Old-Fashioned Popcorn Balls - Recipe from 1932

How to make Old-Fashioned Popcorn Balls. Recipe is from the Household Searchlight Cookbook era 1932 - out of my Grandmother's cookbook. Wow 82 year old recipe!
RECIPE:
1/2 Pound popcorn - (measurement before popping is 1/2 pound) - Pop the popcorn
2/3 cup Light Corn Syrup
2 cups sugar
2/3 cup boiling water
2 teaspoons cream of tartar
2 tablespoons vinegar
2 tablespoons melted butter
2 teaspoons vanilla extract
1/8 teaspoon baking SODA
one CANDY THERMOMETER

Pop the corn - put into very large kettles or bowls. Combine syrup, sugar, water and the vinegar in large saucepan. Heat to boiling. Add the cream of tartar. Boil to Soft Crack stage (275-280 degrees) I did it till 275. Remove from burner. Add butter, baking soda and vanilla. Stir and pour quickly over the popped corn. Stir with wooden spoon or rubber spatula that is heat resistant. Butter your hands. Lightly touch the popcorn and when it is cool enough but still hot (if that makes sense) start forming into balls and place onto wax paper or parchment paper. When cool, wrap in plastic wrap or wax paper twisting the ends - store in large rubbermaid or tin container. Makes about 27 medium to large popcorn balls. Very very delicious!
IF YOU DON'T HAVE THERMOMETER do the following:
have a 1/2 cup of cold water handy and a teaspoon
when you think you are getting close to the right temp- start checking the candy part by taking a 1/2 teaspoon of the candy and drop it into cold water-
in the test for Soft Crack Stage the candy should form brittle threads in the water, the spiral softens when you remove it from the water. If they remain brittle you have gone too far, so keep testing early in the stages.