Key lime pie

2 envelopes Knox gelatin
1 cup sugar
1/4 tsp salt
6 egg yolks
3/4 cup lime juice
1/2 cup water
1 tsp grated lime peel
Green food color
6 egg whites
3/4 cup sugar
2 baked graham cracker shells
Whip cream and lime for garnishes

Mix gelatin, sugar and salt. Beat egg yolks, lime juices and water.  Pour into a saucepan. Add gelatin mixture and heat on medium heat until mixture boils, stir constantly.  Stir in lime peel and food coloring.  Pour into a bowl and refrigerate until mixture mounds when dropped from a spoon.  Don't leave in an aluminum pan.  Beat egg whites until soft peaks form.  Gradually add 3/4 cup sugar and continue beating until stiff, fold into lime  mixture. Pou into shells, serve with whip cream.