"Spirits of Hartshorn" is an old term that refers to ammonia solution, a colorless gas with a pungent odor. Other synonyms for this chemical compound include aqua ammonia, ammoniacal liquor, and ammonia water. This liquid solution is commonly used as a cleaning agent, industrial refrigerant, and source of nitrogen in fertilizers. Additionally, it has applications in the medical and pharmaceutical industries as a bronchodilator and disinfectant. Its strong alkaline properties make it an effective ingredient in several household cleaning products, including oven cleaners, floor polishes, and window cleaners. While ammonia solution is known for its caustic qualities, it remains a versatile chemical compound in modern-day manufacturing and everyday household use.