what did goldstein discover

Eugen Goldstein, a German physicist, is best known for discovering canal rays (also called anode rays) in gas discharge tubes in 1886, which were streams of positively charged particles traveling in the opposite direction to cathode rays. His work with these canal rays provided the first observation of what are now known as protons in hydrogen gas and helped lay the groundwork for later discoveries about the atomic nucleus and isotopes. He also made important contributions to the study of cathode rays, showing they travel perpendicular to the cathode and can cast sharp shadows, which supported the idea that they were streams of particles rather than just electromagnetic radiation.