The Collaborative International Dictionary of English v.0.48:

Thalline \Thal"line\, n. [Gr. ? a young shoot or branch.]
   (Chem.)
   An artificial alkaloid of the quinoline series, obtained as a
   white crystalline substance, C10H13NO, whose salts are
   valuable as antipyretics; -- so called from the green color
   produced in its solution by certain oxidizing agents.
   [1913 Webster]