Many everyday sayings have their origin in some scientific development or process.  For example, when you dub someone as ‘loving the limelight’ you infer that they like to be the centre of attention.  This phrase has its origin in an era when theatre stages were illuminated by heating calcium oxide, commonly known as lime.  Lime has a very high melting point.  When heated it glows, giving off bright white light.  When focused in a spotlight, it puts the actor in the ‘limelight.’

When you say someone passes the ‘acid test,’ meaning they’re people of integrity, you are using a phrase from the Gold Rush days.  Miners used to test nuggets with acid.  Gold is unique in its chemical stability and won’t react with strong acids.  If a nugget didn’t show any reaction when nitric acid was added it was judged genuine.  It passed the ‘acid test.’

Another saying which has its origins in chemistry is the phrase ‘as mad as a hatter.’  English hat makers once used mercury compounds to treat the felt used in shaping fashionable hats.  These compounds could be absorbed through the skin and seriously affect the nervous system.  Workers in the hat industry frequently showed tremors and behaviour changes which made them appear to be going crazy.

So next time you use a common saying, you may be capturing a moment in the history of science.