Combine chicken, water, onion, celery tops, salt, and peppercorns in a kettle; cover.
Simmer 1 hour, or until chicken is very tender; remove from broth.
Strain broth into a 2-cup measure.
Soften gelatin in apple juice in a medium-size saucepan; stir in 1 1/2 cups of the broth.
(Chill any remaining broth to add to soup for another meal.)
Heat gelatin mixture slowly, stirring constantly, until gelatin dissolves; remove from heat.
Cool for later stage.
Pull skin from chicken and take meat from bones; dice fine.
(There should be about 2 cups.)
Blend mayonnaise or salad dressing into gelatin mixture in saucepan; pour into an ice-cube tray.
Freeze 20 minutes, or until firm about 1 inch in from edges.
Spoon into a chilled large bowl; beat until fluffy thick.
Fold in diced chicken, celery, almonds, and olives.
Spoon into 3 individual molds.
Chill several hours or until firm.
Salad can be eaten from the mold, or unmolded onto a lettuce-lined plate and garnished with melon crescents.