrate their individual experiences of an elephant.  I
think of language as a multi-dimensional, non-orthogonal vector space on
which we try to impose and interpret experience.  Rotate the frame of
reference and the projection of experience on each unit vector will differ
somewhat.  Frames rotate and translate.
   Language is not the experience; it's only the representation of aspects
of experience.  Paring the fruit of experience to fit the confines of
narrow linguistic definitions may well lose the flavor that is
understanding.  Linguistic rigidity may well be a first step toward, but
is not the end-all of, understanding.

 John N. Cooper, Chemistry
 Bucknell University
 Lewisburg PA 17837-2005
 jcooper@bucknell.edu
 http://www.facstaff.bucknell.edu/jcooper
 VOX 570-577-3673    FAX 570-577-1739