Oh, I have that book! Just got it from the Library. Let me look it up for you.
The book I have is called:
The Little House Cookbook
Frontier Foods from Laura Ingalls Wilder's Classic Stories
By Barbara M. Walker
Let's see...
Apple Core Vinegar. It's actually a long paragraph, so I'll type it out for you.
"Start you vinegar making as soon as the season's new apple crop is available so you can make several tries if necessary.
For 1/2 gallon of cider vinegar you will need:
Spring, rain, or well water, 1/2 gallon
Honey, 2 cups
Peels and cores of 12 or more apples
Dry yeast, 1/2 package (1 1/2 tsps optional)
Cider vinegar, 1/2 cup commercial, for comparison only
Small barrel or plastic gallon jug; cork or lid; sipping straws
A fine stand-in for a barrel is a gallon plastic milk jug--the kind with a square base, self-handle, and narrow neck. It must be washed well and scalded. Find a place in the warm kitchen where it can rest on a side, with the narrow opening serving as a bunghole. Cut an opening on the top surface to receive a wide cork or plastic lid, the closing should not be airtight.
Boil the water, pour it in the jug, and stir in honey, peels, and cores. Cover, set aside, and check daily for bubbling. If none occurs in a week, add the yeast. If mold forms on the surface, skim it off without disturbing the contents.
After a month the bubbling will have stopped and souring begun. Now it is up to your taste to tell you when the vinegar is ready to use. To take a sample from the jug, plunge in a sipping straw, close the end with your thumb, and remove the straw half-full. Judge the strength by comparing with a taste of commercial vinegar.
In two months the vinegar may be sour enough to use in cooking and salad dressings, Try to decant a quantity from the bung without shaking up the conents. Replenish the barrel with any fermented matter on hand.
At some point a milky film may form on or below the surface of the vinegar in the barrel. This is a mother, a welcome sign of acetic acid bacteria but a possible nuisance. Best remove it, along with the other solid matter in the barrel.
Use your homemade product wherever vinegar is called for in this book except in pickling, which requires a vinegar of proven acidity. Recommended uses are on Fried Fish, with sugar on lettuce leaves, in Green Pumpkin Pie in Ginger Water and in Vinegar Pie."
Ok, that's it.