alkali vs antacid

alkali

noun
  • One of a class of caustic bases, such as soda, soda ash, caustic soda, potash, ammonia, and lithia, whose distinguishing characteristics are dissolving in alcohol and water, uniting with oils and fats to form soap, neutralizing and forming salts with acids, turning to brown several vegetable yellows, and changing reddened litmus to blue. 

  • Soluble mineral matter, other than common salt, contained in soils of natural waters. 

antacid

noun
  • An agent that counteracts or neutralizes acidity, especially in the stomach. 

adj
  • Counteracting or neutralizing acidity, especially in the stomach. 

How often have the words alkali and antacid occurred in a corpus of books? (source: Google Ngram Viewer )