Museo Galileo
Virtual Museum
Set of mercury friction tubes
    • Setting:
      Room XI
    • Maker:
    • Date:
      first half 18th cent.
    • Materials:
      wood, glass, mercury
    • Dimensions:
      box 560x100x55 mm
    • Inventory:
    • Set of mercury friction tubes (Inv. 3765)

Wood box painted blue with green silk lining inside, containing a set of six differently shaped glass tubes. There are two bulbs with straight stems, one thin tube, one curved tube with remains of a head painted at one end, and two tubes with a number of restrictions. They are all sealed at one end with sealing wax. The tubes contain a little mercury and were originally evacuated. They were used to demonstrate that the friction of the mercury against the glass of the tubes in a vacuum produced the electric glow. The aim was to show the resemblance between this phenomenon and the glow of phosphorus in the dark. The experiment was accordingly known as the "electrical phosphorus" experiment. The glow was observed in a barometer by Jean Picard in 1676, and was demonstrated to be electrical by Francis Hauksbee Senior in 1706. Provenance: Lorraine collections.