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Table of Contents
May 1997
Volume 74, Issue 5
Pages 473-607
About the Cover:
A small portion of the crystal lattice of zeolite A is shown superimposed on a sample of laundry detergent (see page 569). The red spheres represent oxygen atoms and the gray spheres represent either silicon or aluminum atoms. When zeolite A is manufactured, the ratio of aluminum to silicon can be varied. For each aluminum there is a corresponding Na+ ion somewhere in one of the open channels visible on the cover. Exchange of these sodium ions for calcium or other ions is responsible for the water-softening ability of zeolite A and hence for its presence in laundry detergents.
