Re: Vapor?

["John S. Denker" <jsd@MONMOUTH.COM>]

Tina Fanetti wrote:
> See, I always thought vapor and gas were different.
> I thought that a vapor was kinda liquidy and you could
> see it, like steam in a bathroom.

The word is not used that way by experts.

Normally water vapor refers to gaseous H2O, which is
invisible.  The visible steam in a bathroom is a cloud,
a fog, an aerosol, that is, a colloidal suspension of
tiny liquid droplets suspended in gaseous air (along
with a small amount of gaseous H2O).

It's not worth fussing over whether the technical
definition agrees with the nontechnical definition.
(By way of analogy, think about the nontechnical use
of the word "elastic" as in "elastic waistband" --
having precious little connection to the technical
use.)


>  Also that it had an odor to it.

That's not a good criterion, either.
Methyl mercaptan !!definitely!! has an odor:
detection threshold circa 2 parts per billion.
And it's a gas: boiling point 5.9 C
  http://physchem.ox.ac.uk/MSDS/ME/methyl_mercaptan.html


> A gas was something that followed the ideal gas law,

It doesn't have to be ideal.

> but it filled up the space it was in and kinda floated.

Why say "but"???

One of the salient properties of a liquid or solid is
that it _doesn't_ fill up the container it's in.

BTW a cloud / fog / aerosol / colloid will not settle
to the bottom of the container.  Anything that does
tend to settle out would better be called a mist.

==========================

pojhome wrote:
> If my students were as well versed in English grammar as ....
>  I too could use words such as "salient".

Maybe I'm naive, but I would expect the vast majority of
students to know what "salient" means.  It might not be
in their speaking vocabulary, but it ought to be in their
reading vocabulary.  Or they could figure it out from
context. Or they could look it up.  Or they could ask.
It's not my style to talk down to students.

Evidence that the word isn't particularly obscure:

I get 305,000 hits from
  http://www.google.com/search?q=salient

compared to 956,000 hits from something utterly prosaic, such as
  http://www.google.com/search?q=shiny

Last night on the radio I heard the word used by a
baseball player who could barely string together three
grammatical sentences in a row.