Guilt-free Partait

3 small boxes sugar free gelatin, lemon, lime, and raspberry
3 cups boiling water
1 cup ginger ale
1 cup 7-up
1 cup soda water

enough glasses to hold 6 cups and look nice.
Use very cold soda. Cans hold more fizz.
Cool one layer until firm before adding next layer.
Let each batch of gelatin cool before adding the
carbonated beverage. Stir only a little to preserve fizz.
Cool holds fizz better than warm, and we don't want to 
redissolve the lower layer.
Add berries or fruit to serve.
From "Cream Puff Murder" a Hannah Swensen mystery by Joanne Fluke.