Wash and cut the rhubarb in sticks.
Pour 1 litre of water in a pan and bring to a boil over high heat.
Then immerse the rhubarb sticks in the boiling water and cook over medium heat until softened.
Pour into a nylon sieve, in order to collect the juice (use a nylon sieve rather than a metal one, since the metal one may give a bitter taste to acid foods).
Add the sugar to the rhubarb juice and mix well until sugar is dissolved.
Add the sugar, the other fruit juices and salt to the rhubarb juice.
Put the juice in the freezer until cooled.
Just before serving, put ice cubes in the glasses. Fill with equal parts of rhubarb juice and ginger ale (or carbonated water).
Serve very cold.
Yield: about 8 cups.