This is a recipe I have also usesd (more modern)

TOMATO BUTTER/Jam
Yeild: about 9 - 6 oz glasses

3 cups prepared tomatoes, (about 2 1/2 pounds)
1 1/2 teaspoons grated lemon rind
1/4 cup lemon juice (2 lemons)
6 1/2 cups sugar
1 bottle Certo Fruit Pectin

First prepare fruit. Scald peel and chop about 2 1/2 pounds fully ripe tomatoes. Bring to a boil and simmer 10 minutes.
Measure 3 cups into a "large" saucepan.
Add 1 1/2teaspoons grated lemon rind and 1/4 cup
lemon juice to the tomatoes.

To the measured fruit in a saucepan, add the exact
amount of sugar specified in the recipe. Mix well.
Place over high heat, bring to a full rolling boil, and boil hard for 1 minute, stirring constantly.
Remove from heat; at once stir in the Certo. Skim off foam with metal spoon. then stir and skim for 5 minutes to cool slightly, to prevent floating fruit.
Ladle into glasses.
Cover at once with 1/8 inch hot parafin.

Note:I no longer use parafin to seal jams and jellies, I
process them in a boiling water bath for 10 minutes.