Invisibility cloak

Some things in this world are invisible, even without a magic spell or invisibility cloak. 

Fluorine is the last of the cousins. Its fairies are very wilful [sic], harder to catch, and harder still to keep, it is supposed that they have very active feet and wings, and wear the invisible cloak, but they are such little rascals that no one is quite sure of ever having caught them, separate from everything else. 

DukeToday (2006), Theoretical Blueprint for Invisibility Cloak Reported. Available from http //today.duke.edu/2006/05/cloaking.html [last accessed August 2011]. 

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