To the Possibility of Measurements of Orthopositronium Annihilation Amplitudes for QED Testing

In connection with previously revealed disagreement of theoretically calculated and measured orthopositronium decay rate in vacuum we suggest the experiment to clarify which of the positronium annihilation amplitudes R$\text{}_{m}$,m = 0,±1 causes this disagreement. The developed for this purpose experimental procedure can also be used as the basis for the new area of positron spectroscopy, connected with the investigation of the anisotropic (spin dependent) interaction of positronium in the media.