(a) The discovery of the protons is credited to Ernest Rutherford, but some give the credit of the protons to Eugene Goldstein.

(b) Goldstein discovered the anode rays, he did an experiment with a discharge tube which had perforated cathode.

(c) He observed that when a high voltage is applied there are streams of negatively charged particles from cathode towards the anode but also rays traveling from anode to the cathode were present.

(d) He found out that the anode rays had positively charged particles or H ⁺, he did not name the particles.

(e) In 1911 Ernest Rutherford performed the gold foil experiment by bombarding fast moving alpha particles on the gold foil.

(f) He concluded that there must a positively charged mass at the center of the atom to neutralize the negative charge of the atom.

(g) He named the positively charged particle as the proton around which the electron revolves.

(h) He also postulated that the size of the nucleus is very small compared to the atom and all the mass of an atom is present in the nucleus.

By the discoveries of Rutherford, the proton was discovered.