<p style='text-align: justify;'>This is a piece of standard apparatus used by Rutherford in Manchester and then by G. Crowe, his assistant in Cambridge. It was used as a source of radioactive radon. The glass bulb at the bottom was used to store the radium salt, for example radium bromide, dissolved in weak hydrochloric acid. The radon gas was retrieved by opening the stopcock at the top and letting it pass into a Toepler mercury pump (see P972).</p>