Dew point Apparatus

[bigmack]

I posted a few years ago wondering if anyone new what this was .http://www.chemtalk.com.au/viewtopic.ph ... 579#p40291
A few replied that they had one but Liz said her one was labelled as Dew Point Apparatus.

After much head scratching I have figured out how to use it if anyone needs to know .

Dew Point Apperatus.jpg

Firstly there is a Thermometer that fits into the back of the lower mixing tank .(In mine , the original cork bung had disintegrated so I wrapped Teflon tape around a thermometer and wedged it in tight .)
You fill one tank with warm water ( above ambient temp )
You fill the second tank with Ice cubes and cold water and let it cool . (You will see condensation forming on the side of the Ice cold tank )
Place the apparatus so the spout is running into a sink.

Run some warm water through the lower tank until the thermometer reads a stable temp ...then turn off the water .
Next slowly run the cold water .
The temp will slowly begin to fall .
Observe the top and sides of the mixing tank .....suddenly condensation will form .It's hard to see but if you continue to wipe the top with a tissue , suddenly you see the condensation .
The temperature that the Condensation appears is the Dew Point .