Re: Pink Plasma

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> 
> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Hollmike-at-aol-dot-com>
> 
> Without a gauge, it would be impossible to know.   To calculate it would
> require know the amount of air vs water vapor inside the jar.  If it were all
> water vapor(and assuming a perfect seal), it could be as low as 25mm Hg
inside,
> but that would likely implode the jar..lol...
> Mike

	I have used ordinary one-quart glass canning jars to vacuum jars, with
no implosions yet.  Always worried about that and was careful what I did
around them, but had good luck here.  Round jars with thick bottoms
should be safer yet.  Remember that as long as the pressure in the jar
is less than say 1/10 atmosphere, further evacuation is going to cause
only a very slight increase in stress.

	For what it's worth I use one-gallon jars for vacuum resevoirs on in
the forepump lines for diffusion pumps; the pressure there gets down to
a very few microns.  They are enclosed in large tin cans (we used to get
popcorn in them) and surrounded with plaster of paris for added safety. 
I have one of those I've used for 40 years without any problems.  First
got the idea from John Strong's wonderful book "Procedures in
Experimental Physics", which describes what guys were doing at Caltech
and other places in the late '30's.  In one of his illustrated figures
he shows an ordinary glass jug, surrounded by no protection at all,
sitting on the floor.  I would recommend this book to almost any home
experimenter; it's full of valuable information on an amazing variety of
things.  Lindsay sells a reprint for a very low price.

Ed