Chill cream thoroughly.
Meanwhile soften gelatin in cold water for 5 minutes.
Heat pineapple juice to simmering, add gelatin and stir until dissolved.
Add salt and cool.
Then add lemon juice and pineapple.
Chill until thick.
Remove cream to a cold bowl and beat until stiff.
Fold lightly but thoroughly into pineapple mixture.
Turn into chilled refrigerator tray, set refrigerator at coldest temperature and freeze for several hours in freezing compartment until firm.
Return controls to normal refrigerator temperature and ripen until ready to serve.