5 interesting facts

Five things you may not have known about the world.

• The blues guitarist Robert Johnson's real name was John Robertson.
• Mice have both male and female reproductive organs when they're born, their gender is decided after a few days as one set shrivels and eventually disappears. This is one of the features which makes them useful in scientific experiments as their DNA has traces of both gender and so negates a lot of gender-bias.
  
• Chlorine is only posionous when mixed with air. When pure it can be breathed without harm, although oxygen is still needed to prevent asphyxiation.
• The largest paid of shoes ever made was made had metre high 'shoelifts'. The diminuitive owner of the shoe factory in which they were made insisted were modelled exactly on his own brogues and forget to remove the 'lifts' when giving them to the designer.
• Since the arrival of the Saxons, the word 'England' has appeared on maps spelt with an A, E, I, O and U as the initial letter.