Here’s a recipe slip for homemade tomato jam, giving two different recipes (one for ripe tomatoes and the other for green tomatoes). Recipe is written as-is below along with a scanned copy (front side only).
Tomato Jam
Boil 2 c. peeled chopped ripe tomatoes with 2 c. sugar for 10 min.
Add one thinly sliced lemon & one 3 oz. box of lemon gelatin & boil for 10 min. more.
Put in clean hot jars & seal.
or,
Add 4 c. sugar to 5 cups chopped or ground green tomatoes. Boil hard for 7 min. then add two 3 oz. packages of raspberry or strawberry gelatin & pour into jars.
Before using this recipe, it’s important to read this page [1], the “Safe Canning & Food Preservation” section.