Canal rays were discovered by Eugen Goldstein in 1886 during experiments with gas discharge tubes.
- Goldstein used a perforated cathode (with holes/canals) in a discharge tube
- He observed luminous streams passing through the holes opposite to cathode rays traveling from anode through the cathode
- He named them Kanalstrahlen (canal rays) because they passed through the canals
- Wilhelm Wien (1898) and J.J. Thomson confirmed these were streams of positively charged particles (cations)
- Canal rays directly led to the discovery of the proton by Ernest Rutherford
Distinction: Cathode rays travel from cathode to anode (negative to positive); canal rays travel in the opposite direction.