From: glhurst@onr.com (Gerald L. Hurst)
Newsgroups: alt.engr.explosives,rec.pyrotechnics
Subject: Re: Freedom of speech is freedom to change air pressure
Date: 18 Oct 1996 06:46:14 GMT

In article <32662C12.47711F21@fiscalinfo.com>, "Lloyd E. Sponenburgh"
<lloyds@fiscalinfo.com> says:

>An otherwise good post.  But for this.
>> bottom of the scale note the fizz in a glass of soda pop.  Have you
>> not felt the little stings on your hand or in your mouth as the
>> tiny bubbles break and produce minishocks?
>
>The sting is cause by the solution entering pores and interstices of
>your tongue and/or hand, and also (a little) by penetrating the surface
>by simple osmosis, THEN releasing the dissolved CO2 INSIDE the tissue --
>which causes a painful local expansion of the tissue.  Kind of like
>localized, surface 'bends'.  Tain't shock waves, Jerry.
>
>
>The NOISE you hear is tiny shock waves, though.
>
>>Jerry (ICO)
>
>LLoyd

Sorry Lloyd, but osmosis is way, way too slow to account for the sting and
you're not going to sell me the "enters the pores" story either.  

Allow me to point out that the pressure inside fizz bubblets is not 
negligible. The sparkly feel of carbonation also occurs with mechanically 
dispersed gases which have little solubility in water and thus cannot
osmose significantly better as a dispersion than they could otherwise do
as straight gases (which obviously do not cause a tingle).

Let me then go on and remind you of the mechanism of shock tubes in which
nothing more than the rupture of a thin membrane is required to initiate
a very hot shock front.  I might even remind you that the tensile strength
of water is of the order of 10,000 PSI, which means that a bubble wall
has the equivalent strength of a reasonably good plastic film of 
comparable thickness.  It's true that the bubble walls are not very thick
but then the bubbles are not very big either, and that means they can 
support respectable pressures before they rupture.  Now, that pressure 
also has another representation: the stretched skin of the droplet. 

My personal guess is that the tiny shocks are from the impact of 
microdroplets of liquid propelled from the collapsing lower bubble surface
of the water as the bubbles emerge and rupture at the top.  Think of
those suddenly topless little hemispheres as shaped charges being
propelled by the slingshot rubber of the concave lower surface trying
to minimize itself.  You can't really separate bubble pressure and
surface energy effects.  Take a look at the space above a fresh
Alkaseltzer (R) -- it is full of microscopic droplets which you can see
dancing at a considerable height above the glass. Those little suckers
must have a fair initial velocity given their small
mass-to-surface-area ratio and consequent high air resistance.

BTW, I have neglected above the chemical "feel" of straight CO2 gas in 
the throat and mouth which may be a function of mild acidity.  What I
am discussing is the sensation that also occurrs on exterior surface skin.

Hey Lloyd, if we could develop this osmosis thing a little, maybe we 
could breath through our skin and fish could dispense with gills.

Something tells me you read your osmosis information somewhere that you 
might be able to quote as a source.  It sounds just plausible enough to
sell to AOL.  Your turn, Lloyd :)

Jerry (Ico)

From: glhurst@onr.com (Gerald L. Hurst)
Newsgroups: alt.engr.explosives,rec.pyrotechnics
Subject: Re: Carbonation (was: Re: Freedom of speech ...)
Date: 18 Oct 1996 20:25:48 GMT

In article <548ljtINNk3u@HOBBES.NA.CS.YALE.EDU>, yarvin@cs.yale.edu
(Norman Yarvin) says:

>glhurst@onr.com (Gerald L. Hurst) writes:
>
> [much interesting information deleted]
>
>>My personal guess is that the tiny shocks are from the impact of 
>>microdroplets of liquid propelled from the collapsing lower bubble surface
>>of the water as the bubbles emerge and rupture at the top.
>
>Hmm, by this point in reading the above excellent article, I had already
>come up with a different hypothesis: that the shocks which are felt on
>the tongue are generated right next to the tongue.  This is accounted
>for by supposing that the tongue contains nucleation sites on which
>bubbles can form, and that it is the merging of two of these bubbles
>which produces the felt shock.
>
>It'd be a bit hard for a tiny shock at the surface to produce a
>stinging effect one centimeter below the surface.

You bet you'd get a sting from contact bubbles.  Look at the analogous
mechanism of a lined Munroe cavity.  If you stand the target off, the
lining forms a jet which is analogous to an expelled droplet in our
example.  If you use it as a contact charge, then the jet cannot form
but the lining is accelerated against the target and causes it to spall 
by shock. Years ago we called these Miznet-chardin charges (or some 
French spelling in the general neighborhood of "MIZ-NAY SHARDEEN") and 
they were said to used anti-tank mines.  Even without a lining you can 
see the focus and slap phenomena and their change with distance.

With carbonated water you feel strong tingling on contact with the
tongue and a lesser tingle on the upper lip and nose as the decelerated
droplets from the old inner surface of the bubblet strike the further
removed and also less sensitive skin.

I am not telling anyone that the above is fact - it is my speculation
and I would be very happy to learn of any experimental evidence pro
or con.  As Lloyd pointed out there is an undeniable component of 
sparkle in the chemistry between CO2 and the tongue.  I am suggesting 
that there is also a purely physical component to Sprudelwasser and 
that it is somewhat analogous to the Munroe phenomena we see with 
explosives.

Wen schon, denn schon. Wenn nicht, zum Teufel damit.


Jerry (Ico)

From: glhurst@onr.com (Gerald L. Hurst)
Newsgroups: alt.engr.explosives,rec.pyrotechnics
Subject: Re: Freedom of speech is freedom to change air pressure
Date: 18 Oct 1996 19:35:44 GMT

In article <326780D6.7EFA2CC2@fiscalinfo.com>, "Lloyd E. Sponenburgh"
<lloyds@fiscalinfo.com> says:

>BTW -- Pure CO2, taken in the mouth, doesn't just have a
>'characteristic' acid feel -- it actually feels HOT...  AND you get a
>little of the 'spark' sensation.    I know that's a pretty subjective
>statement.  But I know the character of dilute acids and bases, and CO2
>gas doesn't convey either of those 'tastes' to me.

That is partly because you are used to the mere sourness of aqueous
acids.  CO2 and other gases also give thermal effects as they dissolve
from the gaseous state. You are, however, right that CO2 gives a bit of
a tingly effect on inhalation.  That is why I emphasized the effect on
skin per se, which is unaffected by taste-related sensations or acidity
(in the short term, of course).  If you have ever gotten a mouthful or
noseful of other acid vapors (HCl) you may have noted a similar feeling 
on the tongue (heat, tingle) separate from the acidic (sour) aftertaste.

You know, when you drop an object into water, the water rushing in to fill
the resulting crater shoots a jet of water upwards much higher than the 
original height of the object (at reasonably low heights).  This 
phenomenon is probably analogous to bubble bursts except that some of the
driving force is probably head pressure rather than surface pressure . It
would be interesting to concoct an experiment to measure the initial 
velocity of the spray from carbonated water.  Then add a tad of foamless 
surfactant to see what effect lowered surface tension has on that 
velocity.

Jerry (Ico)