A study was made of the zeolite NaA containing different materials (water, ice, selenium) by using spectral methods for measuring the lifetimes of positrons and the angular distribution of annihilation photons. The data show that when the zeolite cavities are filled, positron states can be observed. However, in dehydrated NaA one does not observe signs indicating that the positron states have been formed when angular distribution of annihilation photons measurements are made in a magnetic field. It is shown that it is possible to use the annihilation characteristics of positronium to determine the intermolecular distances in clusters of additives which are dispersed in the zeolite NaA.