BoatBanter.com - View Single Post - Potable Water

Mark Borgerson

In article . com,
says...
I give up. My Masters degree in Physics is of no value here. My
Bachelors degree in Math is of no value here. My 20 years with the
university (retired) means nothing. Someone with an opinion (however
false) instead of facts of physical science, seems to be more able to
swing the belief of the uninformed.

I will try to explain it again.

The vacuum will hold the column of water in the tube.

Dont believe it?
Test this statement, take a simple soda straw stick in in a glass of
water put your finger over the end and lift it out. The 8" column of
water stays in the straw because of the vacuum in the top of the
straw. Now remove your finger and the water drops out. So, it
doesn't TAKE a 32' column of water, but that is the tallest column of
water that will be suspended, a simple law of physics.

Thats why a lift pump like the old rocker handle pitcher pumps have to
be replaced with either submerged or Jet pumps in deeper wells. A
lesser column WILL work however. At the top is a vacuum. If its 32
feet, thats the greatest vacuum you can create. There is salt water
on one side and fresh water on the other. The salt water will boil
earlier because of the salt content.

Now test that statement.
Put a pot on the stove and then before it comes to a boil add salt.
Voila, it begins to boil.

BZZZZT!!! FALSE!!!

Salt water DOES NOT boil at a lower temperature than fresh water. It
boils at a higher temperature. When you add salt to heated water,
it appears to boil because the water is superheated near the bottom of
the pan and the salt crystals provide "nuclei" that start the boiling
process. You can easily verify this by starting with two pans
of water, one salty and one fresh and heating them to their respective
boiling points and measuring the temperature. More explicit
instructions, aimed at middle school students are at:

http://aquarius.nasa.gov/pdfs/prop_fresh_sea.pdf

snip

Mark Borgerson

SNIP