alkali vs seawater

alkali

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

  • 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. 

seawater

noun
  • The saltwater of a sea or ocean. 

adj
  • Associated in some way with seawater, or intended for dealing with seawater. 

  • Consisting of seawater. 

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