There are many advertisements in the cookbook that encourage the reader to buy ammonia (like the one on the bottom of page 12). Ammonia is a potentially deadly and corrosive chemical commonly found in fertilizer, plastic manufacturing, pesticides, and cleaning solutions. So, you may be thinking…why would this cookbook require one to use a harmful chemical in a cookie recipe?! In reality, the ammonia that was used for cooking was baker’s ammonia (or ammonium bicarbonate), which was used in place of baking soda and baking powder before they were invented in the 19^th century (pictured above). Food-grade ammonia is completely safe to consume, can be used interchangeably with baking powder or baking soda, and can produce a more desirable taste and texture in baked goods, like the Ammonia Cookies pictured here.