Testing for common gases

Testing for hydrogen, oxygen and carbon dioxide.

http://lavenderpondnotes.tumblr.com/post/88615443871/testing-for-hydrogen-we-generated-hydrogen-by

http://lavenderpondnotes.tumblr.com/post/88574449096/catalysts-and-testing-for-oxygen-a-catalyst-is

http://lavenderpondnotes.tumblr.com/post/86243516181/lydia-observing-the-positive-test-for-the-presence