Correct spelling for the English word "theolin" is [θiːəlˈɪn], [θiːəlˈɪn], [θ_iː__ə_l_ˈɪ_n] (IPA phonetic alphabet).
Heptane, C7H16, a colorless liquid hydrocarbon resembling benzene, obtained from petroleum.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.