Hi! I've been watching this video http://ocw.mit.edu/courses/chemistr...l-science-fall-2008/video-lectures/lecture-2/ on the discovery of electrons , and I have some doubts about it. The lecturer explains the cathode ray experiment performed by J.J Thomson. This is what I understood. The cathode ray is produced between a cathode and an anode. The anode has slit through which the ray passes through. Then a difference of voltage is applied by two plates on the side of the tube and the ray is deflected and hits the detector.So Thomson concludes that the ray is composed of negative charged particles which are much smaller than the atom, the electrons. In the lecture, it is also said that something else hits the detector, another part of the beam and that is deflected in a much smaller angle and in the opposite direction,the positive charges. So,what is the cathode ray made of? It is suppose to be made of electrons, but according to the lecture there is also this positive charge that also gets deflected. This experiment proves the existence of the electron, but doesn´t it also proves the existence of the proton?. Why did Thomson conclude that the electrons are particles(plum) and the positive charge is a pudding.? Thanks!