The discovery of the positive charge of the atom is not attributed to a single scientist, but rather a series of experiments and theories by several physicists. Here's a breakdown:

* J.J. Thomson (1897): He discovered the electron, a negatively charged particle within the atom. This led to the plum pudding model, which proposed that the atom was a sphere of positive charge with electrons embedded within it.

* Ernest Rutherford (1911): His famous gold foil experiment showed that most alpha particles passed straight through a thin gold foil, but some were deflected at large angles. This led to the nuclear model, where the positive charge was concentrated in a tiny nucleus at the center of the atom, with electrons orbiting around it.

So, while Thomson's work led to the initial understanding of a positive charge within the atom, it was Rutherford who ultimately revealed the structure of the atom and the location of its positive charge in the nucleus.