It is shown that there are exact solutions of the free Maxwell equations (FME) in vacuum allowing the existence of stable spherical formations of the free magnetic field and ring-like formations of the free electric field. It is detected that the form of these spheres and rings does not change with time in vacuum. It is shown that these convergent solutions are the result of the interference of some divergent solutions of the FME. One can surmise that these electromagnetic formations correspond to Kapitsaʼs hypothesis about interference origin and the structure of a fireball.