[engineeringguy]

Hello, I am president of the chemistry club at my school and I wanted to do the barking dog reaction. I need nitrous oxide and a way I can dispense it into a tube. Where would you buy such a chemical? Preferably from the cheapest possible source.

[Dan]

Something like this perhaps: https://en.wikipedia.org/wiki/Whipped-cream_charger

[jasongnome]

You could try making it yourself. The main method is to GENTLY heat small amounts of ammonium nitrate and collect the gas over water.

NH₃NO₂  2H₂O + N₂O

There's a diagram here (the water does need to be hot, but you don't need metal to hold the hose in place, your school lab should have ceramic "beehives", one of those is fine):

http://chemistry.about.com/od/makechemicalsyourself/ss/How-To-Make-Nitrous-Oxide-Or-Laughing-Gas.htm

SAFETY: with gentle heating the above reaction happens, however, if it gets too hot, it can decompose explosively. This method is commonly done in schools and was invented by Joseph Priestley, so it been around for a LONG time. It's safe as long as you take normal precautions, you should fill out a safety assessment first, and check with a qualified teacher before you do it.