chalybeate vs ferrous

chalybeate

adj
  • Containing dissolved salts of iron. 

  • Tasting of iron, said of mineral water. 

noun
  • A mineral water containing iron, a voguish general remedy during the 17th-19th century. 

ferrous

adj
  • Of or containing iron. 

  • Of compounds of iron in which it has a valence or oxidation number of 2. 

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