Hi Connie;
Welcome to TKL, you're gonna love it here. The friendliest, most helpful, most caring and compassionate people on the net post recipes and information on these boards.
Here's the recipe you are looking for, I found it on the Mortens Recipe Collection.
Ammonia Cookies

Ingredients (96 servings)
1/2 c Shortening
1 1/2 c Sugar
1 Egg
5 1/2 c Pastry flour
3/4 ts Salt
1 c Milk
1 1/2 ts Oil of lemon*
2 ts Ammonium carbonate*

Instructions
Directions: * may be purchased in a drug store. Cream shortening and add sugar. Add egg and oil of lemon. Mix. Sift flour before measuring. Measure flour and sift with salt. Dissolve ammonium carbonatein a little of the milk. Add flour and liquid alternately mixing after each addition. Chill dough. Roll 1/4" thick. Cut in squares. Place on greased baking sheet. Sprinkle cookies lightly with sugar. Bake 12-15 mins. in a 375 oven. Yields 8 doz. 2"squares. This recipe was adapted from a Five Roses Cookbook, ca. 1925. for inclusion in booklet to celebrate Canada's centennial in 1967. The booklet was called Centennial Kitchen Cookies.