Chemists have not seen much of their discourse become part of popular culture, but the symbol for water is a notable exception. In advertising speak, H2O has a high recognition factor. It has been adopted and adapted for a plethora of cool brand names, a few geeky jokes and a successful Australian TV show and spin-off movie.
The symbol is a very neat way of summarising what we know about the composition of pure water. In each and every molecule of this ubiquitous substance, two hydrogen atoms are bound to one oxygen atom. Amazing stuff: we know from experiment that two invisible gases react to give this vital liquid; again from experiment, we know that two volumes of hydrogen react with one of oxygen; and we know, based on a wealth of careful experimentation and robustly debated theory, that this ratio is embodied in tiny invisible molecules made up of even smaller atoms.
What does this have to do with today’s Powerhouse Collection object, a limelight burner? Its two inlet pipes are designed to funnel hydrogen and oxygen gases towards the pointy end, where their reaction generates water and heat. The flame is directed towards the vertical spike, which is designed to hold a ball of quicklime (calcium oxide). Water reacts with quicklime, producing even more heat and a very bright light.
The use of limelight burners as theatre spotlights led to our saying ‘to be in the limelight’. This burner is one of many objects that will star in Science Underground, curator-led tours of our basement store during Ultimo Science Festival, a feast of activities on offer from 16-28 August 2011.