In a saucepan, bring apricots and water to a boil. Reduce heat; simmer, uncovered, for 10 minutes or until apricots are softened.
In a bowl, combine 2 cups sugar, cornstarch and salt; stir into apricot mixture. Bring to a boil. Reduce heat; cook and stir for 1 minute or until thickened.
Remove from the heat; stir a small amount of hot filling into yolks. Return all to pan, stirring constantly. Bring to a gentle boil; cook and stir 1 minute longer or until glossy and clear.
Remove from the heat; stir in butter. Keep warm.
In a bowl, beat egg whites and cream of tartar on medium speed until soft peaks form. Gradually beat in remaining sugar, 1 tablespoon at a time, on high until stiff glossy peaks form and sugar is dissolved.
Pour hot filling into crust.
Spread meringue evenly over filling, sealing edges to crust.
Bake at 325° for 25-30 minutes or until golden brown. Cool on a wire rack for 1 hour. Chill for at least 3 hours before serving. Refrigerate leftovers.